<p>The initial detections were made without using squeezed light.</p>
<p>Squeezed light was introduced in <a href="https://www.ligo.caltech.edu/news/ligo20191211b" rel="nofollow noreferrer">early 2019</a>. It has the effect of increasing the detection sensitivity by about 15% above 50 Hz (<a href="https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.123.231107" rel="nofollow noreferrer">Tse et al. 2019</a>). Since gravitational wave strain scales inversely with distance, this expands the surveyed volume by about 50%.</p>

CC BY-SA 4.0
2021-07-14T01:06:27.430Z
Though the performance improvement is not *astronomical*, the upgrade in the underlying technology sounds *[generational](https://astronomy.stackexchange.com/a/43536/7982)!* :-)
uhoh
CC BY-SA 4.0
2021-07-13T23:17:35.857Z
2021-07-13T23:17:35.857Z
ProfRob
<p>This article from 2010 titled <a href="https://www.nature.com/articles/ncomms1122" rel="nofollow noreferrer">Quantum metrology for gravitational wave astronomy</a>, 6 years before the announcement of the first direct detection of gravitational waves from a binary black hole merger, states that:</p>
<blockquote>
<p>Recent advances in quantum metrology may now contribute to provide the required sensitivity boost. The so-called squeezed light is able to quantum entangle the high-power laser fields in the interferometer arms, and could have a key role in the realization of GW astronomy.</p>
</blockquote>
<p>My question: is that what happened? Are squeezed states of light used in the LIGO laser cavities? If so, did they lead to a boost in detector sensitivity that allowed for the ensuing detections?... or is it instead likely that the detections might have occurred without this application of squeezed light states?</p>

<gravitational-waves><quantum-mechanics><ligo>
Was quantum metrology important for gravitational-wave astronomy?
Daddy Kropotkin
# Was quantum metrology important for gravitational-wave astronomy?

(Asked by: username_0 on 2021-07-13)

This article from 2010 titled [Quantum metrology for gravitational wave astronomy](https://www.nature.com/articles/ncomms1122), 6 years before the announcement of the first direct detection of gravitational waves from a binary black hole merger, states that:

> Recent advances in quantum metrology may now contribute to provide the required sensitivity boost. The so-called squeezed light is able to quantum entangle the high-power laser fields in the interferometer arms, and could have a key role in the realization of GW astronomy.

My question: is that what happened? Are squeezed states of light used in the LIGO laser cavities? If so, did they lead to a boost in detector sensitivity that allowed for the ensuing detections?... or is it instead likely that the detections might have occurred without this application of squeezed light states?

**Tags:** gravitational-waves, quantum-mechanics, ligo

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## 1 answers

### Answer by username_1 on 2021-07-13. Score: 1 | Accepted answer

The initial detections were made without using squeezed light.

Squeezed light was introduced in [early 2019](https://www.ligo.caltech.edu/news/ligo20191211b). It has the effect of increasing the detection sensitivity by about 15% above 50 Hz ([Tse et al. 2019](https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.123.231107)). Since gravitational wave strain scales inversely with distance, this expands the surveyed volume by about 50%.

> **Comments:**
> **username_2**: Though the performance improvement is not *astronomical*, the upgrade in the underlying technology sounds *[generational](https://astronomy.stackexchange.com/a/43536/7982)!* :-)  

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