Title and Abstracts of Keynote Speakers Prof. Dr. Edward Farhi: Quantum Money from Knots Money, either in the form of bills or information on a computer, should be impossible to copy and also verifiable as good money when tendered to a merchant. Quantum mechanics may make this possible to achieve with far greater security than can be achieved without quantum mechanics. Ideally Quantum Money is a cryptographic protocol in which a mint can produce a quantum state, no one can copy the state, and anyone (with a quantum computer) can verify that the state came from the mint without sending the money back to the mint. I will discuss Quantum Money generally and present our scheme based on quantum superpositions of diagrams that encode knots. This scheme is hopefully secure against computationally bounded adversaries and has not yet been broken. Quantum Money may be the basis of E-commerce on a future quantum internet and would not require communication with a central server such as a credit card company. Dr. Hadzibabic: Effects of interactions on Bose-Einstein condensation of an atomic gas I will discuss a series of recent experiments in which we studied various effects of interactions on the condensation of a dilute trapped atomic gas. First, we experimentally scrutinised the concept of purely statistical saturation of the thermal component as the driving mechanism for condensation [1]. We show that under usual experimental conditions ultracold atomic gases actually show strong deviation from Einstein's saturation picture, but saturation is recovered in the limit of vanishing interactions. Second, we experimentally observed for the first time the long-sought beyond-mean-field interaction shift of the critical temperature of a trapped gas [2], and related our measurements to the universal results obtained by Monte-Carlo calculations for a uniform system [3]. Finally, I will present some very recent measurements of condensation dynamics following a quench of the interaction strength. [1] N. Tammuz et al., PRL 106, 230401 (2011). [2] R. P. Smith et al., PRL 106, 250403 (2011). [3] R. P. Smith et al., PRL in print (2011), arXiv:1106.6295.
Title and Abstracts of Keynote Speakers Prof. Dr. Edward Farhi: Quantum Money from Knots Money, either in the form of bills or information on a computer, should be impossible to copy and also verifiable as good money when tendered to a merchant. Quantum mechanics may make this possible to achieve with far greater security than can be achieved without quantum mechanics. Ideally Quantum Money is a cryptographic protocol in which a mint can produce a quantum state, no one can copy the state, and anyone (with a quantum computer) can verify that the state came from the mint without sending the money back to the mint. I will discuss Quantum Money generally and present our scheme based on quantum superpositions of diagrams that encode knots. This scheme is hopefully secure against computationally bounded adversaries and has not yet been broken. Quantum Money may be the basis of E-commerce on a future quantum internet and would not require communication with a central server such as a credit card company. Dr. Hadzibabic: Effects of interactions on Bose-Einstein condensation of an atomic gas I will discuss a series of recent experiments in which we studied various effects of interactions on the condensation of a dilute trapped atomic gas. First, we experimentally scrutinised the concept of purely statistical saturation of the thermal component as the driving mechanism for condensation [1]. We show that under usual experimental conditions ultracold atomic gases actually show strong deviation from Einstein's saturation picture, but saturation is recovered in the limit of vanishing interactions. Second, we experimentally observed for the first time the long-sought beyond-mean-field interaction shift of the critical temperature of a trapped gas [2], and related our measurements to the universal results obtained by Monte-Carlo calculations for a uniform system [3]. Finally, I will present some very recent measurements of condensation dynamics following a quench of the interaction strength. [1] N. Tammuz et al., PRL 106, 230401 (2011). [2] R. P. Smith et al., PRL 106, 250403 (2011). [3] R. P. Smith et al., PRL in print (2011), arXiv:1106.6295.
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