Introduction to Quantum Noise Quantum Measurement in Quantum Optics

H. A. Haus

Aashish A. Clerk, Michel Devoret, S. M. Girvin +2 more

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 atomic, molecular, optical--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, the basics of weak continuous measurements are described. Particular attention is given to the treatment of the standard quantum limit on linear amplifiers and position detectors within a general linear-response framework. This approach is shown how it relates to the standard Haus-Caves quantum limit for a bosonic amplifier known in quantum optics and its application to the case of electrical circuits is illustrated, including mesoscopic detectors and resonant cavity detectors.

Hans‐A. Bachor, P. J. Manson

This paper gives an introduction to quantum noise and the limits it places on optical measurements. Squeezed states of light, and their representation on phasor diagrams, are then introduced. The use of squeezed states to improve interferometric measurements is described. Quantum non-demolition measurements are discussed, with particular reference to their use in high sensitivity absorption experiments. Finally, sources of some other types of non-classical light and possible experiments making use of these sources are considered.

Harry J. Kimble, O. Carnal, Zhongliang Hu +4 more

Jianmin Wang, Rong Zhu, Z. Y. Ou

A quantum amplifier usually adds extra noise inevitably through coupling to internal degrees of freedom while amplifying the signal. The introduction of quantum correlations can effectively suppress this extra noise. In this work, we utilize the established quantum correlation between the Stokes field and atomic spin waves in the Raman amplification process to feedback a portion of the Stokes field into the amplifier. This leads to a reduction in quantum noise that is independent of the feedback loss at high gain. A maximum of 6 dB noise reduction is observed. The single-path feedback amplifier is found to be sensitive to the feedback phase, a property that expands its potential for applications in quantum precision measurement, and the general concept can be extended to integrated optics and fiber optic systems.

Paul Busch, Teiko Heinonen, PEKKA J. LAHTI