text:
Hotline Miami Developers Deny Hotline Miami 3 Rumors
Despite what a recent video suggests, Hotline Miami 3 isn't in development.
By Matthew Byrd | August 5, 2019 |
A cryptic video released via Twitter has gotten gamers buzzing about Hotline Miami 3. However, Devolver Digital has stepped in to confirm that they are not actually developing a sequel to the revolutionary indie title.
"This is a very cool fan film (or teaser for one maybe) but rest assured there is not another Hotline Miami game in development," reads a tweet from the Hotline Miami Twitter account. Devolver Digital also reached out to IGN to confirm a new Hotline Miami game is not in development.
Interestingly, the tweet from the Hotline Miami account also seems to suggest that they have no idea what the mysterious video is related to. Like many at this time, they are speculating that it's related to some kind of fan film or similar project. The fact that they seem to be in the dark about the specifics would rule out the possibility that the video is a teaser for some kind of official Hotline Miami adaptation.
More importantly, though, it confirms that this video is not only not related to a Hotline Miami sequel in development but that the Hotline Miami team isn't working on a sequel to the series at the moment whether it's related to the video or not.
Further Reading: 30 Best PC Games to Play in 2019
That's unfortunate. Hotline Miami is one of the greatest action games ever made and one of the most important indie titles of the indie game era. While Hotline Miami 2 didn't quite recapture the magic of the original experience, it still featured the original's puzzle-like action sequences and wonderfully over-the-top '80s aesthetics.
As for that fan video, we'll certainly have to keep an eye on whatever that's about as the initial teaser suggests it may be a fascinating project in its own right.
Matthew Byrd is a staff writer for Den of Geek. He spends most of his days trying to pitch deep-dive analytical pieces about Killer Klowns From Outer Space to an increasingly perturbed series of editors. You can read more of his work here or find him on Twitter at @SilverTuna014.
Read and download the Den of Geek SDCC 2019 Special Edition Magazine right here!
Tags: Devolver Digital
Matthew Byrd	| @SilverTuna014
Matthew Byrd is a freelance writer and entertainment enthusiast living in Brooklyn. When he's not exploring the culture of video games, he's wishing he had a…
Read more from Matthew Byrd
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redpajama_set_name: RedPajamaCommonCrawl


Although not as nice to look at as wooden posts, with a life expectancy exceeding 25 years, concrete fencing materials are a viable alternative to traditional wooden materials. We stock a range of concrete posts, gravel boards, repair spurs and decking support posts.
Concrete posts are normally dug into the ground and the post secured with either a drymix ballast and cement (about 7 to 1 mix with no extra water added) rammed up around the post or postmix ( follow directions on the bag). The amount of each that will be required will depend on the size and depth of the hole. Try to keep the hole diameter fairly tight around the post, 200 to 250mm (8″ to 10″) is good. Generally, for any fence height, the hole should be a minimum of 600mm (2′) deep. For fence heights over 1.5m we recommend that the hole depth is increased to a minimum of 750mm (2′ 6″).
Important: Check the depth of the hole carefully before dropping the post into the hole. Concrete posts are very difficult to lift back out of the hole if the depth is not correct.
Concrete posts are heavy so please lift with care and most sizes of concrete posts will require a minimum of 2 people to safely lift.
If the weight or lifting may be a problem you may wish to consider the much lighter metal DuraPost's as an alternative option.
For more information on any concrete products or to obtain a quote for your job please contact us or phone sales on 01892 864646.
Long lasting and easy to use with fence panels. Panels can be lifted out & replaced easily if required.
Panel security brackets can be fitted to stop panels being lifted out.
Four way weathered (Pyramid) post tops.
If the fence line is on a slope, you need to allow longer posts so that the panels can step down the slope.
Concrete Gravel boards are easy to use with slotted posts and fence panels as they keep the panel off of the ground and reduce the risk of the panel bottom rotting prematurely.
Cannot be used with post anchors.
Suitable for use with or without, concrete or wooden Gravel boards.
Posts are holed to allow wooden plates to be bolted on for gate hanging.
Concrete Spurs can be used to repair & extend the life of wooden fence posts that have rotted off at ground level.
They are concreted in down the side of the existing (or new) post and attached to the post above the break using either m10 coach screws or bolts.
Concrete spurs can be fitted to new wooden posts as part of the initial installation.
For attaching 2.885m Concrete Gravel Boards to Concrete Morticed Posts.
Can also be used to attach wooden gravel boards to concrete posts.


It's weekend catch-up time on the Green Blog, and yes, it did get dirty over the last few days. On Saturday I wandered, blinking, into the sunlight of my back-yard to see what I might be able to cultivate for myself.
I was pleased to find that I didn't have to take advantage of the www.wasteawarescotland.org.uk £8 compost bin scheme as some helpful neighbour had already got one installed. I plundered the spoils behind the little flap at the bottom to set up a growing spot of my own between what I would describe as a large spiky plant and a stout, boring little green shrub. Yes that's right, I am not a gardener.
Recognising this, and presumably worried about the safety of tall and spiky and short and boring, an elderly neighbour rushed out to make some enquiries about what I was planting. The answer was courgettes. A rather nice BBC video had explained the sowing process to me (available at www.bbc.co.uk/gardening/digin), but being far to busy to wait for something to germinate I just nicked a few from my green-fingered friend who had been tending to hers on a warm window sill for a few weeks.
My earnest neighbour, who seemed to know a lot about what I was doing wrong, advised that I both leave off planting my delicate seedlings until late May, when things had got a bit warmer, and planted them further apart – about 3 feet, rather than the tight formation I had been attempting.
In the end only one seedling stayed in the ground, mostly as an experiment to see if it could get a head-start because of the warm weather. Then I took the others back to my windowsill. Their time will come.


The increasing global attention to the threat of antibiotic resistance has spurred research and development of antimicrobial alternatives. Once such alternative is bacteriophages. Bacteriophages are viruses that infect and kill bacteria. There are thousands of different types and they are so abundant in the environment – an estimated 1030 live on the planet – that "we eat thousands of phages a day," says Manan Sharma, a research microbiologist with USDA's Agricultural Research Service. After they were discovered in 1915, scientists tried to use them to treat diseases like cholera. But the discovery of powerful antibiotics caused phage therapy to be essentially abandoned. That interest has returned in the 21st century as antibiotic resistance increases. But it's important to remember that bacteriophages are not infallible either. Similar to bacteria developing antibiotic resistance, "the target [of a phage] can change and most likely will change because it's a contestant evolutionary battle," Sharma says. Each bacteriophage is antagonistic toward specific bacteria or serotypes. Biotech companies have been working to isolate individual phages and define their hosts. "You have phages that are specific for E. coli or Listeria or Salmonella," Sharma says. "For example, you'll have a phage that's specific for E. coli O157:H7 that may not be specific for E. coli O26." So companies that commercially produce bacteriophages try to find phages that attack a broad set of hosts or create cocktails of phages with narrow targets. Sharma's lab has studied the effectiveness of some of these commercially-produced bacteriophages on cucumbers and lettuce inculcated with E. coli or Salmonella and found as much as a 2-log reduction. A 5-log reduction, or a 100,000-fold reduction, in bacterial counts is the goal for food safety interventions, but Sharma says even though bacteriophages may not be able to eliminate the target pathogen population, hopefully you're able to reduce it before subsequent treatments or so that storage conditions will not allow the bacteria to grow. Isolating the right bacteriophages takes a lot of work, but so does figuring out the best application of them. Is the best chance of reducing the bacterial population in the field, during packaging, in the wash water, or during another step in the production chain? "We found in our work that a direct spray application has given us the best results," Sharma says. "Incorporating them into wash water with lettuce hasn't really yielded the results that we would have liked to have seen." Each commodity's individual risks and production cycle could call for a different application. The consensus among microbiologists is that bacteriophages don't harm humans, but Sharma wonders how the general public would react to them if they become a widely used food safety intervention. Phages are essentially "natural" since they come straight from the environment, but plenty of people could view them as "injecting viruses into food." "I don't know if consumers would want that," Sharma says. "I'm not scared of consuming bacteriophages because I probably just did with the turkey sandwich I had for lunch." Bacteriophages are not the ultimate solution to solving the antibiotic resistance crisis, but they could be an important piece of the puzzle. After decades at the wayside, phages are "something old that has become new again," Sharma says, and they could probably benefit from more research and development.


