Superconducting parametric cavity as an analog quantum simulator

Borrowing the concept of analog computers that simulated dynamics of complex classical systems in the era of embryonic digital computers, analog quantum simulators (AQSs) simulate dynamics of complex quantum systems while the emergence of full-scale quantum computer is yet to come. Our AQS is a superconducting quarter-wave coplanar waveguide resonator which is terminated by an asymmetric Superconducting Quantum Interference Device (SQUID). An interaction between two cavity modes can be induced by a microwave pump with a frequency equal to either the sum or difference of two modes. Multiple pumps can be simultaneously applied to the same device, introducing multiple simultaneous couplings. This ability to control mode interactions in multimode device allows us to implement programmable photonic lattices by arranging mode connections in synthetic dimensions. The properties of the simulated model can be revealed through transmission and scattering measurements of the lattice sites. Thus, we successfully simulated the bosonic Creutz ladder [1] and now we demonstrate the simulation of the Su-Schrieffer–Heeger (SSH) model, both of which are paradigmatic topological models. In the SSH lattice, we realize different topological states depending on the intercell-intracell coupling ratio and the parity of the sites in the lattice. We will also present preliminary measurements of injecting nonclassical microwave states into the SSH lattice.

1. Hung et al. PRL, 127, 100503 (2021).