Quantum Origin-Manhattan Project in the new century
In the middle of the last century, top scientists such as Einstein, Boll, Oppenheimer, etc. joined the "Manhattan" project led by the United States. Some people may not have heard of the Manhattan Project, but the atomic bombs and computers conceived by the Manhattan Project may be unknown to everyone.
Quantum computing is to combines quantum mechanics and computing technology used in atomic bombs to form more subversive scientific and technological achievements. Coincidentally, the concept of quantum computing was first proposed by Richard Feynman, one of the members of the "Manhattan" project, in 1982.
In 1985, after Feynman proposed the idea of quantum computing, David Duss proposed the quantum Turing machine model. However, after in-depth research, the industry generally believed that there were problems with the practicality of quantum computing, and the quantum algorithms at that time could not be used in general computing. The field has achieved good results, so the subject of quantum computing was once shelved. It was not until 2007, more than 20 years later, that the 16-qubit superconducting quantum computer developed by D-Wave Systems in Canada was successfully released, and people realized that It turns out that quantum computing may not be far away from us.
We know that the nuclear weapons produced by the Manhattan Project have had a huge impact on the security system of the real world, and with the blessing of powerful computing power, quantum computing will also subvert the existing digital world security system. Therefore, the United States will call quantum technology the "Manhattan Project" of the 21st century.
In the traditional computer system, the calculation unit and the computing power are linearly increasing, that is, if I already have 100 CPUs in my computer, adding another CPU at this time will only increase the overall computing power by 1%. Compared with traditional computers, the quantum computing system has added Hadamard Gate, CNOT Gate, and other unit gates that operate quantum into superposition and entangled states, in addition to the three classic logic gates and NOR. Such unique properties double the overall computing power of the quantum computer with each additional computing unit. Quantum hegemony means that quantum computers can solve problems that classical computers cannot solve at all. From the perspective of computational complexity theory, this usually means providing an exponential acceleration beyond the known or possible classical algorithms.
In layman's terms, the increase in computing power of quantum computers is exponential with the increase of computing units, while the increase in computing power of traditional computers increases linearly with the growth of computing units. With the increasing number of computing units, the computing power of quantum computing will be far better than traditional computers at the same cost.
Quantum Superposition-Quantum Algorithm, the Breaker of the Security System
In the current general-purpose computer system, the task of the three basic logic gates of AND or NOT is to complete the addition calculation. All calculation tasks are based on addition. Subtraction is actually adding negative numbers. Conciseness is continuous addition. It is a positive and negative sign for judging the result of subtraction. At present, the main frequency of the main performance index of the computer can also be understood as the number of addition operations that the computer can do in one second. In essence, the current traditional computer algorithm is a method of converting and decomposing a computing task into basic operations such as addition and subtraction, comparison, and jump.
What needs to be pointed out here is that compared with traditional computers, quantum computing does not have any superiority in addition operations. Only by adding logic gates unique to quantum computers such as Hadamard Gate and CNOT Gate into the algorithm can the hegemonic advantage of quantum computing be exerted, and these logic gates are only used for certain specialized tasks. The difficulty of designing quantum algorithms for specific tasks is very high. Therefore, after the quantum computer model was put forward, no one paid attention to quantum computing for a long time. However, with the emergence of the quantum factorization algorithm SHOR, the cold reception period for quantum computing is completely over.
At present, asymmetric key bodies are widely used throughout the Internet. Asymmetric systems can establish a pair of public and private keys, and use the public key to encrypt data. Only the private key corresponding to the public key can decrypt the data. So as to ensure that the data is not leaked and tampered with during data transmission. From the voting signature mechanism on the blockchain to the data transmission of online banking and mobile banking, asymmetric key systems can be described as ubiquitous. The basic starting point of the RSA algorithm, the core foundation of the asymmetric security system, is that it is computationally impossible to factorize the product of large prime numbers. However, the emergence of the SHOR algorithm tells us that this is impossible only in traditional computing models. In the quantum world, everything is possible.
The ingenuity of the SHOR algorithm is that it transforms the factorization problem into a solving period, and the problem of finding a period is transformed into a Fourier transform problem, and finding the Fourier transform is exactly what quantum computing is good at. We know that the Fourier transform is a process of mapping a function from the time domain to the frequency domain, and the frequency is the reciprocal of the period, so the question of the period can be solved by Fourier transform. The Fourier transform can be accelerated by Hadamard Gate, a minimized fast Fourier transform quantum circuit structure.
The reason why the industry attaches great importance to quantum computing is that the basic logic is that the SHOR algorithm can break through the rsa algorithm, and the rsa algorithm is the cornerstone of the entire Internet information security, so mastering quantum computers is equivalent to cracking the entire information security identity authentication system. So as to achieve hegemony. It can be said that if there is no SHOR algorithm, then there is no concept of quantum hegemony.
Quantum entanglement-a long way to go for quantum hegemony
Traditional general-purpose computers are built based on addition operations. Traditional computer designers only need to verify the parity of the calculation results to confirm whether the calculation results are correct. This is also the parity bit mechanism we call daily. This mechanism is very easy to filter out incorrect results to avoid the accumulation of errors.
But the relationship between quantum units is coherent state and superposition state, there is no parity verification relationship in traditional computers at all, and the quantum process is noisy like all other processes. The heat in the qubit or the random fluctuations generated by the quantum process may flip or randomize the state of the qubit, causing the calculation to fail. Therefore, how to perform quantum error correction and ensure the correctness of the results of each step is the key to achieving quantum hegemony.
According to the results of Google’s paper, the fidelity of its quantum computer Sycamore is about 0.2%, and the calculation result required by the SHOR quantum algorithm cannot be lower than 99.3%. Therefore, we can say that there is still a long distance between the strongest quantum computer in the world and cracking the rsa key system.
