Short-time quantum detection: probing quantum fluctuations

TL;DR

This paper investigates how detector clicks relate to the state of a quantum system during short-time interactions, revealing that non-rotating wave effects can cause self-excitations that complicate interpretation.

Contribution

It provides a detailed analysis of short-time quantum detection beyond the rotating wave approximation, highlighting effects like self-excitations in circuit QED.

Findings

Detector clicks correlate with decay only at long times.

Non-rotating wave effects cause self-excitations at short times.

Implications for interpreting quantum measurements in circuit QED.

Abstract

In this work we study the information provided by a detector click on the state of an initially excited two level system. By computing the time evolution of the corresponding conditioned probability beyond the rotating wave approximation, as needed for short time analysis, we show that a click in the detector is related with the decay of the source only for long times of interaction. For short times, non-rotating wave approximation effects, like self-excitations of the detector, forbid a na\"{i}ve interpretation of the detector readings. These effects might appear in circuit QED experiments.