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Prof. Peter Hannaford “Talk on quantum time crystals”
September 23, 2019 @ 10:00 am
Creating Time Crystals with a Ultracold Atoms
Centre for Quantum and Optical Science, Swinburne University, Melbourne, Australia
Time crystals are an exotic form of quantum matter in which a periodically driven quantum many-body system spontaneously self-organizes its motion and repeats itself in time, rather than in space, with a period longer than the driving period, allowing the periodic structure to resist fluctuations and to persist for long periods of time.
I will report on an experiment we are constructing in Melbourne to realize a discrete time crystal using a BEC of potassium-39 atoms bouncing on an oscillating atom mirror. In the absence of interactions, each bouncing atom performs irregular classical motion in which there are resonant islands in phase space located around periodic orbits whose periods match an integral multiple s of the driving period T of the mirror. In the presence of a sufficiently strong attractive interaction, the Floquet eigenstates of the periodic system become Schrödinger cat-like states, so that measurement of the position of just a single atom is sufficient to break the time-translation symmetry and collapse the system into one of the s wave-packets bouncing with period sT. Such a system allows dramatic breaking of discrete time translation symmetry where the symmetry-broken state evolves with a period typically s=40 times longer than the driving period. This system provides a platform for investigating a wide range of non-equilibrium condensed matter phenomena in the time domain.