text:
The death penalty doesn't work because good and evil are inevitably entangled [Opinion]
Opinion // Outlook
By Elizabeth Bruenig, The Washington Post Aug. 6, 2018
The death penalty doesn't work because good and evil are...
1of3The Vatican announced that Pope Francis has revised the catechism to hold that the death penalty is "inadmissible" in all cases, and that the church must advocate "for its abolition worldwide."
2of3Protestors against the death penalty react to the clemency of inmate Bart Whitaker outside the Huntsville Unit Thursday, Feb. 22, 2018 in Huntsville. Bart Whitaker was scheduled for execution on Thursday and was granted clemency by the governor of Texas. He was sentenced to death in the murders of his mother, Patricia Whitaker, and his 19-year-old brother, Kevin Whitaker, on December 10, 2003, in Sugar Land.Photo: Houston Chronicle
3of3Gloria Rubac with the Texas Death Penalty Abolition Movement stands in front of the Huntsville Unit to protest the execution of Christopher Anthony Young Tuesday, July 17, 2018, in Huntsville. Christopher Anthony Young is scheduled to be executed for the 2004 murder of Hasmukh Patel, an owner of a San Antonio convenience store, who was gunned down during a robbery.Photo: Melissa Phillip, Houston Chronicle
On Thursday, the Vatican announced that Pope Francis has revised the catechism to hold that the death penalty is "inadmissible" in all cases, and that the church must advocate "for its abolition worldwide." The change comes amid news of the resignation of former cardinal Theodore McCarrick, who has been accused of abusing men and boys during his decades of service. There may never have been a more poignant time for an announcement like this: With a disgraceful abuse tempting many to leave the church, the Vatican's clarity on capital punishment offers a well-timed reminder of what is pure and holy in the Christian tradition. In the church, earthly institution that it is, good and evil are inevitably entangled.
EDITORIAL: Death penalty inappropriate for a convicted murderer who ate his own eye
The church had previously made clear its general opposition to the death penalty. Vatican statements framed the latest shift more as a clarification reflecting evolution in papal thought than a change in teaching. In its letter to bishops, the Congregation for the Doctrine of the Faith noted that Francis' decision followed logically from developments introduced by his two predecessors, Benedict XVI and John Paul II. Both popes had emphasized the affront the death penalty represents to human dignity, and had called for its abolition, but stopped short of formalizing their entreaties in doctrine.
Prior to this clarification, the catechism allowed for the death penalty only within narrow parameters. "Assuming that the guilty party's identity and responsibility have been fully determined," it read, "the traditional teaching of the Church does not exclude recourse to the death penalty if this is the only possible way of effectively defending human lives against the unjust aggressor." Determining identity is difficult enough; assessing responsibility is even harder, implying not only criminal fault but also full moral culpability. And having the state take a life is rarely the only way of defending innocents from the predation of a known assailant.
OPINION: The Catholic Church has obliterated its ability to inspire trust
At different times, under different circumstances, the church's tolerance of executions has been more enthusiastic. But the church inclines to life. Even in periods traditionally imagined as its bloodiest - the Dark Ages, that (arguably unfairly) maligned era between the end of antiquity and the Renaissance - it was the church that brought about sanctuaries, both in the literal sense and in the figurative that followed from it. Criminals condemned to be executed could take shelter inside church properties; sometimes, clergy would negotiate their release on the condition that they be allowed to live, often in exile.
Maybe that seemed unsatisfying, then. It would very likely seem unfair now, in an era with little tolerance for mercy in public policy. A colder justice can be attractive. I can understand - especially having been raised in conservative Texas - why someone might support the death penalty. It isn't solely the province of the simplistic or the cruel. Hannah Arendt's imagined speech to the condemned Adolf Eichmann in her book "Eichmann in Jerusalem" offers a moving rationale: "Just as you supported and carried out a policy of not wanting to share the earth with the Jewish people and the people of a number of other nations . . . no member of the human race, can be expected to want to share the earth with you. This is the reason, and the only reason, you must hang." Hang Eichmann did.
OPINION: A rush to death risks executing the innocent
Arendt, herself an excellent chronicler of popes and saints, believed in good and evil, and knew the one from the other. It's impossible not to sympathize with her desire to live in a world at least somewhat cleansed of evil. I imagine the same motives, along with some less noble, motivate most who advocate for the death penalty. But killing to rid the world of evil is an empty errand. It doesn't work, in the end.
In the world we encounter evil. Our impulse is to destroy it. But here in the world, good and evil are hopelessly entwined; you contain evil, bring it to account, heal injuries and make restitution for wrongs - but it is impossible to finally destroy all evil without also taking the good with it. This is because good and evil are tangled in the hearts of human beings and cannot be sorted out in this life. And since the goodness in us - the humanity - is worth preserving, we ought not inflict death as a punishment, but rather cling to life, even unto the very last moment of hope.
Bruenig is an opinion columnist at The Washington Post.
What's your take?
Submit a letter to the editor here.
Thursday letters: Calling out No. 45
Renewable energy can't keep Texans' A/C humming [Opinion]
Slamming door on asylum seekers is illegal, immoral [Editorial]
Navarrette: The Squad shakes up the Washington establishment — on both...
'Underage women': The oxymoron that hides Jeffrey Epstein's crime...
Trump's war on HIV is real but money alone can't kill it [Editorial]
Carrasco: Set phasers to becoming more environmentally conscious
Wednesday letters: Winning hearts, minds of Houston ISD students


text:
Q: Zip files contain same files but have different hashes? I have created hundreds of folders and text files using php, I then add them to a zip archive.
This all works fine but if I create another zip archive using the same folders and files, the new archive will have a different hash to the first one. This is the same if I use winrar instead of php to create an archive.
It only seems to show different hashes when I zip the files I have created through php, yet they open fine.
Very strange anyone shed any light on this?
Thanks

A: There is certainly some difference in the files. If the lengths are not exactly the same, the hash will be different. You can use a comparing hex editor, like Hex Workshop for example, to see what exactly the differences are.
Possibilities that come to my mind:

*

*As @orn mentioned, there may be a timestamp in the zip format you are using (not sure).

*The order that the files are added to the archive may be different (depending on how you're selecting them / building the source array).

A: Zip is not deterministic. To solve this zip problem (it's really problem when you have CI and need to update AWS lambda, for example and don't want to update it each time, but only when something was really changed) I used this article: https://medium.com/@pat_wilson/building-deterministic-zip-files-with-built-in-commands-741275116a19
Like this:
find . -exec touch -t "$(git ls-files -z . | \
  xargs -0 -n1 -I{} -- git log -1 --date=format:"%Y%m%d%H%M" --format="%ad" '{}' | \
  sort -r | head -n 1)" '{}' +
zip -rq -D -X -9 -A --compression-method deflate dest.zip sources...

A: You can consider using deterministic_zip it solves this issue, from its documentation:

There are three tricks to building a deterministic zip:

Files must be added to the zip in the same order. Directory iteration order may vary across machines, resulting in different zips. deterministic_zip sorts all files before adding them to the zip archive.
Files in the zip must have consistent timestamps. If I share a directory to another machine, the timestamps of individual files may differ, despite having identical content. To achieve timestamp consistency, deterministic_zip sets the timestamp of all added files to 2019-01-01 00:00:00.

Files in the zip must have consistent permissions. File permissions look like -rw-r--r-- for a file that is readable by all users, and only writable by the user who owns the file. Similarly executable files might have permissions that look like: -rwxr-xr-x or -rwx------. deterministic_zip sets the permission of all files added to the archive to either -r--r--r--, or -r-xr-xr-x. The latter is only used when the user running deterministic_zip has execute access on the file.

Note: deterministic_zip does not modify nor update timestamps of any files it adds to archives. The techniques used above apply only to the copies of files within archives deterministic_zip creates.

redpajama_set_name: RedPajamaStackExchange


text:
\section{Introduction}

Cavity quantum electrodynamics (CQED) is an outstanding platform to study non-linear atom-field dynamics and phase transitions in driven-dissipative systems \cite{ritsch_cold_2013,tanji-suzuki_interaction_2011,mivehvar_cavity_2021}. In its natural setting, a CQED system is driven by external coherent sources, e.g. by laser or microwave radiation, meanwhile the energy is dissipated through a number of channels leading to a steady state resulting from a dynamical equilibrium between driving and loss \cite{walls_inputoutput_2008}. One dissipation channel is the coupling of the cavity field to external, freely propagating, spatially well defined modes, which can be efficiently collected for detection. The outcoupled field then affords an indirect observable of the intracavity steady state \cite{wiseman_quantum_2009}, in the sense of continuous weak quantum measurement.

Cavity QED schemes typically involve few degrees of freedom that are relevant to the atom-light interaction. The field is composed of only a single or a few modes, and the interacting atoms can be represented by a few electronic states. The spatial dimension in which the geometrical size of the atomic cloud can grow macroscopic is irrelevant as only the position relative to the cavity mode antinodes matters. Although the intracavity system size is small, in this sense, the continuous measurement of the outcoupled field is a macroscopic observable and so, it is an order parameter of the system. Transitions between steady states can be affected by changing drive parameters and monitored as a macroscopic change in the recorded signal. Such driven-dissipative phase transitions have been discussed and experimentally studied recently in CQED  \cite{nagy_dicke-model_2010,baumann_dicke_2010,arnold_self-organization_2012,schmidt_dynamical_2014,klinder_dynamical_2015,leonard_supersolid_2017,kollar_supermode-density-wave-polariton_2017,fink_signatures_2018}.

