What is Quantum Computing?

Quantum computing is a new computing model that regulates quantum information units to perform calculations in accordance with the laws of quantum mechanics. In contrast to traditional general-purpose computers, the theoretical model is a general-purpose Turing machine; general-purpose quantum computers, the theoretical model of which is a general-purpose Turing machine reinterpreted with the laws of quantum mechanics. From the perspective of computable problems, quantum computers can only solve the problems that traditional computers can solve. However, in terms of computational efficiency, due to the superposition of quantum mechanics, some currently known quantum algorithms require faster processing speed. Faster than traditional general-purpose computers.

The quantum mechanical state superposition principle makes the state of the quantum information unit can be in a superimposed state of multiple possibilities, resulting in quantum information processing with greater potential than classical information processing in terms of efficiency. A 2-bit register in an ordinary computer can store only 4 at a time

Proposition of Quantum Computing Concept

The concept of quantum computation was first proposed by P. Benioff of Agang National Laboratory in the early 1980s. He proposed that a two-level quantum system can be used to simulate digital calculations; Feynman also became interested in this issue later. He set about research and gave a lecture at the First Conference on Physics of Computation held at the Massachusetts Institute of Technology in 1981, sketching out the vision of quantum computing. In 1985, D. Deutsch of the University of Oxford proposed the concept of a quantum Turing machine, and quantum computing only began to have the basic form of mathematics. However, the above-mentioned research on quantum computing is mostly confined to the physical nature of computing, staying at a rather abstract level, and not yet entering the stage of developing algorithms.

Mid-term development of quantum computing

In 1994, P. Shor, an applied mathematician at Bell Labs, pointed out [3] that compared to traditional electronic calculators, quantum computing can be used to decompose a large integer into a product of prime factors in a shorter time. This conclusion opens a new stage of quantum computing: the quantum algorithm, which is different from the traditional computing rules, does have its practicality, and it is by no means a trick in the pockets of scientists. Since then, new quantum algorithms have been proposed successively, and one of the important topics facing physicists next is how to build a real quantum calculator to execute these quantum algorithms. Many quantum systems have been named as the basis of quantum calculators, such as photon polarization, cavity quantum electrodynamics (CQED), ion traps, and nuclear magnetic resonance , NMR) and so on. As of 2017, considering the scalability and control accuracy of the system, ion traps and superconducting systems are ahead of other physical systems.

In August 2019, China's quantum computing research made important progress: scientists led the realization of high-performance single-photon sources. Academician of the Chinese Academy of Sciences and Professor of the University of Science and Technology of China Pan Jianwei, led by Lu Chaoyang, Huo Yongheng and others, cooperated with a number of domestic, German, and Danish scholars to propose a new type of theoretical solution for the first time in the world. The single photon source with deterministic polarization, high purity, high isotropy and high efficiency was successfully realized, laying an important scientific foundation for the optical quantum computer to surpass the classical computer. The international authoritative academic journal "Nature · Photonics" recently published the result, evaluating it as "solving a long-standing challenge." ^[1]

The future of quantum computing

Quantum computing will likely make computers more powerful than today's computers, but there are still many obstacles. An important issue in large-scale quantum computing is how to maintain enough quantum coherence of the quantum bits for a long time, and at the same time be able to make enough quantum logic operations with ultra-high precision within this time period.

The world's first commercial quantum computer

Canadian quantum computing company D-Wave officially released the world's first commercial quantum computer "D-Wave One" on May 11, 2011. The slogan of D-Wave is-"Yes, you can have one." D-Wave On uses a 128-qubit (qubit) processor, and the theoretical calculation speed is far faster than any existing supercomputer. But strictly speaking, this is not really a general-purpose quantum computer. It is just a machine that can solve special problems with some quantum mechanical methods. General-purpose tasks are far from being rivals of traditional silicon processors, and programming needs to be relearned. In addition, in order to reduce the qubit energy level as much as possible, it is necessary to generate qubit using niobium in a low-temperature superconducting state, and the operating temperature of D-Wave needs to be maintained near absolute zero (20 mK).

Quantum computing will likely make computers more powerful than today's computers, but there are still many obstacles. One problem with large-scale quantum computing is that it is difficult to improve the accuracy of the required quantum devices.

The world's first commercial quantum computer

Canadian quantum computing company D-Wave officially released the full version on May 11, 2011

D-Wave One quantum processor wafer

The first commercial quantum computer "D-Wave One", the dream of quantum computers is one step closer to us. The slogan of D-Wave is-"Yes, you can have one." In fact, as early as 2007, D-Wave company showed the world's first commercial practical quantum computer "Orion" (Orion), but strictly speaking, the system was not really a quantum computer at the time, but it could be used Some quantum mechanical methods solve problems for special purpose machines.

In January 2017, D-Wave launched the D-Wave 2000Q. They claimed that the system consists of 2000 qubits and can be used to solve optimization, network security, machine learning, and sampling problems. For some benchmark problem tests, such as optimization problems and machine learning-based sampling problems, D-Wave 2000Q outperforms current highly specialized algorithms by 1,000 to 10,000 times. ^[3]

D-Wave One quantum computer system and D-Wave founder and CTO Geordie Rose

University of Science and Technology of China develops non-local quantum simulator for the first time

The research group of Professor Li Chuanfeng from the Key Laboratory of Quantum Information of the University of Science and Technology of China has developed the non-local quantum simulator for the first time and simulated the super-light-speed phenomenon in the parity-time (PT) world.

This experiment fully demonstrates the important role of non-local quantum simulators in the study of quantum physics.

Quantum simulators are specialized quantum computers that solve specific problems. This concept was first proposed by Feynman in 1981. Feynman believes that nature is essentially in accordance with quantum mechanics. Only by using a device that follows quantum mechanics can we better simulate it. This mechanical device is a quantum simulator. At present, in the research of quantum simulators, people pay more attention to its quantum acceleration capability. Generally, the more qubits a quantum simulator controls, the stronger its computing power. ^[4]

Huawei exposes quantum computing results for the first time

On October 12, 2018, Huawei announced the latest progress in the field of quantum computing: the launch of the quantum computing simulator HiQ cloud service platform. The platform includes two parts: the HiQ quantum computing simulator and the HiQ quantum programming framework based on the simulator. This is the company's first step in the fundamental research of quantum computing. ^[5]