Working on quantum computing: 'A new way of performing computation'

"Quantum computers have come to change everything. They are a new way of performing computation that is more efficient at its basics," Jan Nogué, a quantum engineer at Barcelona-based Qilimanjaro Quantum Tech, told Catalan News.

Nogué has been working at the 2019-funded company for around two years. He specializes in developing algorithms that can use the company's quantum computers and in finding ways to combine artificial intelligence (AI) with computing.

The company is behind the first quantum computer switched on in Spain built with 100% European technology, located at the Barcelona Supercomputing Center in the Catalan capital. It is a full-stack quantum computing company that develops the hardware and software and designs algorithms for these devices.

"Quantum computers are a different type of computer," Nogué explained, as normal computers use bits to process information, while quantum devices use qubits.

A qubit is the unit of measurement of a quantum computer and can exist in two different states. As opposed to bits that can only be 0 or 1, qubits can be both simultaneously.

"A qubit can be zero and one, with a certain probability of being zero and a certain probability of being one," Nogué explained, something he considers "very mind-blowing." He compares the qubit to Schrödinger's cat, which can be alive and dead at the same time.

These machines have the "potential to deal with problems that a supercomputer or a classical computer cannot solve," he said, which is why he believes everyone "is pushing to have the first one."

Computers like the ones built by Qilimanjaro at the BSC and Abu Dhabi's Technology Innovation Institute are "not good for daily tasks," such as reading emails or surfing the web. A quantum computer is designed to solve very specific tasks that are very hard for classical computers; it is not something people will have at home."

Researchers, such as those at Barcelona Supercomputing Center, are starting to experiment with them. These "are not real computers that a company could put in its headquarters to develop practical things; they are experimental facilities because they have some problems," José María Cela, director of the Computer Applications in Science and Engineering department, told Catalan News.

"The most important problem is that quantum computers are affected by everything, by matter, by radiation, and by particles," he added.

Among the different quantum computers that exist, all those that use the superconducting technology need temperatures near to the absolute zero to work. To work, the chips are stored at the bottom of a structure that fits into a container. This empty container has different temperatures, going from ambient at the top to close to absolute zero at the lowest point. Absolute zero equals 0 kelvin or -273.15ºC.

"You have, on Earth, something that is four times colder than deep space," Nogué said, as these devices are "very sensitive to the environment and everything."

To reach those temperatures, experts combine Helium-3 and Helium-4. The latter is used to inflate balloons and make funny voices. Combining both gases is the only known element that can work at those extreme temperatures without freezing.

Digital and analog

Currently, Barcelona Supercomputing Center is home to a digital quantum computer. There are plans to build a second one, an analog one named MareNostrum-Ona, which, in fact, would be a third, as the one recently inaugurated is a double-quantum computer.

There are some differences between the two quantum computers, the main ones being the errors and the number of qubits required to perform one calculation.

Digital quantum computers "have so many errors that you need a lot of qubits to have a good calculation," Jan Nogué, from Qilimanjaro Quantum Tech, told this media outlet. These computers rely on qubits and gates. Meanwhile, analog computers do not require that many qubits to "run a problem because researchers do not have the kind of errors that are intrinsic to the technology." They use continuous variables to represent and manipulate quantum information.

A digital quantum computer allows researchers to simulate new materials and work on everything related to physics simulation. On the other hand, the analog model is "continuous, so it has more facility to deal with molecules and chemistry," as Nogué explained.

Unlike supercomputers, quantum computers have probabilistic results as qubits can be 0 and 1 simultaneously.

"In the end, you have a distribution of probabilities, what you do is run a lot of shots," Nogué said, as the computer "is intrinsic, and you cannot do any turnovers or any go-arounds, it is what it is," he said.

"The quantum is probabilistic. Nature is like this, so we cannot change it," he said.

Quantum computing is "a promise for the future," José María Cela, from BSC, told Catalan News. "We are researching this, but it's not for today's problems," he said.

Researchers must "execute several times and use statistics to know if the computation is correct or not," Cela added.

Cybersecurity

Quantum computing has come to change the computing industry and, with that, cybersecurity.

BSC has faced several failed cyberattacks since its opening. With quantum computing, everything could completely change as the algorithms used until now could become obsolete.

"When you have a technology, this technology is for everybody, for the good guys, and for the bad guys," José María Cela, director of the CASE department at BSC, told Catalan News when asked about cybersecurity threats.

"If someone has a quantum computer operational in their basement and has not told anyone, this person can read any message that today we are encrypting," Jan Nogué, from Barcelona-based Qilimanjaro Quantum Tech, said when asked about the same issue.

The key to these threats is algorithms. These encrypt all data based "on knowing the prime factors of a number." An example he used was the prime factors of 21, which are seven times three. However, few people may know the prime number of 1,002,000. The quantum computer "does not know it either, and does not know how to calculate it." That basic mathematical operation "is what encrypts everything, but there is an algorithm for a quantum computer that can do this calculation very fast," Nogué added.

Cela considers everyone should be "prepared" and that it is necessary that new "technologies can guarantee that the level of security is not reduced if a criminal group can obtain a quantum computer."

Still, it will take a while for people to be able to know the credit card number of someone else, as to implement an algorithm that could decipher those numbers would need "millions of qubits," Nogué said.

"Quantum computing will have an impact on society. The more optimistic say it will take five to ten years, and the less say it would take between 15 and 30 years," he added.

"Nobody really knows."