In this paper we present a type of first-order phase transition \cite{vukics_finite_2019,brookes_critical_2021,curtis_critical_2021,reiter_cooperative_2020,megyeri_directional_2018,hannukainen_dissipation_2018,rodriguez_probing_2017,casteels_critical_2017} of an ensemble of cold atoms in an optical Fabry-P\'erot cavity \cite{lambrecht_cold_1995,elsasser_optical_2004,culver_collective_2016,kawasaki_geometrically_2019}. Such a physical realizations of CQED systems have a multitude of applications: the cavity can enable sensitive measurement of the atomic dynamics or state at spectroscopic sensitivity below the standard quantum limit for coherent spin states \cite{chen_cavity-aided_2014,zhang_collective_2012},  real-time monitoring of the spatial distribution \cite{niederriter_cavity_2020} or the atom number in evaporative cooling of atoms \cite{zeiher_tracking_2021}. Superradiance decoherence caused by long-range Rydberg-atom pair interactions, too, has been demonstrated by using cavity-assisted measurements \cite{suarez_superradiance_2022}. Another prospect of strongly coupled atom-cavity  systems is given by optical lattice clocks which are based on lasing on a narrow atomic transition within a resonator \cite{muniz_cavity-qed_2021, vallet_noise-immune_2017, hobson_cavity-enhanced_2019, schaffer_lasing_2020}. Finally, the cavity mode can have a dynamical role such that the hybrid atom-photon excitations introduce new features to non-linear optics. For example, in the case of multiple laser drives, the suppression of polariton excitation by quantum interference \cite{yang_interference_2014} and the proof-of-principle of a multiplexed quantum memory based on spin-waves \cite{cox_spin-wave_2019} have been demonstrated. In these systems, cold atoms can be held in a magneto-optical trap (MOT), or loaded into a cavity-sustained optical dipole trap, or be tightly confined in atom-chip based magnetic traps \cite{kohler_negative-mass_2018}. In our experiment, we use atoms in a large magnetic trap \cite{dombi_self-trapping_2021}, and the cavity mode plays both a diagnostic and dynamical role in the observed phase transition.

In the present study, the phase transition involves two control parameters provided by tunable laser drive powers. One of the lasers is used to probe the transmission of the resonator, whose driven mode is coupled to an atomic transition, whereas the other laser effectively repumps the atoms back into the two-dimensional atomic subspace that is coupled to the cavity. With infinitely strong repumper, the well-known scenario of the atomic-saturation-induced optical bistability in an effectively two-level system is recovered \cite{Martini1993Optical,lambrecht_optical_1995,Sauer2004Cavity,sawant_optical-bistability-enabled_2016}.  Decreasing this control parameter, the system still exhibits bistability with the cavity drive strength control parameter, however, the role of saturation is taken over by populating another hyperfine ground state. Ultimately, the bistability develops into the co-existence of two \emph{phases} in which the internal electronic state of the atoms in the laser-cooled cloud is a pure state, namely, one or the other of the two hyperfine ground states. Recently, in this zero repumper limit, the temporal dynamics of the collapse of an unstable phase has been observed \cite{clark_time-resolved_2021}. In this paper we go on to explore the full phase space spanned by the two control parameters and reveal experimental signatures of the phases and the transition between them.

The paper is structured as follows. In Sec.~\ref{sec:two-way}, we present a model system of competing dynamical optical pumping processes to establish a framework in which to describe our experiments. In Sec.~\ref{sec:PhaseDiagram}, the phase diagram is mapped out by solving the mean-field equations of the model and new features of the bistability domain are pointed out. We make a clear distinction with respect to the well-known case of absorptive optical bistability. In Sec.~\ref{sec:experiment}, the experimental scheme is described and the correspondence to the theoretical model is established. Sec.~\ref{sec:dynamical} is devoted to measurements on the long-time behaviour of the system and to the dynamical signatures of the bistability. Both dynamical oscillations and enhanced fluctuations of the order parameter are demonstrated. In Sec.~\ref{sec:hysteresis} we show that adiabatic ramp cycles of the control parameters lead to hysteresis, which is clear evidence of a first-order phase transition in the system \cite{rodriguez_probing_2017}. Finally, we conclude in Sec.~\ref{sec:conclusion}.

\section{Model of two-way optical pumping of atoms in the cavity}
\label{sec:two-way}

We consider ${N}$ atoms interacting with a single mode of a linear optical resonator, as represented schematically in Figure~\ref{fig:scheme}. The cavity mode is driven by a laser with effective amplitude, $\eta$, and angular frequency, $\omega$. This latter is close to the mode resonance, $\omega_C$, such that the detuning $\Delta_C\equiv \omega-\omega_C \lesssim \kappa$, where $\kappa$ is the mode linewidth (HWHM). The cavity field couples to the electric dipole transition $|g\rangle \leftrightarrow | e \rangle$, with coupling constant $g$ (single-photon Rabi frequency). The excited atomic state, $| e \rangle$, decays mostly to $| g \rangle $ with rate $\gamma$ (HWHM), however, a weak decay channel exists to another state, $| f \rangle $, with rate $\Gamma\ll\gamma$. There is a repumper laser illuminating the atoms from the side which performs optical pumping on the atoms back to the state  $| g \rangle $ at a rate $\lambda$. The atomic detuning, $\Delta_A$, is large so the $\Lambda$-atom scheme does not result in electromagnetically induced transparency \cite{joshi_controlling_2003}.

\begin{figure}
\includegraphics[width=\linewidth]{scheme_complete}
\caption{(a) The configuration of our CQED scheme. Cold atoms are loaded into a linear cavity and kept in a magnetic quadrupole trap. The cavity is driven with variable effective amplitude, $\eta$, through an incoupling mirror and the transmitted light detected with an avalanche photodiode. The atoms are illuminated from the side by a repump laser of variable power, characterized by the pumping rate, $\lambda$. (b) The relevant part of the atomic level scheme. The transition from the ground state, $|g\rangle$, to the excited state, $|e\rangle$, couples to the cavity mode, resulting in an effective drive amplitude, $g\,\alpha$, where $\alpha$ is the field mode amplitude. The transversely injected repump laser drives the transition from $|f\rangle$ to $|g\rangle$ via other excited states (not indicated). Panels show the cavity transmission accompanying the optical pumping into the states $|f\rangle$ and $|g\rangle$. (c) Atoms in state $|g\rangle$ detune the cavity mode resonance with respect to the laser frequency set on resonance with the empty cavity.
}
\label{fig:scheme}
\end{figure}

The steady-state of this system manifests a non-trivial phase diagram as a function of the control parameters $\eta$ and $\lambda$. Bistability originates from the competition of the two optical pumping processes, where one of them involves a non-linear cavity-assisted population transfer. A single atom in state $| g \rangle $ detunes the cavity mode resonance by an amount $\delta$. For large-enough atom number, the collective dispersive shift of the atom cloud, $N\,\delta$, can push the mode out of resonance, $|\Delta_C - N\delta| \gg \kappa$, so that the drive $\eta$ is ineffective in exciting the cavity mode. As there is no field in the cavity, the atoms are not excited from the state $| g \rangle $. This solution, dubbed "transmission blockade", is a steady state. However, it becomes unstable for very large drive strength $\eta$. The Lorentzian cutoff does not eliminate perfectly the transmission. The blockade may break down in a runaway process: for increased cavity drive amplitude, the tiny amount of light infiltrating the cavity excites atoms to $| e\rangle $, which, in turn, results in a reduction of the collective resonance shift and in even more light entering the cavity. This positive feedback amounts to a run-away optical pumping toward the state $|f\rangle$. The extent to which the atoms accumulate in state  $|f\rangle$ depends on the repump rate $\lambda$. For weak $\lambda$, they accumulate; for strong $\lambda$, the atoms are pumped back to $|g\rangle$ and restore the blockading regime. In between, there is a bistability domain where the two steady states can coexist in the form of a statistical mixture.

