Quantum frequency conversion between infrared and ultraviolet

TL;DR

This paper demonstrates quantum frequency conversion from infrared to ultraviolet using a monolithic waveguide, preserving non-classical correlations and enabling UV quantum state generation, with moderate efficiency and noise considerations.

Contribution

First implementation of IR to UV quantum frequency conversion in a waveguide that maintains quantum correlations and functions as a UV quantum light source.

Findings

Conversion efficiency around 5-10%.

Preserves non-classical correlations during upconversion.

Operates as a UV quantum light source.

Abstract

We report on the implementation of quantum frequency conversion (QFC) between infrared (IR) and ultraviolet (UV) wavelengths by using single-stage upconversion in a periodically poled KTP waveguide. Due to the monolithic waveguide design, we manage to transfer a telecommunication band input photon to the wavelength of the ionic dipole transition of Yb${}^{+}$ at 369.5 nm. The external (internal) conversion efficiency is around 5\% (10\%). The high energy pump used in this converter introduces a spontaneous parametric downconversion (SPDC) process, which is a cause for noise in the UV mode. Using this SPDC process, we show that the converter preserves non-classical correlations in the upconversion process, rendering this miniaturized interface a source for quantum states of light in the UV.