Monitoring the generation of photonic linear cluster states with partial measurements

TL;DR

This paper presents an efficient scheme for generating and monitoring multi-photon entangled states using a linear optical circuit with a quantum dot source, enabling real-time control for photonic quantum computing.

Contribution

It introduces a resource-efficient method for generating multi-photon entanglement and a real-time monitoring technique using partial measurements in photonic quantum states.

Findings

Successfully generated up to 6-photon entanglement

Achieved real-time entanglement monitoring via partial measurements

Demonstrated scalable entanglement generation rates

Abstract

Quantum states of light with many entangled photons are key resources for photonic quantum computing and quantum communication. In this work, we exploit a highly resource-efficient generation scheme based on a linear optical circuit embedding a fibered delay loop acting as a quantum memory. The single photons are generated with a bright single-photon source based on a semiconductor quantum dot, allowing to perform the entangling scheme up to 6 photons. We demonstrate $2$, $3$, $4$ and $6$-photon entanglement generation at respective rates of $6$kHz, $120$Hz, $2.2$Hz, and $2$mHz, corresponding to an average scaling ratio of $46$. We introduce a method for real-time control of entanglement generation based on partially post-selected measurements. The visibility of such measurements carries faithful information to monitor the entanglement process, an important feature for the practical implementation of photonic measurement-based quantum computation.