The competition between the two optical pumping processes can be described by a semiclassical mean-field model \cite{davidovich_sub-poissonian_1996}. The operator variables in the Heisenberg--Langevin equations are replaced by c-numbers. Let us use the cavity mode amplitude, $\alpha$, and the collective atomic polarization, $M=\sum_i |g_i\rangle\langle e_i |$, where the atoms are indexed by $i=1\ldots {N}$. The populations in the states $|g\rangle$, $|e\rangle$, and $|f\rangle$ are denoted by $N_g$, $N_e$, and $N_f$, respectively. The mean-field equations of motion read
\begin{equation}
\label{eq:meanfield}
\begin{split}
  \dot \alpha &=  (i \Delta_C-\kappa ) \alpha + gM + \eta\,,\\
 \dot M&= (i \Delta_A -\gamma -\Gamma ) M + g\left[N_e-N_g\right]\alpha\,, \\
  \dot N_e&= - g\left[\alpha^* M+ M^* \alpha\right]-
            2 (\gamma + \Gamma)  N_e\,,\\
  \dot N_g&=g\left[\alpha^* M+M^* \alpha \right]+
          2 \gamma N_e  + \lambda N_f \,,\\
  \dot N_f &=  2 \Gamma  N_e - \lambda N_f \,.
\end{split}
\end{equation}
The first equation describes the cavity mode as a driven oscillator which is coupled to the atomic polarization with the strength given by the single photon Rabi frequency, $g$. The second accounts for the atomic polarization due to the cavity field, this process includes saturation nonlinearity. This system of equations is written in a frame rotating with the cavity drive frequency, $\omega$, so the relevant atomic frequency is the detuning $\Delta_A = \omega - \omega_{ge}$, with $\omega_{ge}$ being the transition frequency between states $| g \rangle$ and $| e \rangle$. With these parameters, a single atom induces a cavity resonance shift $\delta=g^2\Delta_A/(\Delta_A^2 + \gamma^2)$, which can be approximated by $g^2/\Delta_A$ in the large atomic detuning regime ($|\Delta_A|\gg \gamma$). In the rest of this paper, we consider the case of resonant driving of the empty cavity, $\Delta_C=0$. Finally, the last three equations represent the evolution of the populations. Besides the cavity-atom interaction and the spontaneous emission term with $\gamma$, here the decay from state $|e\rangle$ to $| f \rangle$ at a rate $\Gamma$ and the repumping of the state $|g\rangle$ from $| f \rangle$ at a rate $\lambda$ are included. This model is a mean-field approach replacing the effect of the individual atoms at different positions and moving with different velocities by collective variables referring only to the internal degrees of freedom.

Although the model is heavily simplified, it is sufficient to capture the main features of the steady-state phase diagram. In particular, the reason why we consider the repumper acting only on the populations of states $\ket g$ and $\ket f$, without creating polarization between them will be explained in Sec. \ref{sec:experiment}.

\section{Steady-state phase diagram}
\label{sec:PhaseDiagram}

The driven-dissipative system defined by Eqs.~(\ref{eq:meanfield}) evolves
towards a steady state that can be calculated by setting the temporal derivatives to zero, and solving the inhomogeneous nonlinear system of equations. Fig.~\ref{fig:PhaseDiagram} presents a color map of the cavity
transmittance in the steady state as a function of the two drive strengths, cavity drive amplitude $\eta$ and repump rate $\lambda$. The transmittance is the transmitted intensity normalized to that of the empty resonator with exactly the same drive $\eta, \omega$. One can clearly observe the blockaded regime for small $\eta$, where the cavity field mode is not populated (dark blue region) as well as a `bright' phase with high transmission (yellow region). These phases are separated by a bistable domain (white stripe), where the system has two stable steady states. These solutions are plotted in Fig.~\ref{fig:bistabcuts} for cross sections of fixed $\eta$ and $\lambda$ values, indicated by dotted and dashed lines in Fig.~\ref{fig:PhaseDiagram}, respectively.

\begin{figure}
\includegraphics[width=0.99\linewidth]{phase_diagram_insets}
\caption{Phase diagram of the transmission blockade breakdown in the steady state. The color map shows the cavity transmittance referenced to the resonant empty cavity transmission as a function of the cavity drive amplitude, $\eta$, and repumping rate, $\lambda$. The latter quantity is rescaled with a monotonically increasing function, $G \equiv (1 + 2 \Gamma/\lambda)^{-1}$, which tends to $G=1$ for $\lambda \rightarrow \infty$. The white stripe in the middle corresponds to the domain where the system of equations admits multiple stable solutions. There are distinct phases to the left and right of this boundary which are the blockaded and the bright states of the cavity field, respectively. }
\label{fig:PhaseDiagram}
\end{figure}

\begin{figure*}
\includegraphics[width=\linewidth]{multistability}
\caption{
 Cavity transmittance and atomic populations as a function of pumping rates. Transmission is first considered with respect to varying repump rates, with the cavity drive fixed at $\eta=300$, (a). Secondly, we consider transmission as a function of the cavity drive amplitude for fixed repumping rates $G=0.1$, (b), and $G=1$, (c). Similarly, the relative steady-state populations, $N_f$ (green), $N_e$ (blue) and $N_g$ (orange) are plotted with respect to the same pumping rates, (d-f). All the plots show a crossing of the bistability domain, represented by the white stripe, in Fig.~\ref{fig:PhaseDiagram} along a vertical, (a and d), and horizontal (panels (b), (c), (e) and (f)) axis. Where the control parameters, $\eta$ and $\lambda$, give rise to multiple solutions, the solid lines correspond to stable steady states and the dashed ones, unstable solutions.
  }
\label{fig:bistabcuts}
\end{figure*}

The transmittance exhibits the well-known S-shaped curve as a function of the cavity drive, known from classical optical bistability (cf. Fig.~\ref{fig:bistabcuts}(b) and (c)). There are two stable steady states and one unstable solution. In the present case of a three-level $\Lambda$ scheme, a similar multivalued domain occurs if the repumper power is varied, as shown in panel (a). This highlights the crucial role of the repumper and the third level $|f\rangle$ in the system. The distinctive feature with respect to the well-known case of optical bistability can be revealed by investigating the populations in the three atomic levels   in the steady-state solutions, shown in the bottom row of panels in Figs.~\ref{fig:bistabcuts}(d-f).  In the transmission-blockaded phase, the atoms are dominantly in the state $| g \rangle$, i.e. $N_g \gg N_f,\,N_e$ independently from the repumper and the cavity pump strength. When the blockade is broken down and there is a finite transmittance approaching unity, the populations strongly depend on the repumping rate.

In the low $\lambda$ limit ($\lambda \ll \Gamma$), the cavity photons optically pump the atoms to the other ground state $| f \rangle$, resulting in $N_f \gg N_g,\,N_e$ (see the bottom-right inset scheme in the phase diagram in Fig.~\ref{fig:PhaseDiagram}). This is the interesting limit of bistability, represented by Fig.~\ref{fig:bistabcuts}(e): the two stable steady states correspond to electronic ground states, $| g \rangle$ or $| f \rangle$, with high purity, and the cavity-transmitted photocurrent enables a direct monitoring of which ground state the atoms are in. Such a bistability, dubbed transmission-blockade-breakdown (TBB) \cite{clark_time-resolved_2021}, can be considered the extension of the photon-blockade-breakdown (PBB) phenomenon, known from single- or few-atom CQED \cite{carmichael_breakdown_2015,fink_observation_2017}, to many-atom CQED systems. Whereas with PBB, a large cooperativity ${\cal C}=  g^2/(\gamma \, \kappa)$ is needed on the single-atom level ($g\gg\kappa,\,\gamma)$, for TBB the large cooperativity ${\cal C}=  N g^2/(|\Delta_A| \, \kappa)$ is achieved by increasing the number of atoms ("collective strong coupling regime").

As a reference, we display the case of classical bistability \cite{Gibbs1976Differential,rosenberger_observation_1983,carmichael_quantum_1986} which is reproduced in the limit of $\lambda\rightarrow\infty$, $G\equiv (1+2\Gamma/\lambda)^{-1} = 1$, when the strong repumper confines the atomic state to the two-level manifold spanned by $| e\rangle$ and $| g \rangle$ (corresponding to the top-right inset scheme in Fig.~\ref{fig:PhaseDiagram})). Fig.~\ref{fig:bistabcuts}(f) shows that the bright cavity phase is connected to a full mixture of the atomic state $N_e \approx N_g$, while $N_f \approx 0$. This means that cavity photons saturate the atoms in the two-level manifold, while state $| f \rangle$ is effectively eliminated from the dynamics by the strong repumper. This model thus reveals that the control parameter $\lambda$ bridges the well-known saturable absorber optical bistability and the much more recent paradigm of first order dissipative phase transitions, that has been shown to be represented by the photon-blockade-breakdown bistability.

In the following, we present experimental results obtained from measurements on a CQED system which is more involved than the above-discussed abstract model. However, we will show that the main features of the interaction are properly captured by the model, and the phase diagram presented in Fig.~\ref{fig:PhaseDiagram} underlies the actual CQED system of the experiment.

\section{Experiment}
\label{sec:experiment}

An ensemble of cold ${}^{87}$Rb atoms was loaded into the mode of a high-finesse resonator by magnetically transporting the atoms from a magneto-optical trap (MOT) to the cavity. After the MOT cycle, the atoms were cooled by polarization gradient cooling down to temperatures of $T \approx 120 \mu$K. Subsequently, they are magnetically polarized by optical pumping into the $(F, m_F)=(2, 2)$ hyperfine ground state to allow capture with a magnetic quadrupole trap. The magnetically trapped atomic cloud was then transported into the cavity by  adiabatically displacing the trap center. The cavity is $l=15$ mm long and the mode waist was $w=127 \mu$m, an order of magnitude smaller than the atomic cloud in this direction. Approximately ${N} \sim 10^5$ atoms were loaded into the mode volume. The cavity linewidth was measured to be $\kappa=  2\pi \times 3.92$ MHz (HWHM), and the single-atom coupling constant was calculated as $g= 2\pi \times 0.33$ MHz on the $(F, m_F)=(2, 2) \leftrightarrow (3,3)$ hyperfine transition of the D2 line. A single mode of the actively stabilized resonator was resonantly driven, $\Delta_C = 0$, with a laser tuned  below the F=2 $\leftrightarrow$ 3 atomic resonance by $\Delta_A=-2\pi \times 29$ MHz. Along with a circularly polarized drive field, $\sigma^+$, the single-atom frequency shift was $\delta \approx 2\pi \times 3$ kHz, such that $N \approx 10^4$ relevant atoms could shift the mode by more than $10 \kappa$ from resonance.

