Jiaming Li
School of Physics and Astronomy
Sun Yat-sen University
China
Experimental studies of parity-time symmetry breaking transitions with periodically driving
Dissipation is a ubiquitous phenomenon in a real physical system. Its nature could be made understandable by considering the damped oscillation in the classical as well as the quantum regime such as the damped Rabi oscillation of the dissipative two-level system. In this talk, we start from the observation of parity-time (PT)-symmetric transitions in an optically trapped ultracold atom gas [1]. The Floquet PT phase transitions are realized in an ultracold noninteracting 6Li atoms by engineering time-periodic dissipation and coupling. Comparing with a single transition appearing for static dissipation, the time-periodic counterpart undergoes PT-symmetry breaking and restoring transitions at vanishingly small dissipation strength in both single and multiphoton transition domains, revealing rich phase structures associated to a Floquet open system. Then, a pair of coupled active RLC circuits with balanced gain and loss is implemented to map the Floquet PT phase transitions precisely. This classic circuit framework overcomes the fast decay of dissipation and provide a connivance way to measure these PT-phase transitions through the voltage and amplitude of the oscillations. These results enable ultracold atoms as well as active RLC circuit to be a versatile tool for studying novel physical phenomena in PT -symmetric quantum systems.