Vortex-Meissner phase transition induced by a two-tone-drive-engineered artificial gauge potential in the fermionic ladder constructed by superconducting qubit circuits

Gauge potential is known to account for quite a few fundamental physical issues, such as electromagnetic interaction in electrodynamics, the standard model in particle physics, and even topological phenomena in condensed matter physics. Therefore engineering the so-called artifical gauge potential in controllable experimental platforms has been an attractive topic that may expedite the research on these issues. In this paper, we propose to periodically modulate the frequency of the superconducting flux qubit via two-tone drives, which can be further used to engineer the artificial gauge potential. As an example, we show that the fermionic ladder model penetrated with effective magnetic flux can be constructed by superconducting flux qubits using such two-tone-drive-engineered artificial gauge potential. In this superconducting quantum circuit system, the single-particle ground state can range from vortex phase to the Meissner phase due to the competition between the interleg coupling strength and the effective magnetic flux. We also present the method to experimentally measure the chiral currents by the single-particle Rabi oscillations between adjacent qubits. In contrast to previous methods of generating artificial gauge potential, our proposal does not need the aid of auxiliary couplers and in principle remains valid only if the qubit circuit maintains enough anharmonicity. The fermionic ladder model with effective magnetic flux can also be interpreted as one-dimensional spin-orbit-coupled model, which thus lays a foundation towards the realization of the quantum spin Hall effect.