In a cube-shaped glass box with an edge of about 2.7m, a seemingly unspectacular "chandelier" is suspended from the top of the box, causing onlookers to pause.The chandelier is the heart of a quantum computer, and the cube is made of half an inch of borosilicate glass.
The quantum computer is the world's first independent quantum computer, IBM Q System One, which was exhibited at the ces in 2019.
Although many people in the industry questioned the availability of the computer and even thought it was more like a decoration, IBM made it clear that IBM Q System One was an important step in the commercialization of quantum computing.However, shortly after the computer was released, it was reported that the "chandelier" is not as powerful as an ordinary laptop.
Is this assessment objective?When will the long-awaited "quantum hegemony" of quantum computing over classical computers come?
Quantum computer refers to a kind of physical devices that follow the laws of quantum mechanics and perform high-speed mathematical and logical operations and quantum information processing."A device can be defined as a quantum computer when it processes and computes quantum information and runs a quantum algorithm."Guo gang, President of yuweng information technology co LTD, told science daily that the most essential characteristics of quantum computing are quantum superposition and quantum coherence.
As for the characteristics of IBM Q System One, since IBM does not disclose the relevant scientific parameters, it is not possible to analyze its principle and performance."How was this computer built?What about scale and performance?"We can't get information from the news or even tell if it meets the basic criteria of a quantum computer.Han zhengfu, chief scientist of anhui qutian quantum technology co., LTD and professor of the key laboratory of quantum information of the Chinese academy of sciences at the university of science and technology of China, believes that IBM Q System One is at best a model machine, and it is too early to use it to solve practical problems.
At present, leading institutions in the field of quantum computer include Google, IBM, Intel and delft university of technology in the Netherlands.Leading company Google has offered some solutions to the current problems of quantum computers, but has yet to make a real quantum computer.The company's 72 qubit processors, which will be launched in early 2018, cannot be used to model machines or solve practical problems, han told science daily.
As for the claim that "quantum computers are not as powerful as laptops", han zhengfu said that model machines are just like quantum computers in infancy or in the fetus, and there is no comparison with classical computers."When the future popeye is a baby, it makes no sense to compare him with a man in his prime.Likewise, a truly complete quantum computer has yet to emerge, and it is not worth comparing its computational power with that of a classical computer."Said han zhengfu.
There is no doubt that classical computers in their prime are more practical than quantum computers in their infancy.Guo gang also said that compared with the classical computer, the quantum computer's computational power is still difficult to achieve the lead.
As early as in the last century, when the electronic computer was just invented, someone used to compare the abacus with the earliest electronic computer in calculating speed.As a result, electronic computers at that time could not calculate as fast as an abacus.But after years of development, the computing power of electronic computers has changed.Han zhengfu stressed that the classical computer and the quantum computer to compare the principle of advanced, rather than the advantages and disadvantages of the function, otherwise it is not scientific.
Several fundamental problems remain unresolved
In fact, the concept of quantum computing was proposed in the 1980s, and its basic theory was also broken through in the 1990s and early 2000s.But real quantum computers have been slow to arrive.
"Because several fundamental problems have not been solved."Han zhengfu told science and technology daily that the current quantum computer chips are not fidelity enough, the error rate is still relatively high, did not meet the theoretical requirements.
"Even with a quantum computer, we still need it to be able to give us accurate computational structures.Even if its error rate is less than 5 in 10,000, we dare not use it to solve the problem, because we do not fully trust its conclusions."Han zhengfu said.
Quantum coherence is the basis of quantum computing. If there is no quantum coherence, the computation can only be classical.Unfortunately, quantum coherence is quickly destroyed by the environment, so all quantum computing must be done before the decoherence effect occurs and disrupts the quantum bits.This is another threshold that quantum computing has to cross, and physicists are working to keep quantum coherence as long as possible.
Another "high wall" in front of the quantum computer is that its operating conditions are quite harsh.Quantum bits, for example, must operate at close to absolute zero, which requires special and bulky devices to maintain.
In addition, han zhengfu said that the quantum computer's driving circuit, as well as algorithms, software and other aspects also need to be constantly improved, currently does not have the application conditions.
Taking algorithms as an example, quantum computers need the cooperation of algorithms in their work. However, it is not clear what problems existing algorithms, such as Shor algorithm, can solve or cannot solve.For the time being, its availability can only be predicted theoretically and logically.
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