Business collaboration leads to an important milestone in the creation of quantum computing

Quantum Computing: One of the obstacles to progress in the question for a working quantum computer is that the working devices that enter a quantum computer and perform the actual calculations, the qubits, so far produced by universities and in small numbers. But in recent years, pan-European collaboration, in partnership with French microelectronics leader CEA-Leti, has been exploring everyday transistors – present in the billions in the We all have mobile phones – for use as qubits. The French company Leti makes large wafers full of machines, and, after measurement, researchers at the Niels Bohr Institute, University of Copenhagen, have found that these industrial machines are suitable as high a qubit platform capable of moving to the second dimension, an important step for a working quantum computer. The result is now published in Nature Communication.

Quantum dots in a two-dimensional range are a leap forward

One of the key features of the devices is the two-dimensional series of quantum dot. Or more precisely, a series of two or three quantum dots. “What we have shown is that we can achieve single electron control in all of these quantum dots. This is very important for qubit development, because one of the ways you can qubits is So it was very important for us to reach this goal to control the single electrons and to do it in a 2D series of quantum dots “, says Fabio Ansaloni, who was a PhD student, now a post-graduate at a center for Quantum Devices, NBI.

The use of electron spins has been beneficial for the implementation of qubits. In fact, their “silent” nature makes spins weakly interact with the acoustic environment, an important requirement for getting full-performance qubits.

Extending quantum computational processors to the second dimension has been proven to be essential for implementing more efficient quantum error correction methods. Quantum error correction will allow future quantum computers to tolerate individual qubit failures during the computation.

The importance of business scale production

Anasua Chatterjee, Associate Professor at the Center for Quantum Machinery, NBI, said: “The original idea was to make a series of spinning qubits, get down to single electrons and be able to control them and move them around. in that sense it is very good that Leti was able to deliver the samples that we have used, which enabled us to achieve this result.Many credit goes to the pan project consortium -European, and generous EU funding, is helping us to slowly move from a single dot quantum level with one electron to two electrons, and now move on to the two-dimensional heights. is a big goal, because that starts to look like something you need to build a quantum computer, so Leti has been involved in a series of projects over the years, all of which have contributed to as a result of this. “

The credit for getting this far applies to many projects across Europe

The development has been gradual. In 2015, researchers in Grenoble succeeded in making the first qubit spin, but this was based on holes, not electricity. Back then, the performance of the tools made in the “hole regime” was not as good as it could be, and the technology has evolved to make the machines now available at NBI arrays two-dimensional in the single electron regime. The advancement is threefold, the researchers explain: “First, it is necessary to take out the tools in an industrial furnace. The scalability of a modern industrial process is crucial because we start making larger arrays, for example for small quantum simulators Second, when making a quantum computer, you need a series in two dimensions, and you need a way to solve the outside world. connect to each qubit.If you have 4-5 connections per qubit, you will quickly end up with an unreasonable number of wires going out of the low temperature setting.But what is we have shown that we can have one gate for every electron, and you can read and control with the same gate, and finally using these devices we were able to move and exchange single electrons. in a timchea-controlled manner ll on the field, a challenge in itself. “

Two-dimensional arrays can control errors

Controlling errors that appear in the tools is a chapter in itself. The computers we use today make a lot of errors, but they are corrected through something called the repetition code. In a typical computer, you can have information in either 0 or 1. To make sure the calculation result is correct, the computer repeats the calculation and if one transistor makes a mistake, it is corrected through simple majority. . If the majority of the numbers produced in other transistors indicate 1 and not 0, 1 is selected as a result. This is not possible in a quantum computer because you cannot make an exact copy of a qubit, so quantum error correction works in a different way: modern physical qubits do not yet have a low error rate, but there are plenty of them put together in the 2D range, they can track each other, so to speak. This is another advantage of the 2D range that has now been achieved.

The next step from this milestone

The result achieved at the Niels Bohr Institute shows that it is now possible to control single electrons, and perform the experiment without a magnetic field. So the next step is to look for spins – spinning signatures – in the presence of a magnetic field. This will be necessary to implement single and double knots between the single qubits in the field. Theory has shown that a handful of single gates and two gates, called a complete set of quantum gates, is sufficient to enable universal quantum gates.

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