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For the first time, American scientists from Northwestern University have managed to transfer quantum state of a photon via fiber optic cable over a distance of more than 30 km.
Until recently, this was considered impossible. A demonstration by the researchers took place last year. The ability to quantum state transfer of light particles using the communication infrastructure brings us closer to creating a quantum computing network, innovative encryption methods, and new approaches to scanning.
«It’s incredibly exciting because no one thought it was possible. Our work points the way to next-generation quantum and classical networks that share a unified fiber infrastructure. In essence, it opens the door to taking quantum communications to the next level», — says Prem Kumar, the study’s leader and a computer engineer at Northwestern University.
According to the researchers, this transfer retains quantum properties particle in one place, and carefully destroying it, transfers the preserved properties to a similar particle in another place. Although this process occurs almost instantaneously, quantum entanglement still requires sending a wave of information between points in space.
The quantum state of entangled particles is very unstable. It can disappear the moment after it has appeared. Electromagnetic waves, thermal radiation, friction due to the movement of particles can lead to its destruction if it is not properly protected. Sending a photon through fiber-optic cables, through which a large amount of other information passes, shaking its quantum state, is not the same as shielding of quantum states inside computers.
To protect the photon’s quantum state in the midst of 400 gigabits per second Internet traffic, the researchers used a number of methods to limit the channel of this light particle and reduce the likelihood of its scattering and mixing with other waves.
«We have carefully studied how light scatters and placed our photons at the optimal point where this scattering mechanism is minimal We found that we can carry out quantum communication without interference from classical channels operating at the same time», — explains Prem Kumar.
According to the researcher, such a connection can provide secure quantum communication between different geographically distant nodes. The scientist emphasizes that if the wavelength is chosen correctly, there is no need to create a separate infrastructure, as classical and quantum communications can coexist.
The results of the study are published in the journal Optica
Source: ScienceAlert