Introduction to quantum noise, measurement, and amplification

TLDR

Quantum noise has become a central topic as quantum information physics grows, fostering cross‑disciplinary dialogue between condensed‑matter and AMO/quantum‑optics communities. This review provides a pedagogical introduction to quantum noise and its links to quantum measurement and amplification. The authors first present quantum‑noise spectra and detection techniques, then develop weak continuous‑measurement theory and analyze the standard quantum limit for linear amplifiers and position detectors within a general linear‑response framework. They demonstrate that this framework reproduces the Haus–Caves quantum limit for bosonic amplifiers and apply it to electrical circuits, including mesoscopic and resonant‑cavity detectors.

Abstract

The topic of quantum noise has become extremely timely due to the rise of quantum information physics and the resulting interchange of ideas between the condensed matter and AMO/quantum optics communities. This review gives a pedagogical introduction to the physics of quantum noise and its connections to quantum measurement and quantum amplification. After introducing quantum noise spectra and methods for their detection, we describe the basics of weak continuous measurements. Particular attention is given to treating the standard quantum limit on linear amplifiers and position detectors using a general linear-response framework. We show how this approach relates to the standard Haus-Caves quantum limit for a bosonic amplifier known in quantum optics, and illustrate its application for the case of electrical circuits, including mesoscopic detectors and resonant cavity detectors.