From adiabatic to dispersive readout of quantum circuits

TL;DR

This paper develops a unified theory for quantum circuit readout that bridges the adiabatic and dispersive regimes, enhancing understanding of spectral properties and measurement techniques in quantum systems.

Contribution

It introduces a comprehensive theoretical framework that connects the adiabatic and dispersive limits, improving the accuracy of quantum circuit spectral analysis.

Findings

Unified theory bridging adiabatic and dispersive regimes

Enhanced understanding of resonance frequency shifts

Applicability to various quantum circuit configurations

Abstract

Spectral properties of a quantum circuit are efficiently read out by monitoring the resonance frequency shift it induces in a microwave resonator coupled to it. When the two systems are strongly detuned, theory attributes the shift to an effective resonator capacitance or inductance that depends on the quantum circuit state. At small detuning, the shift arises from the exchange of virtual photons, as described by the Jaynes-Cummings model. Here we present a theory bridging these two limits and illustrate, with several examples, its necessity for a general description of quantum circuits readout.