Storage of telecom-band time-bin qubits in thin-film lithium niobate

TL;DR

This paper demonstrates the first on-chip quantum memory for telecom-band time-bin qubits in thin-film lithium niobate, achieving high fidelity storage and multimode capabilities, advancing integrated quantum information processing.

Contribution

It introduces the first on-chip quantum memory in TFLN doped with erbium ions, with significant improvements in storage time, efficiency, and multimode storage for quantum communication.

Findings

Achieved 400 ns storage time with 1.95% efficiency.

Successfully stored four temporal modes.

Stored time-bin qubits with 96.8% fidelity.

Abstract

Integrated photonics has emerged as a promising platform for quantum communication and quantum computation. Thin-film lithium niobate (TFLN) has gained significant attention in this field due to its exceptional optical properties, enabling the realization of numerous integrated photonic devices. However, quantum memory, which serves as a universal building block for the quantum internet, has not yet been demonstrated in TFLN. In this study, we realized the first on-chip quantum memory using erbium ions doped TFLN. The developed quantum memory achieves a storage time of 400 ns with an efficiency of 1.95%, significantly outperforming conventional waveguide delay lines. The multimode capability is demonstrated by successfully storing four temporal modes. Furthermore, single-photon-level coherent pulses are encoded into time-bin qubits and stored with a fidelity of 96.8% , surpassing the classical limit achievable by measure-and-prepare strategy. Our results demonstrate the first on-chip quantum memory for telecom-band time-bin qubits in TFLN, providing a key building block toward integrated quantum registers and repeaters for scalable quantum information processing.