Offset-locking-based frequency stabilization of external cavity diode lasers for long-distance quantum communication

TL;DR

This paper demonstrates a method for stabilizing the frequency of external cavity diode lasers using offset-locking, achieving high stability suitable for long-distance quantum communication with quantum memories.

Contribution

The authors developed an offset-locking technique for external cavity diode lasers that achieves frequency stability compatible with quantum memory requirements.

Findings

Achieved frequency stability of 3.6×10^{-12} at 1514 nm

Achieved frequency stability of 3.4×10^{-12} at 1010 nm

Stability is two orders of magnitude better than quantum memory linewidth

Abstract

Quantum repeaters are required for long-distance quantum communication. For efficient coupling of quantum entangled photon sources with narrow-linewidth quantum memories we performed the frequency stabilization of two lasers at 1514 and 1010 nm. The 1514 nm pump laser of the entangled photon source exhibited a frequency stability of 3.6 \times 10^{-12} (\tau = 1 s). The 1010 nm pump laser of the wavelength conversion system exhibited a frequency stability of 3.4 \times 10^{-12} (\tau = 1 s). The stabilities of both lasers were approximately two orders of magnitude smaller than the frequency width of 4 MHz of the Pr:YSO quantum memory. Such frequency-stabilized lasers can realize the remote coupling of a quantum memory and an entangled photon source in quantum repeaters.