Speaker: JyunKai Lin (林俊愷), National Tsing Hua University

Place: Physics Building R019

Title: Generation of Sub-MHz-Linewidth Biphotons in a Two-Level Atomic Ensemble

Abstract:
Realization of long distance quantum communication (LDQC) or linear optical quantum computing (LOQC) requires biphotons with narrow bandwidth and long coherence time, which are typically generated by the spontaneous four-wave mixing based on electromagnetically induced transparency (EIT). However, the narrow bandwidth and generation rate of the EIT-based biphotons strictly rely on high optical depth and multiple laser systems at different transition lines.In this paper, by exploiting moderate OD and a single laser system, we demonstrate sub-natural linewidth biphotons with a high spectral brightness in a two-level atomic ensemble. The sub-natural linewidth biphotons find potential applications in quantum repeaters and large cluster states for scalable LDQC and LOQC, respectively. Generating sub-natural linewidth biphotons in the two-level atomic ensembles also opens up the opportunity to miniaturize the biphoton source for implementing quantum technologies with chip-scale quantum devices.