A mapping between the abstract model of Eq.~(\ref{eq:meanfield}) and the actual level scheme of ${}^{87}$Rb is presented in Fig.~\ref{fig:Rb_levels}, together with the given configuration of laser drives. The state $|g\rangle$ corresponds to the hyperfine ground state $(F, m_F)=(2, 2)$ in ${5}^2{\rm S}_{1/2}$, whereas the excited state $|e\rangle$ is realized by $(F, m_F)=(3, 3)$ in ${5}^2{\rm P}_{3/2}$. This is a closed-cycle transition within the D2 line for $\sigma^+$ circular polarization. As the atoms are in a magnetic quadrupole trap, the magnetic field defining the local quantization axis varies in space. In the plane of the cavity mode, the magnetic field lies in the same plane, pointing radially outward from the trap center which coincides with the center of the cavity (Fig.~\ref{fig:geometry}). Therefore, the magnetic field is oriented, to a good approximation, parallel to the cavity axis within the mode. However, in the two halves of the mode volume, being on the two opposite sides of the mode center, the magnetic field is pointing in opposite directions. Therefore, the circularly polarized cavity drive field is effectively $\sigma^+$ in one half, and $\sigma^-$ in the other half of the mode volume with respect to the local quantization axis.

\begin{figure}
\centering
\includegraphics[width=0.66\linewidth]{level_repumper}
\caption{The ${}^{87}$Rb levels behind the simplified model in Fig.~\ref{fig:scheme}. Red arrows represent cavity field excitations and the green arrow the repumper. Other states in the hyperfine manifold with smaller magnetic quantum numbers are not shown.}
\label{fig:Rb_levels}
\end{figure}

\begin{figure}
\centering
\includegraphics[width=0.9\linewidth]{quantizationaxis}
\caption{Magnetic field lines and orientation with respect to the cavity axis (red lines representing the cavity mode waist in the x-y plane). In the x-z plane, the quadrupole trap creates field lines that bend away from the origin and that are cylindrically symmetric around the z axis (green lines). Perpendicular to this, within the x-y plane of the cavity axis (grey), the magnetic field lines (thin blue arrows) point radially outward. The quantization axis (thick blue arrows), within the cavity mode, is then parallel to the cavity axis but with opposite orientation in the two halves of the mode.}
\label{fig:geometry}
\end{figure}

The $\sigma^-$ polarized field generates transitions from $|g\rangle$ to the  $(F, m_F)=(2, 1)$ in ${5}^2{\rm P}_{3/2}$, which has a much smaller Clebsch-Gordan coefficient than the $\sigma^+$ transition (ratio $\tfrac{1}{15}$). Nevertheless, excitation to the $(F, m_F)=(2, 1)$ implies that the atoms can decay into $(F, m_F)=(1, 1)$ which is the state $|f\rangle$. The decay can also lead to the other hyperfine state $(F, m_F)=(1, 0)$. However, this state can be incorporated into $|f\rangle$. The coupling between the ground-state manifolds $F=1$ and $F=2$ includes a spontaneous emission process in both directions, therefore only the populations, not coherences between the states $|f\rangle$ and $|g\rangle$, $|e\rangle$ play a role. The repumper resonantly drives the transition from the $(F, m_F)=(1, 1)$ ground state to the $(F, m_F)=(2, 2)$ excited state with $\sigma^+$ polarized light, which amounts to an optical pumping into the state $|g\rangle$. This is considered as a population pumping with rate $\lambda$ in equation (\ref{eq:meanfield}).  The other simplification in the semiclassical model is that the population of $|f\rangle$ is loaded from the state $|e\rangle$  rather than introducing additional variables to describe the state  $(F, m_F)=(2, 1)$. The population in this latter is proportional to that of  $|e\rangle$, since both of them are excited by the cavity field from the state $|g\rangle$. Therefore, the crucial dependence on the cavity field intensity and the population in $|g\rangle$ is captured by the model with a phenomenological rate, $\Gamma$, determined previously as $\Gamma= 0.93 \times 10^{-3} \gamma$, by fitting the numerical simulation to the observed transition dynamics \cite{clark_time-resolved_2021}.

The mean-field model, appropriately accounting for the cavity-assisted optical pumping processes,  does not include the atom loss from the trap. The total atom number, ${N}$, in Eqs.~(\ref{eq:meanfield}) is not a conserved quantity. The loss is due to recoil heating, background gas collisions, etc. There are other processes which follow from the dynamics: when the atom is in state $|f\rangle$, the magnetic trap potential vanishes for the $(F, m_F)=(1, 0)$ and is repulsive for the $(1, 1)$ states. Because of the atom loss, the system ultimately evolves into the resonant empty-cavity transmission  on a slow timescale of a few 100 ms (cf. measurement results below).

\section{Driven-dissipative phase transitions}
\label{sec:dynamical}

The end of the atom transport into the cavity mode defines the time $t=0$. The cavity drive was switched on at $t=3$ ms at the chosen power level. The measurement signal is the cavity transmission recorded by an avalanche photodiode until $t=5$ s. In all the measurements, the atoms were initially in the ground state, $|g\rangle\leftrightarrow(F,m_F)=(2,2)$. Therefore, the transmission at the beginning of the interaction, with $N\sim 10^5$ atoms in state $|g\rangle$, was always suppressed by the dispersive shift of the mode with respect to the fixed drive frequency by more than ten times the linewidth. Depending on the strength of the cavity drive and that of the repumper, this state could be the stable phase or an unstable one, according to the phase diagram in Fig.~\ref{fig:PhaseDiagram}.

\begin{figure}
\includegraphics[width=\linewidth]{matrix_trans}
\caption{The time evolution of the system with respect to varying control parameters, as monitored by the cavity transmission. The cavity drive amplitude increases from left to right ($\eta /\gamma = 25, 117, 236$) and the repumping rate decreases from top to bottom ($\lambda/\gamma = 5.9 \times 10^{-3}, 0.85 \times 10^{-3}, 0.27 \times 10^{-3}$), such that $G=0.76$, $0.31$ and $0.13$, respectively. The dynamics of the transition between the blockaded phase (close to zero transmission) and the transparent steady-state (transmittance close to 1) illustrate different domains of stability in the selected time windows.}
\label{fig:TimeEvolution}
\end{figure}

Figure \ref{fig:TimeEvolution} shows the cavity transmission as a function of time for $3\times3$ different pairs of fixed values of the control parameters $\eta, \lambda$. The cavity drive strength $\eta$ increases from left to right, whereas the rescaled repumping rate $G$ increases from bottom to top.  The left column represents a weak cavity drive compared to the effect of the repumper. According to the phase diagram in Fig.~\ref{fig:PhaseDiagram}, the stable phase is the blockaded one with atoms in $|g\rangle$, which is the initially prepared state of the system. In this case, only atom loss can lead to the transparent cavity state. Indeed, the left column shows that the transition is independent of the repumper strength and takes place on a long timescale of about 350 ms. This timescale can be attributed to the situation that even atoms in state $|g\rangle$ were gradually lost from the trap, due to the above described mechanisms not contained in our idealized theoretical model of Sec. \ref{sec:two-way}. On increasing the cavity drive intensity (middle column of panels), an earlier and faster emptying of the trap can be observed. This indicates that the steady state is still the transmission blockade,  and the cavity drive merely increases the population in the states $|e\rangle$ and $|f\rangle$, thereby speeding up the atom loss.

Qualitatively different behaviour of the transition is depicted in the right column of panels where the cavity drive is strongest. For the bottom right panel, (i), the repumper drive intensity is so weak that the stable phase is the transparent resonator with atoms in $|f\rangle$. However, the system, initially, is prepared in the other, transmission blockaded phase with all atoms in $|g\rangle$. Before considerable atom loss can take place, the system undergoes a non-linear runaway process to transition into the stable phase. This is clearly the case in (i), and traces of this dynamics can be observed in (h). So the bottom row shows that the transition varies from an atom-loss dominated smooth transition (bottom left panel) to a phase-transition-like switch on increasing the intensity of the cavity drive. This effect has been thoroughly analysed in a recent paper \cite{clark_time-resolved_2021}.

