Quantum Decoherence of Single-Photon Counters

TL;DR

This paper investigates how quantum features of single-photon counters diminish under environmental noise, demonstrating a transition from quantum to semi-classical measurement regimes and precisely identifying the boundary between them.

Contribution

It provides the first quantitative experimental analysis of quantum decoherence in photon counters, revealing the transition from quantum to classical measurement behavior.

Findings

Quantum features of counters vanish under noise

Transition from quantum to semi-classical regime observed

Explicit boundary between regimes measured experimentally

Abstract

The interaction of a quantum system with the environment leads to the so-called quantum decoherence. Beyond its fundamental significance, the understanding and the possible control of this dynamics in various scenarios is a key element for mastering quantum information processing. Here we report the quantitative probing of what can be called the quantum decoherence of detectors, a process reminiscent of the decoherence of quantum states in the presence of coupling with a reservoir. We demonstrate how the quantum features of two single-photon counters vanish under the influence of a noisy environment. We thereby experimentally witness the transition between the full-quantum operation of the measurement device to the "semi-classical regime", described by a positive Wigner function. The exact border between these two regimes is explicitely determined and measured experimentally.