Australian physicists have created a new type of qubit - an elementary unit for storing information in a quantum computer. And, in their opinion, we will finally be able to create truly full-scale quantum computers. In a general sense, at the moment there are two capable of creating a quantum computer. In one case, this requires less space, but the systems themselves are incredibly complex to manufacture. In the other, the systems are simpler, but at the same time you have to tear down a couple of walls in order to accommodate such engines in the rooms. The new discovery of scientists in this case may lead to a compromise.
Some researchers use proven methods for capturing a qubit, such as the standard atomic capture model, which uses so-called ion traps and optical (laser) tweezers that can hold particles for a sufficiently long time, which allows analyzing the quantum states of these particles. Others use circuits based on superconducting materials, determining the state of superpositions right inside the hardly perceptible electric fluxes.
The advantage of such systems is that the technologies and equipment necessary for this already exist. This makes these methods relatively accessible and simple at the same time. The main price to pay is in space. And here the technology allows you to create a relatively small number of qubits. Creating and storing hundreds and thousands of qubits inside a single compact computer now seems an impossible task.
Having implemented information coding both in the nucleus and in the electron of the atom, scientists obtained a new silicon qubit, which they called the “trigger qubit”. Its peculiarity is that it can be controlled by electrical signals, instead of magnetic ones. This means that such qubits can maintain quantum entanglement at a distance more distant from each other, which makes scalable computer production easier and cheaper.
“If they are too close or too far apart from each other in a conventional quantum system, the“ entanglement ”between the qubits (what makes quantum computers so special) does not appear,” says Guilherme Tosi, a researcher at the University of New South Wales, who invented new type of qubit.
A trigger qubit will be able to lie between these two extremes, offering true quantum entanglement at a distance of several hundred nanometers. In other words, this may be exactly what will allow the production of scalable quantum computer based on silicon materials.
To clarify: at the moment, scientists have only the scheme of such a device, they have not yet built it. But as Andrea Morell, the head of the research team, says, achieving them is just as important as Bruce Kane's article published in 1998 in Nature, which marked the beginning of the development movement of silicon quantum computing.
“Like Kane’s work, it’s just a theory, a sentence. We haven't built a qubit yet, ”notes Morello.
“We already have some initial experimental data on our hands that indicate the possibility of creating such a system, so now we are engaged in demonstrating this. But basically, our work carries the same visionary view as was the case with the original Kane article. ”
As mentioned above, the trigger qubit works by encoding information inside the electron and the nucleus of the phosphorus atom enclosed within the silicon chip and is connected to a set of electrodes. The entire system is then cooled to near absolute zero and placed inside the magnetic field.
The value of a qubit is determined by a combination of a binary property called spin. If this spin is open to the electron and closed to the nucleus, the qubit acquires the general value of “one”. If we are talking about the reverse order, then the qubit is a “zero”. In this case, the qubit can be controlled using an electric field instead of magnetic signals, which gives two advantages at once. Firstly, it is much easier to integrate such a system into a conventional electronic circuit, and secondly, and more importantly, in this case, qubits are able to interact with each other at more remote distances.
“To control a qubit, you need to place an electron a little further from the nucleus, using electrodes on the chip. By doing this, you also create a dipole, ”says Tosi.
“This is critically important. Since these dipoles can interact with each other at longer distances, up to 1000 nanometers, ”adds Morello.
“This means that qubits on the basis of a single atom can be located much further from each other than previously thought possible. In this case, it becomes possible to integrate more classical components into the system, such as connecting channels, control electrodes and reading devices, at the same time maintaining the exact “atomic” nature of the quantum bit. Production becomes simpler than atomic-level devices, and the technology allows one million cubits to fit in an area of 1 square millimeter. ”
All of this, by and large, means that trigger qubits will keep the balance between compact and potentially accessible quantum computers of the future.
“The design is unique and amazing. And as a lot of conceptual proposals, it makes us wonder why no one had guessed anything like this before, ”Morello says.
The results of the research scientists were published in the journal Nature Communications.
The article is based on materials .
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