Decoherence due to nodal quasiparticles in d-wave qubits

TL;DR

This paper analyzes how nodal quasiparticles cause decoherence in d-wave superconductor qubits, proposing a method to estimate decoherence times and identifying conditions for minimal dissipation.

Contribution

It introduces a calculation approach for decoherence due to nodal quasiparticles in d-wave qubits, highlighting the mirror junction's reduced dissipation.

Findings

Decoherence is minimized in mirror junctions due to superohmic dissipation.

Decoherence time depends on tunnel splitting in the double-well potential.

Estimated quality factor based on experimental data.

Abstract

We study the Josephson junction between two d-wave superconductors, which is discussed as an implementation of a qubit. We propose an approach that allows to calculate the decoherence time due to an intrinsic dissipative process: quantum tunneling between the two minima of the double-well potential excites nodal quasiparticles which lead to incoherent damping of quantum oscillations. The decoherence is weakest in the mirror junction, where the contribution of nodal quasiparticles corresponds to the superohmic dissipation and becomes small at small tunnel splitting of the energy level in the double-well potential. For available experimental data, we estimate the quality factor.