Researchers have managed to quantum entangle four photons in a compact system

The research group of Prof. Hagai Isenberg in collaboration with a French research institute and the doctoral students Daniel Istrata and Yehuda Pilniak from the Hebrew University, published in the journal Nature Communications. , gave rise to new research heralding a new and ground-breaking compact quantum system that allows the entanglement of an arbitrary number of photons

Two quantum particles that share different properties in a special way are able to become entangled. In other words, their properties become common and we cannot treat the two as different substances, even though they may be light years apart. The quantum entanglement turns them into one inseparable system. The particles behave in a coordinated way and change accordingly, so that measurements of their physical properties that change one of them will immediately affect the same property in the other particle. Albert Einstein, who studied the phenomenon, was convinced at the time that the same mysterious connection that exists between interwoven particles regardless of their location - a phenomenon called "quantum non-locality" - proves that quantum mechanics is not a complete theory and called the connection the "action of ghosts".

In a new article published in the prestigious journal Nature Communications. suggests the research group of Prof. Hagai Isenberg The two doctoral students Daniel Istrata and Yehuda Pilniak from the Rakah Institute at the Hebrew University of Jerusalem took part in it., a way to create an important resource in quantum optics and is an entangled state of several photons bundled together, not just two. Creation of a quantum state in which there will be a large number of particles is now scientifically possible A significant breakthrough in quantum technology, which will enable multi-participant quantum communication, advanced quantum computing as well as confirmation of various quantum theories and more. In this context, it is worth noting the words of the British physicist Jim Al-Khalili, who claimed that a quantum computer that manages to maintain entanglement between only 300 atoms will be able to perform certain computational tasks better than a binary computer the size of the entire universe, or that it will be able to perform tasks in a few seconds that a computer Normal will not be enough to perform for a time equal to the entire life span of the universe. Until now, systems that tried to increase the amount of photons in the entangled state required adding many sources of equipment and light detectors in these systems. This need puts a real limit on the practical application of the development of future photon-based systems for quantum processing purposes. The work of Prof. Hagai Isenberg's research group from the Hebrew University changes the picture.

The first time an entangled quantum state of four photons has been successfully created

The current work was done in international collaboration with one of the leading laboratories in the world - that of Prof. Pascal Senlar from the University of Paris Saclay, whose expertise is in the production of high-quality sources capable of emitting photons in a discrete manner, with high quality and at high rates. The researchers were able to assemble a system that successfully demonstrated the creation of entangled quantum states of up to four photons intertwined together. Actually, it is The first time an entangled quantum state of four photons has been successfully created Using one single source capable of proactively emitting photons, while using two light detectors and a single number of optical elements. The results of the research may bring with them promising news to provide a new opportunity for the study of quantum phenomena as well as for its application in technologies based on multi-participant quantum information processing in a simple and portable manner.

A long way in getting the measurements

Doctoral students Daniel Istrata and Yehuda Pilniak, of The research group of Prof. Hagai Isenberg, partners: "Although in theory we expected positive results in the success of the interweaving, it was necessary to go through a long and difficult path in obtaining the measurements that support it. In the initial phase after the system's arrival in France, we were required to characterize the system based on preliminary measurements we made on site. The characterization revealed that we had to calibrate the system in an unconventional way We didn't expect it. However, thanks to the flexibility of the system, we were able to do it on the spot. The first results with the calibrated system and source The calibrated photons unequivocally showed the entanglement of two photons. When this happened, we were very excited and realized that with the system we developed we could go one step further and indeed, we were able to show an entanglement of three and four photons. We were very happy that we were able to achieve this result."

Another important goal achieved by the research is the reduction of the original system in such a way as to allow the her mobility, and therefore will be A significant step towards the practical implementation of future systems of this type. The original system with which the idea of ​​cyclic interweaving was demonstrated, was spread over seven meters in the laboratory. For the first time, the use of the source of the French group allowed for a complete planning of the system, which is mostly entirely based on the use of optical fiber components. The basic idea at the center of the system is the "recycling" of the photons - photons created at a later time will be able to meet photons created earlier. The final result resulted in a significant reduction in the size of the system, to the size of a small desktop computer, thus proving the practical possibilities inherent in the system. This reduction of the system actually made it possible to send it between the countries (from Israel to France), an important and meaningful achievement in itself.

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More of the topic in Hayadan:

• The quantum revolution cannot exist without secure communication
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• Quantum entanglement between events