It’s been four years since Google announced the superiority of quantum computers over conventional computers, but we still haven’t reached practical examples of this technology.

Quantum computers promise to solve certain problems faster than conventional or classical computers. According to New Scientist, Google introduced the concept of quantum superiority in 2019 by unveiling its quantum computer and performing calculations impossible for classical computers.

However, writing the next chapter of the quantum revolution is facing difficulties. Since the controversial Google news in 2019, other groups have made similar claims, but in each instance improved algorithms from classical computers have managed to overcome or at least pose a threat to quantum devices. Given these fluctuations, can we say that quantum computers will take the lead?

Although it was proven in 2022 that classical computers will not be able to produce the results of quantum computer calculations in a reasonable time frame, researchers have come up with a new algorithm to do it. Achieving quantum supremacy once and for all depends on the number of qubits or quantum bits used, as well as the complexity of their programming known as circuit depth. When a computer achieves a high score in both criteria, its results will be beyond the reach of classical and algorithmic computing.

Eventually, the number of qubits will increase enough that no classical algorithm can surpass it, but it is not clear at what point this will happen, and Google is calculating exactly this point.Google’s initial result shows a task called orbital random sampling, which involves checking the amount of qubits after performing a random operation. Google used 54 superconducting qubits for 20 cycles to perform calculations. These values determine the duration of the random operation.

Increasing complexity

In April this year, Google researchers took a similar step with 70 qubits and 24 cycles. This increase may not seem like much, but it will increase the complexity of the work, and Google hopes that this amount will be enough to widen the gap between quantum and classical computing. Calculations on a 70 qubit machine take 47 years for the best supercomputers in the world.

In the current situation, the above specification is the best representation of quantum superiority; However, it is far from ideal. These computers were accompanied by some noise, so it is difficult to verify that the computer is making the most of its quantum nature and is not vulnerable to the advances of the classical computer. Google researchers are working to prove the performance of quantum tasks and the effect of noise on measurements.

Until today, scientists used classical computers to predict the outputs of the quantum machine and then calculate the difference between the final answers. The greater the difference, the more complex the quantum system would be; But it was not clear how much the above scale is faithful to the true nature of the quantum computer, and at what point the noise makes the measurement pointless.

Researchers at the University of Science and Technology of China (USTC) also demonstrated quantum superiority using a 56-qubit superconducting quantum computer called Zuchongzhi, which has the same hardware as Google’s quantum computer, but they are also working on a different design of quantum computing. are using photons for qubits. The machine, called Jiuzhang, has proven quantum advantage but has unique challenges.

The USTC claims that Jiuzhang’s original result would take ordinary computers 600 million years, but in 2022 a group of researchers showed that they could perform the calculations in just a few months on ordinary computers. In April, the USTC solved the problem with a new type of photon detector, again claiming a quantum advantage, but not providing a coherent way to prove it.

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