The key new observation is represented mostly by panels Fig.~\ref{fig:TimeEvolution}(f) and (c). Rather than fast, monotonic switching to the stable phase, as in panel (i), stronger repumping leads to an oscillatory transition in (f) and, somewhat less clearly, in (c). The strong dynamical oscillations are indications of the competition of the opposing optical pumping processes. They appear only in a limited range of the control parameters for which, on losing atoms, the system goes into the bistability region of the phase diagram. However, when monitoring the transmitted intensity, the effect of bistability is partly covered by  atom loss. One can unravel the dynamical signatures of the transition which are beyond the effects of the atom loss by analyzing the intensity fluctuations. An alternative method, which we present in the next section, is to vary the system parameters on a timescale shorter than that of the loss.

\begin{figure}
\includegraphics[width=\linewidth]{matrix_thph}
\caption{The excess noise (in cavity photon number) accompanying the transitions in Fig.~\ref{fig:TimeEvolution}. When the control parameters are in the bistability domain, the single-mode cavity field manifests significantly enhanced fluctuations during the transition between the steady-states.}
\label{fig:ThermalPhotons}
\end{figure}
The bistability is confirmed by the increased intensity of fluctuations in the  detected transmitted signal when the system transitions between  phases. The single-mode cavity field is considered as a displaced thermal (chaotic) state for which the width of the intensity distribution can be characterized by a thermal photon number. This latter can be inferred from the recorded intensity noise following the procedure described in Ref.~\cite{clark_time-resolved_2021}. The excess noise corresponds to fluctuations of the mean-field amplitude, $\alpha$, and is thus beyond the scope of the mean-field model.

The atom-loss dominated transition to the transparent phase (left column of panels) does not exhibit excess noise during the transition (note that the initial fluctuations including even negative photon numbers in panel Fig.~\ref{fig:ThermalPhotons}(a), (d), and (g) indicate the finite accuracy of the method close to zero mean value of the field, i.e., uncertainty is below 0.5 photon). There is some excess noise generated during the transition with increased $\eta$ (middle column), while significantly enhanced intensity fluctuations accompany the transition for strong cavity drive (right column). An equivalent of 20 and 100 thermal photons characterize the width of the photon number distribution in the cavity mode during the limited time period when the system is in the transmission blockade breakdown and the bistability region, Figs.~\ref{fig:ThermalPhotons}(i) and (f), respectively. This is comparable, but in addition to the Poissonian noise of about 100 photons at the observed mean photon number around $10^4$ (see Fig.~\ref{fig:TimeEvolution}).

\begin{figure}
\centering
\includegraphics[width=0.81\linewidth]{exp_fit}
\caption{The magnitude of the excess noise (in thermal cavity photon number) with respect to the cavity drive power (empty cavity photon number). Different colours correspond to different repumper strengths, $G = 0.127$ (blue), $0.144$ (orange), $0.542$ (green), $0.632$ (red) and $0.708$ (purple).  Each point represents the average of ten measurements. The linear fits in the log-log scale reveal power laws with exponents $1.19\pm0.15$, $1.58\pm0.11$,  $2.73\pm0.27$,  $2.68\pm0.11$ and  $2.49 \pm0.36$, respectively.}
\label{fig:Exponent}
\end{figure}
The enhancement of fluctuations depends systematically on the control parameters. For example, consider the rows of Fig.~\ref{fig:ThermalPhotons} in which only the cavity drive varies. Expressing this enhancement in terms of a thermal photon number, it shows a power law dependence  on the cavity drive as seen on the log-log plot in Fig.~\ref{fig:Exponent} where the drive is also expressed as the  photon number the drive  would generate in an empty cavity. The exponent varies with repumper strength  (numerical values given in the figure caption). A deeper theoretical interpretation of  this experimental observation requires the description of higher-order quantum correlations in the atom-light interaction, which is beyond the scope of the mean-field approximation of the Heisenberg--Langevin equations and will be studied elsewhere.

\section{Hysteresis}
\label{sec:hysteresis}

As suggested above, the atom number, ${N}$, evolves in time due to loss processes not included in the theoretical model. As such, these changes are not reflected in the phase diagram of Fig.~\ref{fig:PhaseDiagram}. As atoms are being lost, the bistability domain of the diagram shifts toward smaller cavity drive strengths, i.e. the transmission-blockaded phase gradually shrinks. Nevertheless, the atom loss process is slow enough that the multistability of the system is still apparent to fast varying probe light, in the form of hysteresis \cite{rodriguez_probing_2017}.

\begin{figure}
\centering
\includegraphics[width=0.76\linewidth]{sci_hyst} \raisebox{0.5cm}{\includegraphics[width=0.22\linewidth]{PhaseDiagramRampEta}}\\
\includegraphics[width=0.76\linewidth]{rep_hyst} \raisebox{0.5cm}{\includegraphics[width=0.22\linewidth]{PhaseDiagramRampLambda}}
\caption{Hysteresis in the cavity transmittance when the cavity drive power, (a), and the repump power, (b), sweep across the bistability domain back and forth five times. The corresponding sweep axis in the phase diagram is shown in the small panels to the right. The temporal order of the ramps is indicated by the blue, orange, green, red and purple lines, respectively and the ramp direction by the arrows. For (b), we use a $\log_{10}$ scale. }
 \label{fig:Hysteresis}
\end{figure}
To this end, the control parameters were swept repeatedly across the bistability domain. The intensities were varied using an acusto-optical modulator (AOM), ramping the drive voltage up and down linearly. For the cavity probe laser, $\eta$, the ramp times were 30 ms up, and 10 ms down, while for the repumper, the corresponding values were 15 and 5 ms, respectively.  Fig.~\ref{fig:Hysteresis} presents the cavity transmission for ramping, (a), the cavity drive and, (b), the repumper intensity five times, while the other control parameter was kept fixed. The atoms were initially prepared in state $|g\rangle$, so the cavity transmission was initially suppressed. The first ramping cycle of the cavity drive did not move the system out of this phase (cf.~Fig.~\ref{fig:Hysteresis}a) because even if this phase becomes unstable for high cavity drive, when the bistability domain is crossed during the ramp, the transition from such a steady state takes place randomly on a long timescale. At this first ramp, it happened to be longer than the sweep period. During the second ramp-up (orange curve), the transition to the transparent phase, atoms in $|f\rangle$, did occur. Hence, during the ramp-down, there is a higher cavity transmission at the same drive strength. This is persuasive evidence of bistability. It is only at the  end of the ramp down period that the repumper transfers the atoms back to state $|g\rangle$, reinstating the blockaded phase. At the beginning of the next ramp up period (green), this is still the ongoing direction of optical pumping until the cavity drive starts to dominate. Accordingly, the corresponding transmission curve (green) is slightly below that of the preceding ramp-down period (orange). This ramp cycle, with the same features, could be observed three more times before the atoms were lost from the cavity. Where we reemphasize that the hysteresis window shrinks for consecutive cycles due to the decreasing number of atoms.

The hysteresis was confirmed by varying the repumper intensity, as a control parameter, with cavity drive fixed. Considering the transition across the bistability domain, the  repumper powers are widely varied that a logarithmic scale is used on the horizontal axis. In Fig.~\ref{fig:Hysteresis}(b) the curve starts at the large repumper limit, where the initial state of atoms in $|g\rangle$ corresponds to the stable phase. Within a sweep cycle, the value of the repumper power was below the bistability domain for short times only. Therefore,  the transition to the states $|f\rangle$ did not happen in the first cycle (blue) but only in the second one (orange). In this cycle, a partial population transfer to the states $|f\rangle$ was accomplished within the ramp-down time and a part of the atoms remained in the blockading state $|g\rangle$. The cavity transmission increased noticeably, but to a value well below the empty cavity reference.  At subsequent cycles, the atom number was smaller due to loss, and a full transfer from the state $|g\rangle$ to $|f\rangle$  has been achieved during the period where the repumper intensity was decreased  below the bistability domain. At these smaller atom numbers, on the other hand, the mode frequency shift did not reach the level necessary to suppress the transmission. Therefore, the red and purple curves do not go down to zero for strong repumper at the right side of the plot. Nevertheless, hysteresis was clearly observed in these cycles, implying the presence of bistability.

\begin{figure}
\centering
\includegraphics[width=0.95\linewidth]{rep_norep_pulses_legend}
\caption{The time evolution of the cavity transmission without repumping (blue), with repumping (green) and with pulsed repumping (orange).
When the repumper is switched off, the system starts to evolve in a runaway process toward the bright phase at a given time near $t=0.04$s. With the repumper on however, the system undergoes the transmission blockade breakdown at a later time than without it. As the repumper is strong in this case, the transition to the high transmittance phase, with atoms in state $|f\rangle$, takes place only when the atom number is significantly reduced due to other loss processes. With pulsed repumping, the transition occurs every 5 ms, because the repumper brings the atoms back from state $|f\rangle$ to state $|g\rangle$ (the blockaded phase): switching between the two hyperfine ground states.
}
\label{fig:RepumperRole}
\end{figure}
Finally, we performed a measurement in order to outline the role of the repumper and to detect the atomic state in the transparent phase. The repumper was pulsed between zero and a large value, $G=0.44$, with a period of 5 ms (on/off ratio 1). The time evolution of the cavity transmission is plotted in Fig.~\ref{fig:RepumperRole}, where the blue curve represents the evolution of the system without repumping, while green gives the transmission with constant repumping, for the same value of $G$. These configurations correspond qualitatively to the (i) and (c) panels of Fig.~\ref{fig:TimeEvolution}, respectively. In the prior case, the system with atoms in $|g\rangle$ is prepared in a phase which is unstable at finite cavity drive and without repumper. Therefore the system switches to the stable phase in a runaway process at a random time. With repumper on, the blockaded phase is stabilized to some extent, and the runaway transition is delayed until fewer atoms are present, due to loss. The observed curve for the pulsed repumper demonstrates that the atoms can be transferred back to the state $|g\rangle$ by means of the repumper. The considered timescale is not so long as to have significant atom loss during the period of the plot. Therefore, the blockade can be reinstated repeatedly, following the pulse sequence exactly. This shows that the cavity transmission blockade was broken down by shelving the atoms into the state $|f\rangle$ rather than by an atomic saturation effect.

