Quantum optical metrology – the lowdown on high-N00N states

Abstract

Quantum states of light, such as squeezed states or entangled states, can be used to make measurements (metrology), produce images, and sense objects with a precision that far exceeds what is possible classically, and also exceeds what was once thought to be possible quantum mechanically. The primary idea is to exploit quantum effects to beat the shot-noise limit in metrology and the Rayleigh diffraction limit in imaging and sensing. Quantum optical metrology has received a boost in recent years with an influx of ideas from the rapidly evolving field of optical quantum information processing. Both areas of research exploit the creation and manipulation of quantum-entangled states of light. We will review some of the recent theoretical and experimental advances in this exciting new field of quantum optical metrology, focusing on examples that exploit a particular two-mode entangled photon state – the High-N00N state.

Keywords:

• quantum metrology
• quantum imaging
• quantum sensing
• quantum computing

Acknowledgements

Many people have contributed to the work that I cite here, but I particularly would like to acknowledge Pieter Kok and Hwang Lee in our quest to understand high-N00N states and their implications for quantum optical metrology. I would also like to thank Christoph Wildfeuer for giving the manuscript a careful reading and for his many suggestions and corrections. I finally would also like to acknowledge support from the US Army Research Office, the US Intelligence Advanced Research Projects Activity, and the US Defense Advanced Research Projects Agency.