Phase space topology of a switching current detector

TL;DR

This paper analyzes how the phase space topology influences the speed and accuracy of a Josephson junction-based switching current detector, providing insights for optimizing quantum state readout.

Contribution

It introduces a theoretical and numerical analysis of phase space topology effects on switching dynamics in Josephson junction detectors.

Findings

Optimal circuit parameters avoid unstable limiting cycles

Phase space topology critically affects readout fidelity

Numerical simulations confirm theoretical predictions

Abstract

We examine in theory and by numerical simulation, the dynamic process of switching from a zero voltage to a finite voltage state in a Josephson junction circuit. The theoretical model describes small capacitance Josephson junctions which are overdamped at high frequencies, and can be applied to detection of the quantum state of a qubit circuit. We show that the speed and fidelity of the readout are strongly influenced by the topology of the phase space attractors. The readout will be close to optimal when choosing the circuit parameters so as to avoid having an unstable limiting cycle which separates the two basins of attraction.