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TT: Fachverband Tiefe Temperaturen

TT 79: Superconductivity: Superconducting Electronics - Circuit QED

TT 79.7: Vortrag

Donnerstag, 15. März 2018, 11:15–11:30, H 2053

Time-Translation Symmetry Breaking and Reentrant First Order Transition in Periodically Driven Quantum Oscillators — •Jennifer Gosner¹, Yaxing Zhang², Mark Dykman³, and Joachim Ankerhold¹ — ¹Institute for Complex Quantum Systems and IQST, Ulm University, Germany — ²Department of Physics, Yale University, USA — ³Department of Physics and Astronomy, Michigan State University, USA

Breaking of discrete time-translation symmetry is a well-known phenomenon in dissipative periodically driven systems. Such systems reveal generic properties, which apply to all multiple-period transitions, but do not occur in period doubling. Here, we investigate a nonlinear oscillator, that is driven at three times the eigenfrequency [1]. Multiple crossings of eigenstates occur with varying parameters of the driving field. Physically, they result from interference of the Floquet wave functions in the classically inaccessible region. We discuss time-translational symmetry breaking, and develop a detailed analysis of the phase-space structure and its symmetries.
In the presence of dissipation, a quantum oscillator can support three states of period-three vibrations that co-exist with the state of no vibrations. With varying detuning a reentrant first-order transition appears, where the populations of these states change exponentially strongly. We study tunneling as well as switching via quantum activation. The results allow revealing "time crystals" in simple quantum systems, including the systems studied in circuit QED.

[1] Y.Zhang et al., PRA 96, 052124 (2017)