Wavelength Conversion of Quantum Dot Photons with Cold-Cs Atoms in a Hollow-Core Fiber*

Solid-state emitters, such as quantum dots, interfaced with cold atomic ensembles can be used to explore novel quantum optics protocols based on single photon nonlinearities. For instance, a quantum state-preserving conversion of photons from one frequency to another can serve as a key networking and information processing element. In this project, we aim to develop an interface between a InAsP quantum dot (QD) embedded in semiconductor nanowire (InP) and laser-cooled Caesium (Cs) atoms confined inside hollow-core fibers. As a precursor framework, we theoretically investigate the conversion of short (~ 1 ns) photon pulses emitted by the quantum dot (894.6 nm) to a S-band telecom wavelength (1469 nm) and a wavelength suitable for satellite-based QKD (794 nm) using four-wave-mixing in the fiber confined Cs cloud. We present analytical and numerical simulation results that specify conditions of the applied laser fields and atom cloud necessary to realize efficient and purity-maintaining wavelength conversion. The platform of laser-cooled atoms in hollow-core fibers helps us in meeting the requirements of applied field powers and high optical depths. 

 

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