The race to lead in quantum computing is not just a matter of two. Currently the United States and China have the upper hand, but other countries, including Germany, France or the United Kingdom, are also making important contributions with a very clear purpose: to acquire a solid technological foundation in this discipline.

In the medium term, quantum computing, if it continues to develop as it has done during the last decade and little by little it circumvents the challenges that still remain to be solved, will make a difference not only in the field of scientific research; also in telecommunications, economy or in the very sensitive field of cryptography, among other critical areas for many nations.

Quantum computing will make a difference not only in the field of scientific research; also in telecommunications, economics or in the very sensitive field of cryptography

The countries that I mentioned in the first paragraph of this article, and some others, have embarked on a long-distance race to avoid being left off the hook, but beyond this international pulse there is a strictly technical struggle that is going relatively unnoticed outside the scientific realm.

The interesting thing is that in this context, the leading role is not played by the countries that seek to lead in quantum computing; It is demanded by the most advanced technologies that are being used to make qubits. However, that in an area where there is so much to do we have several options on the table is great news. Far from being a problem, any innovation that allows us to develop more and better qubits is welcome.

Having quantum computers with many qubits is crucial. And it is so not only because by increasing the number of qubits it is possible to carry out many more calculations simultaneously, but also because in order to make these equipment capable of make amends for their own mistakes it is essential to have more qubits. So many more.

Eagle, the most advanced quantum processor to date, is from IBM and has no less than 127 qubits

The most advanced quantum processor developed to date, known as Eagle, was unveiled by IBM in mid-November, and has 127 qubits. This company plans to have a 433 qubit quantum chip ready by 2022, and one of no less than 1121 qubits in 2023. If this progression is confirmed, come from the hand of IBM or any other company, the first quantum processors with more than a million qubits will arrive in a few years, and just at that moment quantum computers will reach a tipping point.

During the conversation we had with Ignacio Cirac, a Spanish scientist unanimously considered one of the founding fathers of quantum computing, last June he explained to us how many qubits a quantum processor must have to be capable of solve truly significant problems and implement the long-awaited bug fix:

The number of qubits will depend on the type of problems we want to solve with quantum computers. To tackle symbolic problems we will need to have several million qubits. Probably even hundreds of millions of qubits. Right now we are talking about a hundred qubits, so there is a long way to go. There are people who say that 100,000 qubits may solve a specific problem, but it really takes a lot of qubits.

There is no doubt that much remains to be done. Very much. But the researchers are on it. And, furthermore, they are not following a single path. Currently there are two technologies that are proving to have enormous potential not only because of their ability to allow us to increase the number of qubits of quantum processors, but also because they are allowing researchers fine-tune higher quality qubits.

As the quality of a qubit increases, the greater its ability to resist quantum decoherence, which is the phenomenon that appears when the quantum effects that give these computers an insurmountable advantage over classical supercomputers vanish. This is the reason why it is crucial not only to have processors with more qubits, but also to develop higher quality qubits.

Intel is working to increase the scalability of its quantum processors by applying the knowledge that this company has accumulated during decades of producing CMOS devices in their manufacture.

The technology that companies such as IBM, Google or Intel, among others, are using to manufacture their quantum processors uses the superconducting qubits, which are characterized by working at a temperature of about 20 millikelvin, which is approximately -273 degrees Celsius. It is imperative that they operate with the highest degree of isolation from the environment possible and at such an astonishingly low temperature.

IBM aims to have a quantum processor with 1,121 qubits by 2023, and its competitors are likely to be on its heels.

And it is because this minimum level of energy allows them to extend the time during which the quantum states of the system are maintained, and, at the same time, also postpone the moment in which quantum decoherence appears. Quantum states are maintained for a limited period of time, and this time is precisely what we have for carry out quantum logic operations with the qubits of our computer.

One of the greatest successes that superconducting qubits are achieving is precisely how fast they are allowing scaling the number of quantum bits. As weve seen, IBM aims to have a 1,121-qubit quantum processor by 2023, and possibly Intel, Google, and the quantum chips being developed by China will undergo similar development.

In fact, Intel announced just a few days ago that it is working to increase scalability of its quantum processors, applying in their manufacture all the knowledge that this company has accumulated during decades of production of CMOS devices. In fact, the background that both this company and IBM have in the field of semiconductor production works in their favor because all that knowledge is being very useful when it comes to addressing the progressive refinement of their superconducting qubits.

This is the path that IonQ and Honeywell are taking, and they seem to be getting good results. In this article we are not going to delve into the operation of this technology so as not to complicate it too much (we can do it in another report if you are interested in this topic and you confirm it in the comments), but it is interesting that very broadly we can intuit what is your strategy to identify how superconducting qubits differ from those that use ion traps.

Ion trap qubits use positively charged ionized atoms, keeping them confined and isolated in an electromagnetic field

These last use ionized atomsTherefore, they have a non-neutral global electrical charge that allows them to be isolated and confined within an electromagnetic field. This is the starting point of this technology, and from here the strategies used by IonQ and Honeywell, which are the companies that have decided to travel this path with more impetus, to manipulate these ionized atoms and carry out logical operations with them differ. slightly.

The ion-trapped qubits that IonQ and Honeywell are using are more robust than superconducting qubits, allowing them to effectively bypass quantum decoherence for longer.

IonQ acts on the quantum state of its qubits with ion traps by cooling them to reduce the computational noise level and using lasers just below to trade them. But it does not use a single laser; It uses one for each ion, and also a global laser that acts on all of them simultaneously. Honeywell also uses ionized atoms and lasers, but the procedure it uses to establish entanglement between two ions and act on them with a laser is different from that used by IonQ.

In any case, the most interesting thing is that both Honeywell and IonQ ensure that their qubits with ion traps they are more robust than the superconducting qubits used by your competitors. And this means, as we have seen a few lines above, that they manage to preserve the stability of a quantum state for a longer time, which allows them to carry out, according to these companies, more operations with their qubits before quantum decoherence appears. .

Although, as we have seen, superconducting qubits and those using ion traps are currently the most highly developed, they are not the only technologies within our grasp. Many research groups are working in this area, and some promising lines of research propose different ideas at the two in which we just inquired.

There are experts in Spain who work in quantum computing with molecules. They implant ions in macromolecules, store information in them, and can do little calculations. It is a very unique line both in Europe and in the world that could be strengthened. There are many areas where all the greater robustness of ion-trapped qubits versus superconducting qubits. And, incidentally, he told us about another very promising technology, which reminds us that, fortunately, there are several attractive lines of research open that seek to develop more robust and stable qubits:

Superconducting qubits will probably help us to have more qubits, but we think they will have more errors than ion qubits. There is also a third technology, neutral atoms, in which several research groups are working and which is managing to gather more qubits while maintaining the accuracy and lack of errors of the other systems. I hope that very soon we will be able to develop more advanced technologies that will surpass those we have today.

Images | Honeywell | IonQ | Intel

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In the race for the best quantum computer there are two sides, and they are not the United States and China: they are the two most advanced qubit...