Non-Hermitian Dynamics Without Loss Using Superconducting Circuits*

Non-Hermitian systems can exhibit interesting behaviors not seen in Hermitian systems, such as the presence of exceptional points where two (or more) eigenvectors collapse onto each other. Systems that exhibit these points typically involve loss and gain that considerably restricts the amount of quantum coherence. In this talk, following a proposal by Wang and Clerk [1], we describe a closed, four-mode quantum system able to simulate the dynamics of a PT-dimer consisting of two coupled resonators, one with gain and the other with loss, ideally without any actual dissipation that could introduce noise. The four modes are implemented using four harmonics of a superconducting resonator. Arbitrary parametric coupling between the modes is achieved using a SNAIL coupler pumped by microwave drives which gives us wide-ranging control over all parameters. In addition to the physics of the classical PT-dimer, we also expect to observe inter-mode entanglement.

[1] Yu-Xin Wang and A. A. Clerk, “Non-Hermitian dynamics without dissipation in quantum systems”, Phys. Rev. A 99, 063834 (2019)