Measuring the Quantum State of Stored Light

A. K. Chakraborty

Andrew M. C. Dawes, Noah T. Holte, Hunter A. Dassonville

Quantum information can be transferred from a beam of light to a cloud of atoms and controllably released at a later time. These quantum memory devices are fundamental to applications in quantum information science, quantum computing, and quantum communication. We propose a technique for measuring the quantum state of light that has been stored and released from a quantum memory system. This technique does not require careful mode matching can in fact be used to optimize the measured field mode without a priori knowledge of the stored light.

Andrew M. C. Dawes, Noah T. Holte, Hunter A. Dassonville

Slow and stopped light systems form an important piece of the photonics puzzle by acting as memory devices. When used with few-photon light levels, these devices are fundamental to applications in quantum information science, quantum computing, and quantum communication. We report on our progress implementing a technique 1 for measuring the quantum state of light that has been stored in a warm-vapor slow-light system. This technique does not require careful mode matching can in fact be used to optimize the measured eld mode without a prior knowledge of the stored light.

Ulf Leonhardt, Henryk Paul

Daniel Maxwell, D. J. Szwer, David Paredes-Barato +6 more

Kerry B. Burke

Electromagnetically Induced Transparency is an effect that allows light to propagate through an otherwise opaque material. Due to the dispersion properties of the EIT system, it also slows the information carried on the sideband frequencies of a light beam. The effect can also be used to store information in an atomic medium. It was therefore proposed that EIT systems can be applied in optical cicuits, specifically with regard to quantum information processing where it is necessary to delay, or store quantum states of light. Hence it is necessary to understand how EIT systems influence the quantum state of a light beam and whether EIT systems can ever have the potential to delay and store quantum information at the quantum noise limit. ¶ This thesis examines the transfer of an optical signal at the sideband frequencies through an EIT medium. A comprehensive characterisation of an EIT system in terms of delay and signal transmission is performed. This measurement technique provides data on EIT performance over a range of signal frequencies and a range of experimental parameters. Experiments were conducted with both pure Rubidium vapour and Rubidium vapour mixed with a noble gas. ¶ Studies have been made into a new system of measurement that will allow delay, attenuation and added noise spectra to be assessed via a single-shot measurement.