Exploring coherent photon-atom interaction at quantum level has become more and more important in modern quantum physics and quantum information science. In this PhD thesis research work, we established two cold ⁸⁵Rb atoms ensemble in 2-dimensional dark-line magneto-optical trap with OD more than 100 and produced long coherence time (~1us) heralded single photons via spontaneous four-wave-mixing process with full temporal waveform control from one of the cold atomic ensemble.

With this system, optical precursor of a single photon was observed for the first time, which verifies that information carried by a single photon cannot be transferred faster than light speed in vacuum even in the quantum world. This closed the longtime debate on the true speed of the information carried by a sin...[ Read more ]

Exploring coherent photon-atom interaction at quantum level has become more and more important in modern quantum physics and quantum information science. In this PhD thesis research work, we established two cold ⁸⁵Rb atoms ensemble in 2-dimensional dark-line magneto-optical trap with OD more than 100 and produced long coherence time (~1us) heralded single photons via spontaneous four-wave-mixing process with full temporal waveform control from one of the cold atomic ensemble.

With this system, optical precursor of a single photon was observed for the first time, which verifies that information carried by a single photon cannot be transferred faster than light speed in vacuum even in the quantum world. This closed the longtime debate on the true speed of the information carried by a single photon.

Single photon reemission timing in a two-level atomic system was the first time been controlled on-demand. With this technique, the quantum timing order of the single photon absorption and reemission was first directly observed in time domain. This technique can also be further used in the field of efficient single atom excitation that is desired for the quantum network.

Finally, a series of work were conducted to improve the quantum optical memory efficiency in cold atomic ensemble. We obtained the highest single-photon storage efficiency of about 50%, which brings the quantum light-matter interface closer to practical quantum information applications. Multi-bin and multi-channel optical memory were also exploited in the following work.