This is a huge step for Alice & Bob: The young French company specializing in quantum computers has succeeded in designing the most stable superconducting qubit in the world. This advancement makes it possible to multiply by the lifetime of 100,000 quantum bits and thus constitutes a major advance towards the development of a quantum computer that is likely to have concrete consequences in the real world.
In the process, Alice & Bob raised 27 million euros from several investors to pursue the development of its technology.
Quantum computer, kesako?
The quantum computer mobilizes the possibilities of quantum mechanics to perform calculations that would prove too complex for a conventional computer. A branch of theoretical physics developed in the 1920s by several physicists, including the Germans Max Planck and Werner Heisenberg, quantum mechanics has revolutionized our understanding of physical phenomena on an atomic and subatomic scale.
But as the philosopher of science Etienne Klein reminded us during a USI lecture in 2018, the properties of quantum mechanics today will be ” Resource », Which can be mobilized in the service of IT. ” Quantum physics gives us ways to act, calculate and transfer information using qubits. »
The key is the ability to build potentially super-powerful computers, especially thanks to superposition, a state specific to quantum mechanics that allows particles to exist in several different states at the same time. Thus, unlike a conventional computer bit, a quantum bit or qubit does not have to choose between the values 0 and 1: it can be both at the same time, therefore a greatly increased computing power. David Deutsch, an Oxford physicist and pioneer in quantum computers, argues that a quantum computer can be seen as a wealth of classical computers working together in parallel universes.
Boston Consulting Group (BCG) estimates that the market value created by quantum computers could reach $ 850 billion over the next 30 years.
Solution of quantum instability
Quantum computers, however, have one flaw: the very high error rate that fits into their calculations. They can actually make two types of errors, bit-flips or phase-flips, where a conventional computer can only make one (swap a 0 and a 1).
“ The best quantum machines available at the moment make an average of one mistake every 1,000 operations per year. quantum bit. Under these conditions, after only a few dozen operations, we are already achieving more than noise. If we want to unlock the use cases that are likely to open markets for hundreds of billions of dollars, we need to reduce this error rate by a factor of one million. notes Théau Perronin, General Manager of Alice & Bob.
To circumvent this difficulty, a technique traditionally used by major players in the industry, such as Google and IBM, consists of stacking a large number of qubits to compensate for the margin of error. The problem is that it is not that simple. Qubits must be kept in a quantum state, which involves techniques that may be different (cooling to a cryogenic temperature, capturing them with a laser, etc.), but which have the common point of being very difficult to implement. .
The best current machines therefore have a limited number of qubits: In November last year, IBM designed the very first machine of over 100 qubits with a processor with 127 qubits. We are still far from the thousands of qubits that, according to Théau Perronin, are needed to reconstitute even a single logical qubit, a term denoting a quantum bit that is resistant to error.
Therefore, these machines have no practical use at this time. Admittedly, in December 2019, Google claimed to have achieved quantum supremacy using a 53-qubit machine, the Sycamore processor, which the company claims was used to perform an operation of just over three minutes that would have taken a traditional computer 10,000 years. . But IBM later challenged Google’s claims, saying the classic calculation would take no less than three days. A year later, three researchers, including a Frenchman from the CEA (Commissariat for Atomic Energy and Alternative Energies), supported this idea by developing an algorithm that performed the same calculation in a few hours on a computer.
An error-resistant qubit
Based on this observation, Alice & Bob’s idea is to tackle the problem at the root by designing a new type of qubit, which they have called the superconducting cat qubit, with reference to the famous quantum paradox in Schrödinger’s cat. its box, is both dead and alive. Unlike conventional qubits, the superconducting cat-qubit is naturally resistant to bit-flips: the combination of ten cat-qubits is therefore sufficient to produce a logical qubit.
” In February 2020, we published in Nature Physics a first prototype of a superconducting cat qubit, which already demonstrated a very good level of correction, by a factor of 1,000 compared to a traditional qubit. However, this was still insufficient to completely correct the bit-flip. We announce today that we have further multiplied this correction factor by 100,000, resulting in a qubit capable of resisting bit-flip for two minutes, enough time to perform the calculation. So this problem is completely solved. », Develops Théau Perronin.
” That means we are halfway there. To obtain a logical qubit, we still need to correct the phase-flips errors. For this we will have to accumulate a few dozen superconducting cat qubits. We will then be able to offer the world the very first fully corrected qubit capable of resisting both types of errors. »
The largest fundraiser in the French quantum ecosystem
At the same time, Alice & Bob announced a 27 million euro fundraiser led by Elaia, Bpifrance, through its Digital Venture fund and Supernova Invest. This is the largest fundraising ever in the French quantum computer ecosystem.
“ As deep tech investors, we believe that some of society’s biggest challenges can be solved through cutting-edge technologies created in research laboratories. As such, we regard quantum computers as one of the technologies that will most likely change the world and drive extraordinary advances in a wide range of applications. explains Sofia Dahoune, Investment Director at Elaia, who had already participated in a first fundraising of three million euros carried out by Alice & Bob two years ago.
“ It is rare that we witness such an alignment of the planets, with a high-flying team arriving at the right time in a lively market. We see something very powerful materializing from a technological point of view, which will fundamentally revolutionize computing and thus the economy. »
According to Théau Perronin, this fundraising should serve the goal that the young shooter has set himself to offer a first logical qubit by 2023. With this in mind, it plans to double its workforce and improve the equipment in its laboratory. quantum physics located in Balard, in the 15th arrondissement.
From finance to medicine, countless applications
In the long run, the goal for Alice & Bob, according to its general manager, is to ” build uncompromising, universal, flawless quantum computers and sell their computing power as a service to customers through cloud providers. Beating the best conventional supercomputer on the market today requires 50 logical qubits or a few hundred superconducting cat qubits.
According to Théau Perronin, the perspectives opened up by the quantum computer are particularly fruitful in three areas. Optimization problems, including large amounts of data, firstly with applications in various industries, from the financial sphere, to optimize portfolio management; to energy, for example, to optimize the shape of wind turbine blades. Engineering, then: aircraft design, fluid mechanics, neural networks … Chemistry, and especially materials science, finally, where quantum computation would make it possible to simulate molecules in an accurate way and therefore totally transform certain industries such as electric batteries and medicine.
France quantum champion?
Alice & Bob’s CEO emphasizes that its success is also the result of the academic, technological and financial support of an entire French quantum innovation sector, including CNRS, INRIA, CEA and ENS Paris. France has several start-ups of excellence in quantum technology, including, in addition to Alice & Bob, Pasqal (which has just merged with the Dutch company Qu & Co), Quandela and CryptoNext.
In January 2021, Emmanuel Macron launched an investment plan of 1.8 billion euros over five years around this technology. In early January, the government entrusted GENCI, CEA and INRIA with the task of setting up a national hybrid quantum computer platform with a budget of € 72 million.
Hosted at the Very Large Computing Center in CEA-DAM, it should promote the emergence of an ecosystem around quantum technologies. A co-operation agreement has also been concluded with the Netherlands to develop synergies between the two ecosystems.
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