Physicists for the first time demonstrated the process of quantum teleportation from one silicon chip to another. Their system, built on the principles of integral optics, uses a combination of non-linear sources of photons and linear quantum circuits. This design provides one of the highest teleportation accuracies to date. The work is published in Nature Physics.
Scientists often use the principles of integral optics to build systems for processing and transmitting quantum information. Optics have several significant advantages: for example, it allows you to scale the system, increasing its computational abilities. Working with quantum data in integral optics, however, requires several complex mechanisms. Such a system should be able to generate groups of single photons, manage them, and then register them.
In previous works, physicists have already faced the problem of creating a generator with quite bright and distinguishable photons. In addition, combining the source of photons with quantum circuits (registers) within a single compact device is quite a difficult task. Despite this, in 2014, scientists were able to make quantum teleportation of a photon within a single silicon chip.
Now an international team of scientists led by Daniel Llewellyn of the University of Bristol has built a system that allows quantum teleportation from one chip on the other. It consists of two parts – a transmitter (5 x 3 millimetres) and a receiver (3.5 x 1.5 millimetres). The transmitter is a network of non-linear sources of photons and linear quantum circuits.
First, two pairs of photons are generated, which pass through a sensor that determines if they are entangled. Then, through wave channels, they are sent to a linear quantum circuit (a sequence of quantum experiments). The last step is to measure using the Mach-Zehnder interferometer system (this device consists of a waveguide that branches into two parts; electrodes located on the sides of the shoulders of the interferometer are again reduced to a single beam). One of the tangled photons is sent to the receiver on a ten-meter fibre optic cable. The receiver makes the same measurements with the interferometer as the transmitter.
The setup can teleport photons within one and two chips (in the case of two chips, they were at a distance of 10 meters from each other). The degree of coincidence of quantum states (teleportation accuracy) in the first mode is 0.906, in the second – 0.885. In teleportation work in 2014, physicists achieved an indicator of about 0.89.
According to the authors, their work can be useful in larger-scale projects on integrated optics, which are applicable in the field of quantum communication and computing. It is not only a quantum computer but also a quantum network implemented on optical principles. Improving the accuracy of data transfer will give physicists the opportunity to create more efficient means of communication based on quantum teleportation.