Fluxon-Based Quantum Simulation in Circuit QED

TL;DR

This paper proposes a fluxon-based quantum simulation platform using circuit QED, enabling the implementation of 1D lattice models and exploring topological phases with potential applications in quantum computing.

Contribution

It introduces a novel fluxon trapping and tunneling method in circuit QED to simulate lattice models and topological phases, including the SSH model.

Findings

Demonstrates fluxon tunneling in a superinductor ring with Josephson junctions.

Shows the realization of the SSH model with fluxons, exhibiting topological edge states.

Proposes using edge states as robust superconducting qubits.

Abstract

Long-lived fluxon excitations can be trapped inside a superinductor ring, which is divided into an array of loops by a periodic sequence of Josephson junctions in the quantum regime, thereby allowing fluxons to tunnel between neighboring sites. By tuning the Josephson couplings, and implicitly the fluxon tunneling probability amplitudes, a wide class of 1D tight-binding lattice models may be implemented and populated with a stable number of fluxons. We illustrate the use of this quantum simulation platform by discussing the Su-Schrieffer-Heeger model in the 1-fluxon subspace, which hosts a symmetry protected topological phase with fractionally charged bound states at the edges. This pair of localized edge states could be used to implement a superconducting qubit increasingly decoupled from decoherence mechanisms.