High-rate multiplexed entanglement source based on time-bin qubits for advanced quantum networks

TL;DR

This paper presents a high-rate, multiplexed entanglement source using time-bin qubits, achieving record coincidence rates and high visibilities, advancing quantum network capabilities.

Contribution

The work introduces a 4.09 GHz repetition rate entangled photon source with frequency multiplexing into 8 channels, significantly improving entanglement distribution rates.

Findings

Achieved entanglement visibilities up to 99.4%

Total entanglement rates up to 3.55 million coincidences per second

Predicted potential for tenfold rate improvements

Abstract

Entanglement distribution based on time-bin qubits is an attractive option for emerging quantum networks. We demonstrate a 4.09 GHz repetition rate source of photon pairs entangled across early and late time bins separated by 80 ps. Simultaneous high rates and high visibilities are achieved through frequency multiplexing the spontaneous parametric down conversion output into 8 time-bin entangled pairs. We demonstrate entanglement visibilities as high as 99.4%, total entanglement rates up to 3.55e6 coincidences/s, and predict a straightforward path towards achieving up to an order of magnitude improvement in rates without compromising visibility. Finally, we resolve the density matrices of the entangled states for each multiplexed channel and express distillable entanglement rates in ebit/s, thereby quantifying the tradeoff between visibility and coincidence rates that contributes to useful entanglement distribution. This source is a fundamental building block for high-rate entanglement-based quantum key distribution systems or advanced quantum networks.