Milestones achieved on the path to useful quantum technologies
(a) Operating principle of our approach. Bell pairs are generated sequentially. The detection of one photon triggers the feed-forward including a field programmable gate array (FPGA), which in turn controls the operation mode of an all-optical storage loop. Possible operation modes are “read in and read out” (orange), “Storage” (green), or “PBS interference” (purple) selected by an appropriate switching of the electro-optic modulator (EOM). 2N-fold coincidences confirm the buildup of 2N-photon GHZ states. (b) Sketch of the experimental setup. A Ti:sapphire laser with a wavelength of 775 nm pumps a polarization Bell-state source based on parametric down-conversion in a Sagnac configuration (blue area). One photon of each emitted Bell pair is detected and triggers the feed-forward (red arrows), and the other photon is sent to our all-optical storage loop (green area), where it is stored until it is brought to interference with the subsequent qubit. Credit: Physical Review Letters (2022). DOI: 10.1103/PhysRevLett.129.150501

Albert Einstein said that tiny particles are connected even if they are thousands of kilometers apart. The laws of classical physics don't explain something that is fundamental to quantum physics. The properties of the quantum particles can be linked with each other inanglement.

Nested systems with multiple quantum particles have the potential to be used in data security or quantum computing. The first optical quantum memory is being developed by researchers from Paderborn University. The study was published in a journal.

Light particles areangled.

A group at Paderborn University led by Prof. Christine Silberhorn is using light particles as quantum systems. The researchers want to entangle as many people as possible. They collaborated with researchers from the Institute of Theoretical Physics at Ulm University.

Attempts toentangle more than two particles only resulted in inefficiency. If researchers wanted to link two particles with others, they would have to wait, as the interconnections that promote this entanglement only operate with limited probability. Once the next suitable particle arrived, the photons were no longer a part of the experiment.

Gradually increasing the amount of entangled objects.

Silberhorn says that they have developed a buffer quantum memory that can be switched between different modes.

In the experiment, a small quantum state can be kept until another state is created, and then the two can be entangled. This allows a quantum state to grow particles by particles. The method used by Silberhorn's team is more efficient than any previous experiments. The largest ever photon pairs entangled consisted of twelve individual particles. The creation of this state took more time than expected.

"Our system allows entangled states of increasing size to be gradually built up, which is much more reliable, faster, and more efficient than any previous method." This marks a milestone that puts us in striking distance of practical applications of large, entangled states for quantum technologies. Other scientists will be able to use the method because it can be combined with all common photon-pair sources.

More information: Evan Meyer-Scott et al, Scalable Generation of Multiphoton Entangled States by Active Feed-Forward and Multiplexing, Physical Review Letters (2022). DOI: 10.1103/PhysRevLett.129.150501 Journal information: Physical Review Letters Citation: Achieving greater entanglement: Milestones on the path to useful quantum technologies (2022, October 6) retrieved 6 October 2022 from This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.