物理系学术报告       Physics Department Colloquium

 

1227周五16:00-17:0012-201

 

 

 

Narrow-Band Entangled Photon Pairs: Single Photons under Control

 

Shengwang Du

Department of Physics, The Hong Kong University of Science and Technology

Abstract

Entangled paired photons (biphotons) have become a benchmark tool not only for understanding fundamental quantum physics but also for applications in quantum information science, which requires controlling and manipulating quantum states of the single photons. In this talk, I will review our recently developed narrow-band biphoton generation using spontaneous four-wave mixing in a cold atomic ensemble [1-3]. The long temporal coherence time (100-1000 ns) of these photons allows modulating their quantum waveform in time domain directly [4-6]. These photons can be further hyperentangled in time-frequency, polarization, and space-momentum [7]. For the first time, using modulated single photons, we observed single-photon optical precursors and verified the information speed limit of a single photon [8]. I will also report our recent work on the demonstration of two-photon quantum interference with nondegenerate paired photons [9], the efficient quantum storage of a single photon[10], the coherent control of single-photon absorption and reemission in atomic ensemble [11], and the application in differential-phase-shift quantum key distribution [12]. The works were supported by the Hong Kong Research Grants Council (Project Nos. 600710, 601411, and HKU8/CRF/11G).

 

Brief introduction

Prof. Shengwang Du obtained his BS degree in Electrical Engineering from Nanjing University in 1996, and MS degree in Physics from Peking University in 1999. At the University of Colorado at Boulder, he obtained his MS degree in Electrical Engineering in 2002 and PhD in Physics in 2005. From 2005 to 2008, He had been a Postdoctoral Scholar at Stanford University. Since 2008, Prof. Shengwang Du joined the Department of Physics, the Hong Kong University of Science and Technology.