Drastically suppressing the error of ballistic readout of qubits

TL;DR

This paper investigates the thermal jitter in magnetic flux quanta transmission in Josephson junctions, revealing conditions under which jitter becomes nearly independent of length, which could enhance qubit readout accuracy.

Contribution

It demonstrates that at low damping, the thermal jitter of flux quanta can be drastically suppressed and become length-independent, improving ballistic readout of qubits.

Findings

Jitter scales as √L for large damping and small bias.

At low damping (α=0.03), jitter shows near independence from length.

Suppression of jitter enhances qubit readout fidelity.

Abstract

The thermal jitter of transmission of magnetic flux quanta in long Josephson junctions is studied. While for large-to-critical damping and small values of bias current the physically obvious dependence of the jitter versus length $\sigma\sim\sqrt{L}$ is confirmed, for small damping starting from the experimentally relevant $\alpha=0.03$ and below strong deviation from $\sigma\sim\sqrt{L}$ is observed, up to nearly complete independence of the jitter versus length, which is exciting from fundamental point of view, but also intriguing from the point of view of possible applications.