On-demand storage of photonic qubits at telecom wavelengths

TL;DR

This paper demonstrates the first on-demand storage and retrieval of telecom wavelength photonic qubits using a laser-written waveguide in an erbium-doped crystal, advancing fiber-based quantum networks.

Contribution

It introduces a scalable, fiber-integrated quantum memory for telecom photons with high fidelity and efficiency, not previously achieved at this wavelength.

Findings

Storage fidelity of 98.3% for time-bin qubits

Fiber-to-fiber efficiency of 51%

Compatible with existing fiber networks

Abstract

Quantum memories at telecom wavelengths are crucial for the construction of large-scale quantum networks based on existing fiber networks. On-demand storage of telecom photonic qubits is a fundamental request for such networking applications but yet to be demonstrated. Here we demonstrate the storage and on-demand retrieval of telecom photonic qubits using a laser-written waveguide fabricated in an $^{167}$Er$^{3+}$:Y$_2$SiO$_5$ crystal. Both ends of the waveguide memory are directly connected with fiber arrays with a fiber-to-fiber efficiency of 51%. Storage fidelity of 98.3(1)% can be obtained for time-bin qubits encoded with single-photon-level coherent pulses, which is far beyond the maximal fidelity that can be achieved with a classical measure and prepare strategy. This device features high reliability, easy scalability and can be directly integrated into fiber networks, which could play an essential role in fiber-based quantum networks.