Nonlinear oscillators and high fidelity qubit state measurement in circuit quantum electrodynamics

TL;DR

This chapter explores the nonlinear response of the Jaynes-Cummings model in circuit QED, demonstrating how strong excitation tones enable high-fidelity qubit state measurement through nonlinear dynamics.

Contribution

It provides an analysis of the nonlinear quantum and semi-classical dynamics of transmon qubits in circuit QED, highlighting their potential for improved qubit state discrimination.

Findings

Nonlinear response enables qubit state discrimination.

Analysis of on-resonance and off-resonance regimes.

Insights into quantum and semi-classical dynamics.

Abstract

In this book chapter we analyze the high excitation nonlinear response of the Jaynes-Cummings model in quantum optics when the qubit and cavity are strongly coupled. We focus on the parameter ranges appropriate for transmon qubits in the circuit quantum electrodynamics architecture, where the system behaves essentially as a nonlinear quantum oscillator and we analyze the quantum and semi-classical dynamics. One of the central motivations is that under strong excitation tones, the nonlinear response can lead to qubit quantum state discrimination and we present initial results for the cases when the qubit and cavity are on resonance or far off-resonance (dispersive).