In addition, this measurement served for the calibration of the model parameter, $\lambda$, characterising the AOM-controlled repumper intensity. When there is a sudden increase of the cavity transmittance (repumper is off), the magnitude of its change gives information on the depletion of the population in $|g\rangle$. One can safely assume that these atoms are accumulated in the state $|f\rangle$. On switching on the repumper, from the initial slope of the transmittance drop, it is possible to deduce the rate of change in the population of $|f\rangle$. It is given by $-\lambda N_f$, according to the last term in Eqs.~(\ref{eq:meanfield}), from which the rate $\lambda$ can be obtained.

\section{Conclusion}
\label{sec:conclusion}

We have experimentally demonstrated bistability in a cold atom-cavity QED system, where the steady states correspond, dominantly, to hyperfine ground states. Having explored the runaway pumping processes involved, we described the phenomenon in terms of a driven-dissipative phase transition, with two optical driving intensities as control parameters and cavity transmission as the order parameter of the system.
Crucially, by exploring different combinations of optical pump intensities, we showed that the steady state of the system depends on the history. This observed hysteresis, in both control parameters, not only confirms the bistability but that the transition is a first-order effect. In fact, for high pumping intensity in one of the control beams, we recover the original, widely known, optical bistability, such that our system encompasses this effect as a special case.

Considering future directions, we note that the system size is characterised by the cooperativity, i.e., the collective coupling strength between the atomic cloud and the cavity mode. In our system, the cooperativity, ${\cal C}$, was about 100 which is comparable with the one reached in the circuit QED systems with single artificial atoms \cite{fink_observation_2017}. However, in this $\Lambda$ atom scheme,  the cooperativity can be increased by the number of atoms, so one can better approach the thermodynamic limit. One possible solution is to use Bose condensed gases, for which the steady-states would be entirely quantum in all degrees of freedom. Beyond this, the observed effect is also a promising step towards realising first-order quantum phase transitions. As the cavity transmittance is associated with hyperfine states, which can be coherently manipulated with microwave radiation, the system shows analogy with single-atom based quantum switches \cite{davidovich_quantum_1993} and quantum birefringence systems \cite{turchette_measurement_1995}. Within a many-body systems, the observed effect suggests a pathway for bringing microscopic quantum effects to a mesoscopic system size.

\section*{Acknowledgements}

We thank J. Fort\'agh, \'A. Kurk\'o and N.~N\'emet for useful discussions. This work was supported by the National Research, Development and Innovation Office of Hungary (NKFIH) within the Quantum Information National Laboratory of Hungary.

redpajama_set_name: RedPajamaArXiv


text:
Home Sports ap_sports Bourdais ends long winless drought in Toronto
ap_sports
Bourdais ends long winless drought in Toronto
TORONTO (AP) — Sebastien Bourdais waited out the rain, then took care of a winless drought.
Bourdais dominated from the pole at Toronto in the first IndyCar Series race of a Sunday doubleheader,
cruising to his first open wheel victory since 2007.
The race was shortened to 65 laps after rain wiped out Saturday's race. Another 65-lap race was set for
the afternoon at Exhibition Place.
Bourdais, in his first season with KVSH Racing, made it to the podium for the first time this year. He
finished second and third on this track in two races last year. Bourdais won his first pole since 2007
and now has his first victory since the 2007 Champ Car season finale in Mexico City.
He has 32 career open wheel wins and this is his first in 53 races under the IndyCar banner.
"It just went perfect from green to checkered flag," Bourdais said.
This was KVSH Racing's first victory since Tony Kanaan won the 2013 Indianapolis 500.
Bourdais stood on his car and raised his arms. He hugged his wife and two children who weren't born when
he was the class of Champ Car. Owners Kevin Kalkhoven, Jimmy Vasser and James Sullivan greeted him with
hugs and smiles.
"Hopefully, there's more of that to come," Vasser said. "When he gets on a roll, he's
unbeatable."
It's hard to know that in the IndyCar era. But in Champ Car, Bourdais long reigned supreme. He won four
consecutive Champ Car titles from 2004 to 2007. But he left American open-wheel racing for Formula One
following his fourth Champ Car title, and he never came close to posting the same success.
His win moved him into eighth on the career open-wheel list.
Of Bourdais' 32 victories, 15 are on road courses and 13 are on street courses. He's also won on three
ovals — twice at Las Vegas and once at Milwaukee.
His win also means he beat Kanaan to checkered flag this season. Kanaan and KVHSH Racing parted ways
after last season.
Helio Castroneves was second and Kanaan was third to complete the podium. Castroneves had his sixth
podium finish of the season and Kanaan, his first.
Castroneves stretched his lead in the points race to 28 over Will Power. He'll start from the pole in the
second race.
Bourdais, who entered 12th in the points race, was the second driver to win from the pole this season.
"It's reinvigorating," Vasser said. "I think there's more to come. I really think this is
the beginning of more wins."
Bourdais can make it a sweep later in the day if he can come back to win from the middle of the pack.
If so, the only question will be, how to celebrate: With some champagne for the Frenchmam Bourdais or
some wine from Vasser's V12 Vineyards winery?
Either way, it's a win worth savoring.
Once the race finally got going, no driver could touch Bourdais.
The last IndyCar Series race postponed because of rain was in Sao Paulo, Brazil, in 2011. That race ran
its first 15 laps on Sunday, May 1 and concluded with 40 laps on May 2. The last race to be postponed in
full was at St. Petersburg, Florida, on March 28, 2010. The race was run March 29, 2010.
Sunday's first race came to an almost immediate halt when a multicar crash led to a red flag on the
opening lap. After a long delay — and more sitting for the drivers after Saturday's rain delay — racing
resumed with Bourdais leading the field to green. He never really had to look back.
"It's really sweet. It was one where the stars aligned," Bourdais said. "Last year we were
second and third, and it's great to get this win."
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"Into my Darkened Home" is a drama about Sara, a 18 year old Norwegian-Kurdish girl, who is in a secret relationship with Erik. Sara lives a double-life, but after her parents discovers her relationship with Erik, she is restrained from him and all her previous privileges. Sara wants to live a life as a Norwegian girl in Norway, now she wants to break out of her family. This is hard for her as it affects her families honor, and the safety of her boyfriend Erik, it gets even harder when her parents makes her leave the country to mary her cousin in Kurdistan. Sara is pushed into a corner and has to make a decision, break away from her family or preserve the family honor.


I spoke with the Transplant Coordinator at West Penn yesterday, and the testing from all three donors is in now. All three of these match on 10 of 10 HLA (DNA) categories. All are three are female; two are younger, one is older (described as "under 50" still); two are international, one is domestic. Their blood type and age will be considered in the decision. Doctors should decide soon now. And it could be 3-6 weeks till Beth starts her conditioning regimen.


This is a great clinic. I can recommend the naturopath and his treatments.
PS As a fellow naturopathic practitioner and fellow student with Paul, He Is An Awesome Naturopath !
These are among the most common health complaints that people live with every day, and if left untreated, can lead to more serious problems that affect the health of the whole body.
1.	Maintaining the integrity of the gut lining.
2.	Having a healthy balance of bacteria in the gut.
3.	Adequate digestive enzyme function.
If one of these areas is out of balance, it will impact on digestion and overall health.
The lining of the Gut is made up of several layers of cells and a mucous barrier. The Gut is the only internal part of your body that is exposed to the outside world.
Damage the lining of your gastrointestinal tract.
Glutamine is an amino acid that helps to repair the gut lining after trauma from infections, food intolerances and medications.
Roughly 400 species of Probiotic bacteria live inside a healthy digestive tract. There are more beneficial bacteria living in your digestive tract than you have cells in your body.
Protos is Greek meaning 'before'. Bios is Greek meaning 'life'.
The digestive process is highly dependent on the balance of beneficial bacteria in the digestive tract. These Probiotic organisms form a symbiotic relationship with our bodies, helping with the digestion of food and the regulation of the whole body's immune system.
Fermented foods are the best way to maintain your Guts Probiotic population. Though, there are cases where it is necessary to take a specific strain of bacteria.
Your body creates enzymes to do a multitude of functions, including the breakdown of food.
Hydrochloric Acid is made by the cells in the stomach. Without adequate Hydrochloric acid in the stomach further digestion of some nutrients in the small intestine is impossible. It also kills bad bacteria before they can infect the intestines.
Bile is made by the cells of the Liver. It is an emulsifying agent breaking down the fats that we eat.
Pancreatic Enzymes: these enzymes digest proteins, fats and carbohydrates in the small intestine.
It may be necessary to supplement one or all of these enzymes to get your Gut digesting food properly.
Do you base your food choices on the benefits they will provide?
Here are some key guidelines for Gut Health.
·	Reduce as much as possible refined, processed and fast foods. Restrict sugary foods, cakes, lollies, soft drinks, bottled juices, ice creams and pastries.
·	Limit starchy carbohydrates to one serve daily and include protein rich foods at every meal and snack.
·	Eat fresh and organic as much as possible, choosing one serve of fresh fruit and at least three cups of fresh vegetables daily.
·	Include healthy oils, nuts and seeds in your diet.
·	Drink plenty of clean water, a minimum of eight glasses per day and avoid excess alcohol, and caffeine.
Certain digestive disorders require a more specific approach. If you have a digestive condition, a tailored diet and supplementation will be beneficial for you.
If you are suffering from digestive symptoms, your gut is not 100% and is preventing you from being your optimal self.
Naturopath and Remedial Massage Therapist.


