On-demand generation of multi-photon linear cluster state

Projektinformationen

ODeLiCs

ID Finanzhilfevereinbarung: 101060143

DOI

10.3030/101060143

Projekt abgeschlossen

EK-Unterschriftsdatum 19 Mai 2022

Startdatum 1 Juni 2022

Enddatum 31 Mai 2024

Finanziert unter

• Marie Skłodowska-Curie Actions (MSCA)

Gesamtkosten

Keine Daten

EU-Beitrag

€ 214 934,40

Koordiniert durch

KOBENHAVNS UNIVERSITET
Denmark

Periodic Reporting for period 1 - ODeLiCs (On-demand generation of multi-photon linear cluster state)

Berichtszeitraum: 2022-06-01 bis 2024-05-31

Zusammenfassung vom Kontext und den Gesamtzielen des Projekts

Quantum photonics devices are swiftly evolving toward real-world applications in quantum communication and computation. The general scaling-up strategy involves utilizing small-size entangled states as seeds, which can be fused using probabilistic linear optics gates to form a universal resource for quantum information processing. Traditionally, these entangled states have been generated by probabilistic sources, requiring a massive multiplexing overhead to be scalable. An alternative, resource-efficient strategy involves the deterministic generation of multi-photon entangled seed states using a single quantum emitter. 

Recent experimental work has made significant progress in multi-photon entanglement generation using single atoms. Notably, a 14-photon high-fidelity deterministic entangled source was realized using single atoms. However, solid-state alternatives, like quantum dots, remain attractive due to their high speed, ease of operation, and potential scalability to multiple emitters, which are essential for constructing realistic architectures for scaled up quantum information processing.

Thus, the objective of this project is to successfully develop the first on-demand multi-qubit entanglement source using quantum dots through the implementation of nuclear spin narrowing techniques.

Arbeit, die ab Beginn des Projekts bis zum Ende des durch den Bericht erfassten Berichtszeitraums geleistet wurde, und die wichtigsten bis dahin erzielten Ergebnisse

Previous work with solid-state emitters has been limited to two-qubit entanglement or relied on theoretical assumptions to infer multi-particle entanglement. In this study, we implement high-fidelity spin control on an electron spin in a quantum dot, achieving the first direct demonstration of genuine three-qubit entanglement with a quantum dot source. 

To this end, we enhance the spin dephasing time to approximately 33 ns through nuclear spin narrowing, enabling high-fidelity coherent optical spin rotations. Furthermore, we implement a spin-echo pulse sequence to sequentially generate spin-photon and spin-photon-photon entanglement. The emitted photons are highly indistinguishable, a critical requirement for subsequent photon fusions to create larger entangled states. This study presents a scalable deterministic source of multi-photon entanglement with clear pathways for improvement, promising significant applications in photonic quantum computing and quantum networks.

Fortschritte, die über den aktuellen Stand der Technik hinausgehen und voraussichtliche potenzielle Auswirkungen (einschließlich der bis dato erzielten sozioökonomischen Auswirkungen und weiter gefassten gesellschaftlichen Auswirkungen des Projekts)

The project work showcases a scalable and deterministic source of multi-photon entanglement, with a well-defined route for future enhancements. This development holds significant potential for applications in photonic quantum computing and quantum networks.