On-chip Time-bin to Path Qubit Encoding Converter via Thin Film Lithium Niobate Photonics Chip

TL;DR

This paper presents an on-chip quantum photonic circuit that efficiently converts time-bin encoded qubits to path-encoded qubits using lithium niobate technology, enabling better integration for quantum networks.

Contribution

It introduces a novel on-chip converter between time-bin and path qubits with high fidelity, demonstrated through experimental validation on a fabricated lithium niobate chip.

Findings

Path qubits with >97% fidelity achieved

Successful demonstration of entanglement distribution

Potential for integration in quantum internet applications

Abstract

The development of quantum internet demands on-chip quantum processor nodes and interconnection between the nodes. Path-encoded photonic qubits are suitable for on-chip quantum information processors, while time-bin encoded ones are good at long-distance communication. It is necessary to develop an on-chip converter between the two encodings to satisfy the needs of the quantum internet. In this work, a quantum photonic circuit is proposed to convert time-bin-encoded photonic qubits to path-encoded ones via a thin-film lithium niobate high-speed optical switch and low-loss matched optical delay lines. The performance of the encoding converter is demonstrated by the experiment of time-bin to path encoding conversion on the fabricated sample chip. The converted path qubits have an average fidelity higher than 97%. The potential of the encoding converter on applications in quantum networks is demonstrated by the experiments of entanglement distribution and quantum key distribution. The results show that the on-chip encoding converter can serve as a foundational component in the future quantum internet, bridging the gap between quantum information transmission and on-chip processing based on photons.