Weddings are lots of fun! You are about to join in matrimony with another person and live with him or her for the rest of your life. Most people have planned this day out their whole lives. These paragraphs are designed to offer useful tips on building the wedding you both want.
TIP! Practice walking down the aisle as much as you can right before the wedding. Also, practice it at the wedding venue in the shoes you plan on wearing.
One thing you need to think about during the wedding planning process is what alcohol will be served, and how much you want to spend on it. Having an open bar can be very expensive if it stays open for hours. Ask your venue about the different alcohol serving options that they have available.
If you're catering your own event, try purchasing the food from wholesale stores. When you shop this way, you can buy your food cheaper than at regular retailers. See if your friends can chip in for food costs.
TIP! Flowers are great, but don't place too many of them on your tables or they can become tacky. Flowers can be distracting for your guests and get in their way.
TIP! Do your research when it comes to your photographer. Having a photographer take pictures you do not like would be a shame.
You may want to utilize ethnic dishes for a unique reception. Steak and chicken are both overrated, not to mention boring. Variety is the spice of life and it is sure to make your wedding dinner something to remember!
TIP! Those brides that are lovers of fashion and luxury can have bouquets embellished with rhinestones, diamonds, or Swarovski crystals. You can achieve this look by using heat-fixed or adhesive crystals or small pieces of costume jewelry.
Brides who want to sparkle might like to add some flashy stones to their bouquet, including rhinestones, Swarovski crystals, and even diamonds. This can be achieved through heat-fixed crystals, adding a little piece of jewelry or even using an heirloom piece. To make sure that it matches well with your ensemble, you need to be consistent when it comes to the size, cut and the color of the stones.
If you have a destination wedding and your family is there, see if they want to stay for the honeymoon. Everyone can save money by staying longer, as hotels will give you great discounts for longer stays. This allows them to celebrate your wedding with you and have a great vacation afterwards!
TIP! If money isn't an issue, you may want to get married on a cruise ship with close members of your family and close friends. Your honeymoon will start right after the ceremony.
Avoid having your guests standing around waiting while you have your pictures taken. Try to take as many photos as you can before the ceremony begins. Pictures of the parents with the bride and groom are also able to be shot beforehand and reduce the wait time for the guests at the reception.
TIP! See if a friend has something they wouldn't mind letting you wear for your wedding. A nice bracelet or necklace will both complete your look, as well as give you "something borrowed" for the day.
Are you ready to get started planning your wedding? A wedding is an exciting time. It is a time to celebrate two people sharing their lives together. Planning a wedding is no easy task, there are a lot of details that need to be planned and remembered. Use the helpful advice you read here to help ensure your special day is perfect. Congrats on your wedding and best of wishes to you!


Swede Joakim Lagergren will take a commanding six-shot lead into the final round of the Northern Ireland Open Challenge at Galgorm Castle.
One ahead overnight, Lagergren's 66 extended his lead to six over Dutchman Tim Sluiter, England's Max Orrin and South African Brandon Stone.
Jonathan Caldwell is the leading Northern Ireland player on six under - seven behind Lagergren - after a 69.
Lurgan man Gareth Shaw is a further shot back on five under after his 69.
Both Northern Irishman are within three shots of second spot but the tournament now very much looks like Lagergren's to lose after the Swede produced an admirably composed round on Saturday.
Englishman Steven Brown caught Lagergren, 22, with a second-hole birdie but four birdies in six holes from the fourth then put the Stockholm native three ahead by the turn.
Lagergren, who hit a course record 62 on Thursday, wobbled as he bogeyed the long 10th and difficult par-four 11th but birdies at the 12th and 15th had the 22-year-back back in firm control.
Chasing his first Challenge Tour triumph, Lagergren picked up a further shot at the last for good measure to extend his lead to six.
Brown dropped out of second spot as he suffered three back-nine bogeys and now shares fifth spot with his fellow Englishman Charlie Ford, Welshman Rhys Davies and France's Adrien Bernadet.
World number 957 Lagergren's best Challenge Tour finish this year is a share of 19th at the St Omer event in France in June although he did make the cut at last week's Czech Masters on the main tour when he eventually finished 81st after disappointing closing rounds of 76 and 79.
Lagergreen finished 86th in the Challenge Tour rankings in 2011 but played mostly on the main tour in 2012 and 2013 as he achieved 140th and 144th positions in the Race to Dubai.
His best career-finish on the Challenge Tour is a sixth place at the 2011 Norwegian Challenge but he will considerably improve on that if he holds his nerve in Ballymena on Sunday.
Caldwell regrouped well from two dropped shots in his opening six holes to fire a two-under-par round which leaves him in a six-way tie for ninth spot.
Shaw is a further shot back on five under, tied for 16th spot but was left rueing a bogey at the closing hole after he was forced to take a penalty drop.
Ballymena amateur Dermot McElroy's hopes of emulating his top-10 finish from last year evaporated as he carded a 74 to drop to two over while Irish Close Champion John Ross Galbraith is two shots further back after a 75 on Saturday.
Italy's Niccolo Quintarelli produced the round of the day with a seven-under 64 which moved him up from the cut line of two over to sharing 16th with Shaw.
Three-time European Tour winner Johan Edfors is tied for 36th spot going into the final round after firing a 69 on Saturday.
On Friday, tournament ambassador Michael Hoey missed for the cut in the event for the second successive year after a 75 left him on four over.


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Listen to What Darth Vader Sounded Like On the Star Wars Set
BY Chris Higgins
Star Wars © & TM 2015 Lucasfilm Ltd. All Rights Reserved.
The voice of Darth Vader, provided by James Earl Jones, is one of the most iconic aspects of the original Star Wars movies. But James Earl Jones wasn't the actor wearing that outfit—it was British actor David Prowse, who was cast in part because he was huge (reportedly 6'5" and a former body-building champion).
George Lucas always intended to replace Prowse's voice, but it's still a bit of a shock to hear a muffled British voice coming out of Darth Vader's helmet. Here's video showing what Darth Vader sounded like on the set before James Earl Jones re-recorded the dialogue.
entertainment fun Movies News Pop Culture star-wars video
Attention Movie Geeks: Cinephile Is the Card Game You Need Right Now
BY Jay Serafino
Cinephile/Amazon
If you've got decades worth of movie trivia up in your head but nowhere to show it off, Cinephile: A Card Game just may be your perfect outlet. Created by writer, art director, and movie expert Cory Everett, with illustrations by Steve Isaacs, this game aims to test the mettle of any film aficionado with five different play types that are designed for different skill and difficulty levels.
For players looking for a more casual experience, Cinephile offers a game variety called Filmography, where you simply have to name more movies that a given actor has appeared in than your opponent. For those who really want to test their knowledge of the silver screen, there's the most challenging game type, Six Degrees, which plays like Six Degrees of Kevin Bacon, with the player who finds the fewest number of degrees between two actors getting the win.
When you choose actors for Six Degrees, you'll do so using the beautifully illustrated cards that come with the game, featuring Hollywood A-listers past and present in some of their most memorable roles. You've got no-brainers like Uma Thurman in Kill Bill (2003) and Arnold Schwarzenegger in Total Recall (1990) alongside cult favorites like Bill Murray from 2004's The Life Aquatic with Steve Zissou and Jeff Goldblum in The Adventures of Buckaroo Banzai Across the 8th Dimension (1984). Of course, being a game designed for the true film buff, you'll also get some deeper cuts like Helen Mirren from 1990's The Cook, the Thief, His Wife & Her Lover and Sean Connery in 1974's Zardoz. There are 150 cards in all, with expansion packs on the way.
Cinephile is a labor of love for Everett and Isaacs, who originally got this project off the ground via Kickstarter, where they raised more than $20,000. Now it's being published on a wider scale by Clarkson Potter, a Penguin Random House group. You can get your copy from Amazon now for $20.
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