How cosmic rays harm quantum computers

How cosmic rays harm quantum computers

quantum computer That should be the next big milestone in computer technology. They must vastly improve processes for research and companies. Problems that no computer can currently process should be solved in the shortest possible time.

A quantum processor is made up of so called Quantum Bits made up. These qubits can not only tell 1 or 0 accept like regular bits, but also accept superimposition of two states – ie 0 and 1 at the same time, With a whole register of qubits, it becomes possible, in simple words, to perform arithmetic operations with several numbers at the same time.

cosmic rays vs qubits

One of the biggest challenges in building quantum computers is keeping these qubits stable. For this purpose, superconductors are used, for example, with which electron pairs – the so-called Cooper pairs – are generated. Keeping them stable for more than a few 100 microseconds is already a huge effort. Superconductors have to be heavily cooled so that the electron pairs don’t break. Still at -273 degrees, absolute zero.

Study by MIT (nature physics) and from google (nature physics) showed that these electron pairs have a major problem: high energy particles, such as from cosmic or radioactive radiation. They regularly hit the ground and shoot continuously into our bodies. And they also encounter superconductors. Their energy is enough to break the electron pair. MIT was able to determine this in early 2020, and now Google is analyzing the problem in more depth.

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error correction is not enough

“It’s not just one class that’s suffering, the problem is widespread. If it were just localized there wouldn’t be a problem, it would just be an additional error rate to consider. For that you make an error correction. If my All the qubits suddenly go bad, so you can’t fix it anymore,” describes Gerhard Kirchmeyer From the Institute of Quantum Optics and Quantum Information of the Academy of Sciences in Front of Future Zone.

In a test setup by Google, a chip containing 26 qubits Used. In general, the average join max 4 Of these qubits errors in a given time interval. That number increased as they were hit by high-energy particles 24, This poses a serious problem for quantum computers working with superconductors, Kirchmeier says. Because every time high-energy particles break the qubit, the process in a quantum computer has to be stopped and started again.

This is not only tedious, but also counteracts the real idea, namely the high speed. Moreover, such an event does not come once a day, but almost every 10 minutes front. However, computation in a quantum computer often takes several hours.

This is what Google’s quantum computer chip looks like

Discover Shielding Strategies

“It can shut down the whole process,” Kirchmeier explains. But it certainly isn’t fatal to the technology. “Now we have to evaluate which strategies will help shield the particles.” Such a method is, for example, in future data centers giant mountain either deep underground to manufacture. This is probably one of the simplest solutions.

other ideas come from astrophysics, where one wants to make repeated measurements without cosmic radiation continuously interfering with the result. “One can use other materials that dissipate the energy of the particles and thus do not reduce the coherence time of the qubit,” the physicist says. Another option would befall‘ which grab the broken pair of electrons and don’t let them out. They will then not affect the other qubits and the process can continue.

“A combination of these methods would probably be used,” Kirchmair says. The results did not come as a surprise to him. It was already known that cosmic rays and radioactive particles have the ability to disrupt superconductors. However, only the Google study was able to show just how great the effects really are. Now we have to find a solution.


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