Next CQD special seminar will be given by Victor Gondret, Université Paris-Saclay
Please note the special place and time:
When: Monday, the 19th of May, 16:00 p.m.,
Where: KIP, INF 227, SR 2403
He will talk about:
Quasi-particle entanglement in a Bose-Einstein condensate : an acoustic analog of the Dynamical Casimir Effect
Parametric resonance is a recurrent phenomenon in physics, observable at all scales. For example, the vibration of a mirror in a cavity leads to the production of photons, a phenomenon known as the dynamical Casimir effect. In 1831, Faraday observed that a container of water excited vertically in a sinusoidal manner generates patterns with a frequency that is half of the excitation frequency. In the primordial universe, after inflation, parametric oscillations of a field (the inflaton) led to the creation of particles from vacuum, whose thermalization subsequently gave rise to the hot, dense state often associated with the Big Bang.
The growth in the number of quasi-particles (or particles) in the excited mode(s) is triggered by the system’s fluctuations and, due to momentum conservation, quasi-particles are created in pairs in two modes of opposite momentum. At zero temperature, quantum fluctuations initiate this growth, but when the temperature is non-zero, both thermal and quantum fluctuations trigger the growth. In this case, the characteristic signature of quantum vacuum fluctuations is then carried by the entanglement between these modes.
In this seminar, I will report on the experimental observation of the growth and decay of quasi-particle in a parametrically excited Bose-Einstein condensate. I will also discuss the evolution of two-mode entanglement between the quasi-particles and its subsequent disappearance due to thermalization but also effect beyond Bogolyubov theory.
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