Efficient gas phase frequency conversion: Nonlinear optics at maximum coherence

Vasily G. Arkhipkin, A. K. Popov

Alexei V. Sokolov, G. Y. Yin, Stephen E. Harris

We describe nonlinear optical processes in a medium with maximal coherence on a Raman transition. The nonlinear polarization of such a medium is of the same order of magnitude as the linear polarization. This allows efficient frequency conversion and generation of a wide spectrum of Raman sidebands. The phase of the coherence can be controlled through a small two-photon detuning from the Raman resonance. An appropriate choice of the phase improves nonlinear generation and propagation of sidebands through an inhomogeneous gaseous medium.

Hao Zhang, Yang Xu, Linshan Sun +3 more

Quantum frequency conversion (QFC) plays a pivotal role in enabling coherent photonic interfaces across disparate quantum systems, serving as a foundation for scalable and interoperable quantum networks. Among various approaches, four-wave mixing (FWM) offers a promising path toward efficient, broadband QFC. In this work, we investigate the feasibility of phase-preserving frequency conversion, a necessary condition for coherent quantum state transfer, by characterizing the spectral phase mapping from input to output fields. We model nonlinear propagation through a gas-filled hollow-core capillary fiber, to demonstrate highly phase-coherent frequency conversion across a broad spectral range, including the infrared to ultraviolet, such as telecom (1550 nm) to visible (516 nm) and deep-UV (308 nm). We further examine how phase-mapping quality and conversion efficiency depend on key system parameters, including the intermediate pulse bandwidth and input pulse energy. Our results reveal optimal operating conditions for achieving future efficient and coherent QFC and provide valuable insights into the nonlinear dynamics underlying FWM-based transduction. These findings lay the groundwork for integrating heterogeneous quantum platforms across widely separated optical bands.

Yu A Il'inskiĭ, Vera M. Petnikova

M. Ducloy

Simon Lefrançois, Alex S. Clark, Benjamin J. Eggleton

We develop a systematic theory for optimizing single-photon frequency conversion using optical Bragg scattering in third-order nonlinear media. The efficiency and phase-matching conditions for the desired Bragg scattering conversion as well as spurious scattering and modulation instability are identified. We find that third-order dispersion can suppress unwanted processes, while dispersion above the fourth order limits the maximum conversion efficiency. We apply the optimization conditions to frequency conversion in highly nonlinear fiber, silicon nitride waveguides, and silicon nanowires. Efficient conversion is confirmed using full numerical simulations. These design rules will assist the development of efficient quantum frequency conversion between multicolor single-photon sources for integration in complex quantum networks.