Opticians Able to Enhance and Speed Up Quantum Information Processing
Optical quantum gate
Olomouc scientists are capable of increasing by tenfold the efficiency of the device for quantum information processing, during which data is transmitted via photons, or packets of light energy. They use a special quantum gate, which is a circuit for quantum processors.
Experts from the Faculty of Science at Palacký University in Olomouc developed the quantum gate in 2011, and now, four years after, they have found another key function of this device. The designed quantum gate enables them to transform the quantum state of one photon depending on the state of another photon. Its uniqueness among other circuits is ensured by the fact that as the first device of its kind in the world, allowing efficient tuning of the intensity of interaction between two photons.
“This discovery has opened new dimensions in the possibilities of quantum gate utilisation that we have been exploring for several years. Our article demonstrates that our gate can make the circuits for quantum computers much more simple and effective. It can dramatically enhance the efficiency of such devices. The reviewer even spoke of a drastic improvement in the efficiency of quantum computers,” said Karel Lemr from the Joint Laboratory of Optics, who was awarded with the Siemens Prize in 2012 for his research.
The work is a result of several years of research conducted by experts from the Joint Laboratory of Optics – a facility shared by the Regional Centre of Advanced Technologies and Materials at the Faculty of Science at Palacký University and the Institute of Physics of the Czech Academy of Sciences in Prague. The research was also conducted in collaboration with scientists from Adam Mickiewicz University in Poznań. The discovery was published in the prestigious American journal Physical Review Letters.
Tenfold efficacy
According to the scientists, the discovered application is a breakthrough, increasing the efficiency of quantum computation in linear optics. “Our current gate replaces two previous ones. Without our prototype, certain computations could last even a year. With this, however, it can take a few days only, since the efficiency of the whole circuit for quantum computation is increased dramatically – up to ten times. This is the main contribution of our work,” emphasised Lemr.
Experts believe that it will be applied mainly in quantum communication networks. Light is an interesting medium in terms of a “quantum internet”. A photon may be simply emitted via classical optical fibre or empty space.
“Elementary quantum communication networks exist already, but they are still very simple – with one sender and one receiver and without active communication features. They are even commercially available for quantum cryptography, used for example in banks. These systems, however, are not a fully quantum analogy of the Internet,” said Antonín Černoch from the Joint Laboratory of Optics.
Application for a “quantum internet”?
The quantum gate from Olomouc might play a significant role in the active features of quantum communication networks, i.e., components analogous to today’s routers or switches.
“Quantum communication requires junctions where information would be partially processed. In the transmission from light to a solid-matter system, considerable loss and noise would occur. It is better to let light be in charge of the process, as it can be easily operated,” added Černoch.
According to the scientists, quantum information processing and transmission is a safer method and a major step forward in the area of information technologies.
