Google released 72-bit quantum computers. Will bitcoin be safe?

Google released 72-bit quantum computers. Will bitcoin be safe?

At the annual meeting of the US physics conference held in Los Angeles this year, Google launched the world's first 72-bit quantum computer, Bristlecon, to achieve a low error rate of 1%, it is the same as Google's previous 9-bit quantum computers. This processor not only helps scientists explore quantum simulation, but also applies quantum optimization and quantum machine learning.

Google Related Personnel said:

We are cautious and optimistic that Bristlecone can achieve Quantum hegemony (Quantum Supremacy ).

Google's latest quantum processor Bristlecon

We can understand the following concepts about this quantum computer:

Quantum hegemony

"Quantum hegemony" is also known as "quantum superiority", which involves the ability of quantum computers to surpass classical supercomputer in some types of equations. Specifically, the 50-bit quantum computer is better than any other classic computer. Achieving quantum hegemony is truly a quantum computer. However, measuring the performance of a quantum processor to determine whether quantum hegemony has been achieved is also the focus of debate between quantum physicists.

As we all know, the computing power of quantum computers is far greater than that of the most advanced supercomputer. Some experts believe that this is a major step in the development of quantum chips. Quantum is arranged in two-dimensional layout, making the control system more complex. This is closer to the condition required to implement surface encoding, namely the ability to manipulate the quantum in a quantum system to execute useful computation. According to Google's staff, the new processor will not only achieve quantum hegemony, but also Google has developed a benchmark testing tool to determine whether quantum computers have reached the standard of quantum hegemony. This test can apply a random single quantum circuit to a processor and measure the output of a classical simulation.

Bristlecone

This computer, developed by Google Quantum AI lab, is named Bristlecone based on a nine-bit matrix developed by Google researchers, similar to the shape of pine nuts ). The goal of Google's quantum AI lab is to build quantum computers that can be used to solve real-world problems, their research strategy is to explore short-term solutions to systems that are compatible with large-scale, universal, and error-tolerant quantum computers.

Chip structure. Each "X" represents a quantum bit, which is connected to adjacent nearest quantum bit.

To allow the quantum processor to run algorithms other than the classical simulation algorithm, it certainly needs more quantum bit numbers, but it still needs more. The most important thing is that the processor must maintain a low error rate in reading and logical operations such as single-and double-quantum bits.

Quantum bit

Quantum bit is the quantum analog form of digital bit and the smallest unit of information processed by traditional computers. However, the number bit is binary and can only be selected between 0 and 1. However, a quantum bit can exist in a superimposed state (its value can be 0, 1, or another combination ). In theory, 2 ^ N data can be stored simultaneously for N quantum bits. For example, the amount of data that can be stored in 250 quantum bits is 2 ^ 250. This number is more than all the atoms in the known universe. During computing, quantum computers can calculate 2 ^ N mathematical operations at the same time, which is equivalent to repeating 2 ^ N calculations in classical computers. It can be seen that quantum computers can save a lot of time and computing units, so that quantum computers can query databases, break down large prime numbers, or create complex scientific models, which is more efficient and accurate than supercomputer.

Quantum bits

However, creating a large quantum computer is not just as simple as concatenating a bunch of quantum bits. Creating a quantum bit array is a challenging task. Special materials are usually required. Expensive laser settings and/or extreme environmental conditions are required to successfully be created and run properly, it depends on whether the quantum bit is based on ions, spin semiconductors, or Google processors or superconducting circuits.

It should be noted that the quantum bit itself is very sensitive to noise environmental interference, and non-ideal environments may cause problems in the state of the quantum bit, so it is very prone to errors. Creating a powerful quantum bit array with a minimum error rate is one of the greatest obstacles between physicists and powerful quantum computers.

Error Rate

Because the quantum state is very unstable, it is far from enough to have only 50 quantum bits, because the quantum entanglement of quantum bits will go wrong, only a sufficient number of quantum bits and low error rates can realize the true meaning of quantum hegemony.

Install Bristlecone

This 72-bit quantum computer uses a quantum bit matrix (with the previous 9-bit general-purpose quantum computer) it can achieve a read error rate of 1%, a single-quantum bit-gate error rate of 0.1%, and a two-bit-gate error rate of 0.6%. The quantum bitgate (also called the quantum logic) is basic and operates a quantum line with a small number of quantum bits. It is the basis of a quantum line, just like the relationship between a traditional logic gate and a General Digital Line. A common quantum gate performs logical operations on one or two quantum bits to generate a single output.

Quantum computers may crack Bitcoin

Currently, quantum computers are only used in scientific research. But if, as Google's lab says, Bristlecone can achieve quantum hegemony, bitcoin and other virtual currencies based on blockchain technology may be cracked.

According to the principle that the minority in the blockchain follows the majority, once the miner has 51% of the computing power, other miners will not be able to continue to obtain Bitcoin. In the future, with the increase of quantum bit in quantum computers, the asymmetric cryptographic algorithm used by blockchain, that is, the public key cryptographic system, will also be under greater threat.

By using quantum computers, we can reverse-run the process of using the public key to deduce the private key. Each private key can be easily inferred by quantum computers. Foreign media Motherboard believes that a 4000-bit quantum computer can collapse the blockchain. That is to say, the individual or team can solve and verify each transaction by first making and applying such a quantum computer, in the future, all uncirculated cryptocurrencies will be monopolized, and the trust system of cryptocurrencies will be collapsed. For details, see FreeBuf's topic article: from concepts to reality, whether public key encryption is in danger.

Strictly speaking, the advent of quantum computers will threaten all the encryption technologies of the existing system and rewrite the security protection of the entire finance and banking industry.

However, many scientists believe that quantum computers cannot replace classical computers. Because of the computing characteristics of quantum computers, it can only be applied in a small number of fields, while the work scope of classical computers is far beyond that of quantum computers.

However, developers of blockchain technology should also be vigilant. Google, a quantum computer, indicates that there may be huge changes in the blockchain field in the future.

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