Author: Li Ming (harp Technology founder) Editor's Note: This article modifications were made without changing the intent of the author.

After Google ’s high-profile announcement of a successful demonstration of “quantum hegemony”, it once caused fear and fear among bitcoin investors. It is said that it takes 200 seconds to complete a problem that traditional supercomputers can take 10,000 years to solve. The Elliptic Curve Signature Algorithm (ECDSA) used can be easily cracked.

Once an address transfer occurs, the quantum key can be used to find the private key through the public key, and the address's money may be stolen. So some people exclaimed that cryptocurrencies based on cryptography and algorithm-based cryptocurrencies are likely to face a calamity when faced with the exponential growth of computing power. What impact will the advent of quantum computers have on Bitcoin? Can Bitcoin withstand the impact of quantum computer computing power? Opinions diverge.

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So, Bitcoin's encryption algorithm will really be vulnerable to quantum computers, nowhere to hide?

This is how quantum computing is described in the article "Status and Trends in the Development of Quantum Computing Technology" published by Science and Technology Development Research Institute of China, the 9th issue of the China Academy of Science and Technology Development Strategy Research Institute, Vice Chairman of the Chinese People's Political Consultative Conference and Minister of Science and Technology, Wan Gang. : Quantum computing refers to the use of entangled quantum states as information carriers, and the use of the principle of linear superposition of quantum states for parallel computing of information.

The "quantum hegemony" of the quantum computer referred to by everyone is also called "quantum advantage", which means that the quantum computer has a crushing advantage compared to the computer in the traditional sense at present, and a very powerful quantum computer can complete the existing Computer tasks that are almost impossible. For example, Google claims that it takes 200 seconds to complete a problem that traditional supercomputers can take 10,000 years to solve. The impact of the advent of quantum computers on bitcoin. To understand this, we need

Let's spread the knowledge of quantum computers first.

Many people may think of quantum as a microscopic particle. This concept is actually wrong. "Quantum" is the smallest unit of energy currently recognized by humans. The smallest unit of energy is not a continuous process, but a piece by piece, expressed by the concept of quantum. One of the most important features of quantum technology is that traditional computers realize the distinction between 0 and 1 by turning on and off in integrated circuits, and the basic unit is a silicon wafer. Quantum computers also have their own basic unit, qubit.

Kunbit is also called qubit. It expresses 0 or 1 through the quantum two-state quantum mechanics system. For example, the two orthogonal polarization directions of a photon, the spin direction of an electron in a magnetic field or the two directions of a nuclear spin, and the quantum in an atom at two different energy levels, etc. When these states are observed, they will collapse into " 0 "or" 1 ", that is, it has become a certain value, which is the same as the classic quantum theory" Schrödinger's cat ". The principle of quantum computing is the evolution of quantum states in quantum mechanical systems.

## The power of quantum computers

China Academy of Science and Technology Development Strategy pointed out in the article "Status and Trends in the Development of Quantum Computing Technology",

"Quantum computers have extremely high parallel computing capabilities, and can solve certain computational problems that are almost impossible for classical computers, such as large number decomposition, complex path search, etc., to be solved in an acceptable time. Based on quantum computing The development of information processing technology is expected to trigger a new technological revolution, providing unprecedented powerful means for research in many fields such as cryptography, big data and machine learning, artificial intelligence, chemical reaction calculation, material design, and drug synthesis. Science and technology, the economy, finance, and defense security are having a revolutionary impact. "

Quantum computers use the principle of quantum coherent superposition and have super fast parallel computing capabilities. As we all know, the bit length of traditional computers currently reaches 64 bits, and the processor can run 64 bits of data at a time. That is, if 64-bit is used to store a state, how much can it store? 264th power bit. If you use an electronic computer, a bit can only access one state at a time. In other words, it is also an n-bit memory, and the current computer stores only one bit. However, the results stored by quantum computers can reach the power of 2n. Its parallel computing not only far surpasses the latter in terms of storage capacity, but also has fast read speed, and multiple reads and calculations can be performed in parallel at the same time.

For example, a math teacher came up with 100,000 mathematical problems. In the face of the problems, Xiao Ming could only calculate one of them at a time. Suppose he can calculate a problem on average one hour, and it takes 100,000 hours to complete these problems. The quantum computer not only has super fast computing power, but also can run 10,000 questions at the same time in parallel, and can calculate the results of these 10,000 questions in a matter of seconds. It is estimated that if the world's fastest computing power "Tianhe II" supercomputer is used to solve a billion-variable system of equations, it will take 100 years. Using a trillion-quantum computer to solve the same system of equations takes only 0.01 seconds. This is the tremendous power of quantum computers.

## The shortcomings of supercomputing

Since quantum computing was proposed, the experimental process has gone from a single qubit to about ten qubits. Relative to the goal of eventually becoming a practical universal quantum computer, it is still in the exploratory research stage of principle demonstration.

In terms of computing power alone, there is no doubt that the computing power of quantum computers is much higher than today's electronic computers. But in the real world, we the human world can process data into two types. One is interconnected and the other is independent. It is easy to understand the independence of each other. For example, the Xiaoming we mentioned above needs to solve 100,000 problems. Each problem is independent of each other and can be calculated in parallel at the same time. What are the interconnections? Let's take an example: For example, if I want to enter an office in a building, I must first enter through the gate, then take the elevator or climb the stairs, and then I need to come to the company door. After entering the door, To sit down in the office. The entire process, no matter how fast you enter the door or climb the building, but each step cannot be separated from the previous step to deal with in advance.

Computationally, the second step of data processing depends on the completion of the previous step. This correlation is inseparable in processing transactions. Therefore, they cannot be processed in parallel at the same time, but must be completed step by step but must be completed step by step. No matter how fast the calculation is, it must also be processed in series. Therefore, in the face of such things, there is no way for quantum computing to process associated data by improving its concurrency. This provides a feasible solution for cryptography to counter "repetitive" quantum computing. For example, in "Get" Lecture 30 of Drucker Cryptography, the famous science author Drucker mentioned the seventh-generation encryption method against quantum computers-quantum encryption.

For now, the emergence of quantum computers is theoretically a threat to Bitcoin. Because the current hash algorithms and asymmetric encryption algorithms do not have the ability to resist quantum computing, their encryption algorithms can be calculated in parallel. But in the theoretical world, algorithms for anti-quantum computing have been invented, just because the technology of quantum computing has not appeared before, so it has not been applied in practice. From the perspective of gaming, although the quantum computer has been introduced, it is still in the early R & D laboratory stage, and it may take a long time to solve the actual problem.

Technological means such as quantum computers are actively searching for keys to decipher passwords. At the same time, cryptography experts are actively searching for "weapons" against quantum computers. Bitcoin's encryption algorithm will also continue to iterate and upgrade. At that time, you only need to change the Bitcoin blockchain encryption algorithm to an anti-quantum encryption algorithm to combat quantum computing. On the other hand, just as the advent of a nuclear bomb does not mean that the earth must be destroyed, the quantum computer does not have a reasonable and necessary reason to destroy the robustness of Bitcoin.

Bitcoin technology has proven to be very mature and stable over time. A property with both stability and security is a matter worthy of attention and investment.