Parity-protected superconducting qubit based on topological insulators

TL;DR

This paper introduces a new parity-protected superconducting qubit architecture using topological Josephson junctions, significantly enhancing coherence times by protecting against charge and flux noise.

Contribution

It presents a novel qubit design based on topological insulators that offers improved noise immunity and coherence times compared to existing superconducting qubits.

Findings

Enhanced $T_1$ and $T_2$ coherence times demonstrated

Protection against both charge and flux noise achieved

Utilizes topological Josephson junctions for fabrication robustness

Abstract

We propose a novel architecture that utilizes two 0-$\pi$ qubits based on topological Josephson junctions to implement a parity-protected superconducting qubit. The topological Josephson junctions provides protection against fabrication variations, which ensures the identical Josephson junctions required to implement the0-$\pi$ qubit. By viewing the even and odd parity ground states of a 0-$\pi$ qubit as spin-$\frac{1}{2}$ states, we construct the logic qubit states using the total parity odd subspace of two 0-$\pi$ qubits. This parity-protected qubit exhibits robustness against charge noise, similar to a singlet-triplet qubit's immunity to global magnetic field fluctuations. Meanwhile, the flux noise cannot directly couple two states with the same total parity and therefore is greatly suppressed. Benefiting from the simultaneous protection from both charge and flux noise, we demonstrate a dramatic enhancement of both $T_1$ and $T_2$ coherence times. Our work presents a new approach to engineer symmetry-protected superconducting qubits.