Do Quantum Computers exist?

Guo Guoping, deputy director of the Key Laboratory of Quantum Information of the Chinese Academy of Sciences believes that quantum is a subject, a science, not metaphysics. It is a description of a certain physical state, so the word quantum does not only appear in quantum mechanics.

Quantum computing is an application in informatics. For example, information is divided into collection, transmission, and processing. Quantum computing is a computing method that uses the principles of quantum mechanics or the characteristics of quantum states to improve information processing capabilities. Use the state of the quantum state to encode, process, and read information. This is quantum computing.

A quantum computer is a machine that can complete quantum computing tasks. Of course, we should not think that quantum computers are just hardware. For our current computers to be able to run, we still need software at various levels. The most intuitive ones are operating systems, application software, and underlying software. Therefore, quantum computers should refer to the general term for software and hardware that can implement quantum computing.

Quantum computing breaks through Moore’s Law. In this regard, Guo Guoping believes that Moore’s Law is a law of economics and describes a development law of integrated circuits. Quantum is not realized by hardware superposition or parallelism, so they are not the same thing. Of course, quantum will also have its own laws.

In his view, the reason why quantum computing is magical, or the reason I think it is a discipline, is due to its physical foundation, that is, the characteristics of quantum states. Take a bit as an example. In quantum, this bit can be in a state where 0 and 1 are superimposed in any ratio, and the phase can also be adjusted. In a bit of classical computing, it can only be at 0 or 1. In quantum, half of the probability of a bit is 0, and the other half of the probability is 1.

This is also the reason why the principle of quantum can be connected with Schrodinger’s cat. The superiority of quantum mechanics and quantum computing lies in the state of quantum superposition. Quantum entanglement is actually the result of the superposition of multi-bit quantum states, and quantum superposition is the fundamental property.

Guo Guoping believes that there is no real quantum computer. In classical computers, most of us talk about physical bits, but real quantum computers are actually logical bits. The difference between logical bits and physical bits is that physical bits have an error rate, such as one in ten thousand, or even one in thousand. Only one or more physical bits can be encoded to form real bits, that is, logical bits.

So from the perspective of this concept, at present, whether it is domestic or foreign, what they are doing basically remains at the stage of physical bits, and of course they are already experimenting with logical bits. Therefore, we say that there is no real quantum computer yet.