סמינר מיוחד בחומר מעובה: Floquet dynamics and time-translation symmetry breaking in nonlinear oscillators

Abstract:

Quantum dynamics of periodically driven systems is described in terms of the Floquet states. The description is based on the fact that a driven system has discrete time-translation symmetry with the period of the driving. Recently much interest have attracted systems where the time symmetry is broken, the “time crystal” effect. Nonlinear oscillators provide an ideal platform for studying this effect. A familiar example is parametric resonance: when a dissipative oscillator is modulated close to twice the eigenfrequency, the period of the parametrically excited vibrations is twice the modulation period. We will show that the symmetry breaking may occur also in the quantum coherent regime. The effect is most pronounced in the semiclassical range. We will discuss the peculiar features of the tunneling of a driven oscillator and how these features can be observed. Time permitting, we will also discuss the scaling behavior close to the critical parameter values where the period-two vibrational states emerge.

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