A Thin Film Lithium Niobate Near-Infrared Platform for Multiplexing Quantum Nodes

TL;DR

This paper presents a thin-film lithium niobate integrated photonics platform operating at near-infrared wavelengths, enabling efficient multiplexing of quantum memories and potentially improving entanglement rates in quantum networks.

Contribution

The work introduces a TFLN platform with key components like low-loss couplers, high-extinction switches, and high-bandwidth modulators for quantum memory multiplexing.

Findings

Achieved low-loss couplers (<1 dB/facet)

Demonstrated high-efficiency frequency shifting (>50% at 15 GHz)

Outlined architecture for quantum memory multiplexing with potential 100x entanglement rate improvement

Abstract

Practical quantum networks will require quantum nodes consisting of many memory qubits. This in turn will increase the complexity of the photonic circuits needed to control each qubit and will require strategies to multiplex memories and overcome the inhomogeneous distribution of their transition frequencies. Integrated photonics operating at visible to near-infrared (VNIR) wavelength range, compatible with the transition frequencies of leading quantum memory systems, can provide solutions to these needs. In this work, we realize a VNIR thin-film lithium niobate (TFLN) integrated photonics platform with the key components to meet these requirements. These include low-loss couplers ($<$ 1 dB/facet), switches ($>$ 20 dB extinction), and high-bandwidth electro-optic modulators ($>$ 50 GHz). With these devices we demonstrate high-efficiency and CW-compatible frequency shifting ($>$ 50 $\%$ efficiency at 15 GHz), as well as simultaneous laser amplitude and frequency control through a nested modulator structure. Finally, we highlight an architecture for multiplexing quantum memories using the demonstrated TFLN components, and outline how this platform can enable a 2-order of magnitude improvement in entanglement rates over single memory nodes. Our results demonstrate that TFLN can meet the necessary performance and scalability benchmarks to enable large-scale quantum nodes.