FerBo: a noise resilient qubit hybridizing Andreev and fluxonium states

TL;DR

FerBo is a superconducting quantum circuit combining Andreev and fluxonium states, designed to be robust against relaxation and dephasing across a broad parameter range.

Contribution

It introduces a hybrid circuit architecture that leverages Andreev and fluxonium states for enhanced noise resilience in quantum computing.

Findings

Protection against relaxation from fermionic-bosonic hybridization

Resilience against dephasing due to wavefunction delocalization

Operates effectively over a wide parameter range

Abstract

We propose a novel superconducting quantum circuit that should be robust against both relaxation and dephasing over a wide and experimentally accessible parameter range. The circuit consists of a parallel arrangement of a large inductance, a small capacitor, and a well-transmitting Josephson weak link. Protection against relaxation arises from the hybridization between the fermionic degree of freedom associated with Andreev levels in the weak link and the bosonic electromagnetic mode of the LC circuit, hence its name: FerBo. Furthermore, as in the fluxonium qubit, delocalization of the wavefunctions in phase space provides resilience against dephasing.