Propagation of quantum states of light through absorbing and amplifying media (original) (raw)

The role of entanglement in quantum measurement and information processing

2003

The significance of the quantum feature of entanglement between physical systems is investigated in the context of quantum measurements. It is shown that, while there are measurement couplings that leave the object and probe systems nonentangled, no information transfer from object to probe can take place unless there is at least some intermittent period where the two systems are entangled.

Quantum Imaging and Information

2011

Abstract Quantum optics provides a unique avenue to investigate quantum mechanical effects. Typically, it is easier to observe the particle-like behavior of a physical object than it is to observe wave-like behavior. Optics presents us with the reverse case, observing the particle-like behavior of light is difficult. I investigate the utility and limitations of two quantum mechanical effects—weak values and spatial entanglement—in the context of experimental quantum optical communication channels.

Quantum Information and Optics

2002

This is the first of two articles that look at the new field of quantum information and it's relationship with optics. In this article we introduce the central concepts of quantum information, illustrating them with simple optical examples. In the next article we will look at making entangled photons, and some of their recent applications, including tests of nonlocality, quantum cryptography, and quantum computation.

Information and noise in photon entanglement

2000

By using finite resolution measurements it is possible to simultaneously obtain noisy information on two non-commuting polarization components of a single photon. This method can be applied to a pair of entangled photons with polarization statistics that violate Bell's inequalities. The theoretically predicted results show that the non-classical nature of entanglement arises from negative joint probabilities for the non-commuting polarization components. These negative probabilities allow a "disentanglement" of the statistics, providing new insights into the non-classical properties of quantum information.

O ct 2 00 0 Information and noise in photon entanglement

2000

By using finite resolution measurements it is possible to simultaneously obtain noisy information on two noncommuting polarization components of a single photon. This method can be applied to a pair of entangled photons with polarization statistics that violate Bell’s inequalities. The theoretically predicted results show that the non-classical nature of entanglement arises from negative joint probabilities for the non-commuting polarization components. These negative probabilities allow a ”disentanglement” of the statistics, providing new insights into the non-classical properties of quantum information.

Experimental hybrid entanglement between quantum and classical states of light

International Journal of Quantum Information, 2014

The realization of hybrid entanglement between a microscopic (quantum) and a macroscopic (classical) system, in analogy to the situation of the famous Schrödinger's cat paradox, is an important milestone, both from the fundamental perspective and for possible applications in the processing of quantum information. The most straightforward optical implementation of this condition is that of the entanglement between a single-photon and a coherent state. In this work, we describe the first step towards the generation of this type of hybrid entanglement from the experimental perspective.

Quantum information processing and precise optical measurement with entangled-photon pairs

Contemporary Physics, 2003

Two photons in a pair generated in the nonlinear optical process of spontaneous parametric down-conversion are, in general, strongly quantum entangled. Accordingly, they contain extremely strong energy, time, polarization and momentum quantum correlations. This entanglement involves more than one quantum variable and has served as a powerful tool in fundamental studies of quantum theory. It is now playing a large role in the development of novel information processing techniques and new optical measurement technologies. Here we review some of these technologies and their origins.

Increasing Entanglement between Gaussian States by Coherent Photon Subtraction

Physical Review Letters, 2007

We experimentally demonstrate that the entanglement between Gaussian entangled states can be increased by non-Gaussian operations. Coherent subtraction of single photons from Gaussian quadrature-entangled light pulses, created by a nondegenerate parametric amplifier, produces delocalized states with negative Wigner functions and complex structures more entangled than the initial states in terms of negativity. The experimental results are in very good agreement with the theoretical predictions.