Physics “dressed” quantum light computer in a “straitjacket”

MOSCOW, 18 Jul – RIA Novosti. Physicists from Australia have made the creation of silicon quantum computers closer to reality by creating a special “clothing” for the qubits on the basis of silicon and phosphorus, protecting them from interference, according to an article published in the journal Nature Nanotechnology.

“The main problem of quantum computers is to preserve the entanglement of the qubits for a long enough time that they could spend calculations. In the past we’ve created the longest-lived solid-state qubit, but now has improved this indicator 10 times. “Dressed” the qubit can be controlled in a variety of ways, most of which simply cannot be used for “naked” cousins,” explains Andrea Morello (Morello Andrea) from the University of New South Wales in Sydney (Australia).

Morello and his colleague at the University, Andrew Dzurak for several years to develop the components required to build a full quantum computer. So, in 2010 they created a quantum single-electron transistor, and in 2012 — full silicon qubit on the basis of an atom of phosphorus-31.

In 2013, they assembled a new version of the qubit, which allows almost 100% accuracy to read the data from it and remained stable for a very long time. In October last year, Morello and his team have taken the first step to the creation of the first silicon quantum computer, combining the two qubit in module that performs the logical OR operation.

Australian physicists have managed to significantly improve the performance of such qubits, “wearing” them. Under the “clothing” for the qubits and the other inhabitants of the microworld physics understand the electromagnetic field, which in a special way “glued” to them. In the role of the source of that field, as a rule, are particles of light, photons emitted by a laser in the direction of a qubit with a certain frequency.

The electric field of the photons and the qubit interact in such a way that we, acting on particles of light, can change and read the properties of a qubit, paying attention to how the “split” energy levels of photons interacting with a quantum memory cell.

So, in fact, such a two-level quantum structure called “clothing” in order to “read” or “write” the qubit, we need to interact with the light “wrapping”, but not with the spin of the electron or nuclei, which store quantum information. Similar clothing, as found in physics, protect the qubit from external noise and significantly prolongs his life.

Morello and his colleagues invented a method that allows you to manage the work they have created a solid-state qubit on the basis of phosphorus-31 through such “clothes”, using the pulse microwave laser.

The first experiments with such qubits have shown that “packaging” phosphorus qubit in the luminous “clothing” prolongs his life by 10 times – such qubits, according to scientists, live about 2 to 9 milliseconds, which is enough to conduct a very serious computing. In addition to this, these qubits, according to Australian physicists, it is easier to combine with each other and control.

“For example, our qubit can be monitored simply modulating the frequency of the microwave field, about the same as you tune the FM radio. This can not be done with bare qubits, which are important for the control of the oscillation amplitude, similar to how it works, AM radio. This feature of our qubits, in particular, explains why they are less sensitive to noise, quantum information in them is controlled by the oscillation frequency, which always remains clear, whereas the amplitude may vary under the influence of external processes,” concludes physicist.

So the artist presented himself “dressed” the qubit