Nobel Prize, Quantum Entanglement and Cryptocurrency

Quantum Money is a form of money designed based on the principle of quantum mechanics, which makes money that can not be forged. This concept has a certain impact on the development of quantum key distribution.

Quantum money is a form of money. It uses the laws of quantum mechanics to ensure that relevant money cannot be copied, but at the same time, it can be easily validated. These characteristics make it an ideal medium of exchange, just like ordinary cash, without any risk of forgery.

This idea was first proposed by physicist Stephen Wiesner in 1970. The concept used is that any attempt to measure an unknown quantum state will inevitably destroy it. In contrast, the process of measuring a known quantum state retains it. Wiesner realized that if the details of the quantum state are kept secret (for example, kept secret by the central bank), this attribute can be used to ensure the authenticity of the quantum money and ensure that it will never be copied.

Since then, the idea of quantum money has become very influential, forming the basis for many experiments and quantum cryptography technologies, and has become routine: a quantum money protocol must have an effective and preparable money state, effective public authentication, and unforgeability.

Nobel Prize and Quantum Entanglement

Recently, the proudest moment for quantum mechanics was the Nobel Prize in Physics in 2022;

On October 4, 2022, the Royal Swedish Academy of Sciences announced that the 2022 Nobel Prize in Physics would be awarded to French scientist Alain Aspect, American scientist John F. Clauser and Austrian scientist Anton Zeilinger, in recognition of their contributions to "experiments with entangled photons, establishing the violation of Bell inequalities and pioneering quantum information science".

Since the birth of quantum mechanics at the beginning of the last century, it has given birth to such major inventions as transistors and lasers, which is called the first quantum revolution by the scientific community. Recently, the second quantum revolution, represented by quantum computing and quantum communication, is rising again. The Royal Swedish Academy of Sciences said in the Nobel Prize Bulletin that the contributions of the three winners in quantum entanglement experiments this year "have cleared the way for new technology based upon quantum information".

Quantum entanglement has been one of the most controversial issues in quantum mechanics for a long time. Quantum entanglement is a strange quantum mechanical phenomenon. There is a correlation between two quantum states in an entangled state no matter how far apart they are. One of the quantum states changes, and the other state changes instantaneously.

For a long time, some physicists represented by Einstein were skeptical of quantum entanglement, and Einstein called it "spooky action at a distance". They believe that quantum theory is "incomplete", and there is some kind of interaction or information transfer between entangled particles that have not been observed by human beings, that is, "hidden variable".

In the 1960s, the physicist John Stewart Bell proposed the "Bell Inequality" that can be used to verify quantum mechanics. If Bell inequality always holds, then quantum mechanics may be replaced by other theories.

In order to verify Bell inequality, American scientist John Francis Clauser designed relevant experiments, in which special light is used to irradiate calcium atoms, so as to emit entangled photons, and then a filter is used to measure the polarization state of photons. Through a series of measurements, Clauser can prove that the experimental results violate the Bell inequality and are consistent with the predictions of quantum mechanics.

However, this experiment has limitations, including the low efficiency of the experimental device in generating and capturing particles, and the fixed angle of the filter. On this basis, French scientist Alain Aspect designed a new version of the experiment, and the measurement effect is better. Aspect filled an important loophole in the Clauser experiment and provided a very clear result: quantum mechanics is correct, and there is no "hidden variable".

The Austrian scientist Anton Zeilinger later carried out more experiments to verify the Bell inequality. One of the experiments used signals from distant galaxies to control the filter to ensure that the signals would not affect each other, which further confirmed the correctness of quantum mechanics. Zeilinger and his colleagues also demonstrated a phenomenon called quantum teleportation by using quantum entanglement, that is, the quantum state is transferred from one particle to another. His team has also made a lot of research progress in quantum communication.

The official bulletin of the Nobel Prize stated that researchers around the world have found many new methods to use the powerful properties of quantum mechanics, which are all thanks to the contributions of the three winners this year. They swept away the "obstacles" such as Bell inequality and were praised by many well-known media as "clearing the way for new technology based upon quantum information".

Can Quantum Technology Redefine Cryptocurrency?

The characteristics of "quantum entanglement" have become an indispensable basis for global competition in the research and development of quantum technology. Typical is the quantum computer with rapid development of technology. For example, in 2019, Google in the United States solved the problem that it takes 10000 years to use the most sophisticated supercomputer in about 3 minutes.

Although quantum money is called money, it is more like a check in the way of use, because each transaction needs to be verified by the bank. In addition to a unique number printed on each quantum money, there is also an isolated quantum system with two quantum states.

In addition to real money, quantum money is also a feasible direction. However, unlike other common cryptocurrencies (such as Bitcoin), quantum money cannot be backed up according to the principle of non-cloning. A compromise is to use quantum error-correcting codes and store the money in different parts. When a part of the money is damaged, the error can be recovered.

Even if the money fails to pass the bank's inspection, it does not mean that it must be counterfeit money: it may be real money, but its photon deflection surface has been changed due to the influence of the external environment, or it has been measured with a wrong substrate (it may be the person attempting to make counterfeit money, or a broken money detector).

Therefore, the current quantum money formula has a disadvantage: the validation process can only be performed by trusted institutions (such as the central bank), otherwise the details of the quantum state will be kept confidential.

However, the emergence of decentralized currencies such as Bitcoin and Ether has drawn people's attention to the monetary system that does not require centralized control. Therefore, this new research has found a way to create quantum money that can be verified by anyone: it can completely decentralize the quantum money without the need for blockchain to securely record transactions.

The security of this new method comes from post-quantum encryption, and it can resist the attack of quantum computers.

The most promising problem involves the mathematical idea of "lattice", which is a multidimensional lattice formed by a group of vectors. The points in this lattice are connected by vectors of different lengths, and these vectors are easy to calculate. However, it is difficult to find the shortest vector in the lattice, especially when the lattice is random.

One method is to calculate the distance between all points in the random lattice, and finally find the vector with the shortest distance. But as lattices become larger or contain more dimensions, this problem becomes difficult to solve, even for quantum computers.

The method proposed in this study is to encode a random lattice into a quantum property of a quantum monetary unit, which can be an atomic array. Anyone who wants to copy this money must reproduce this random grid. But this can only be done when the shortest vector is known, and even quantum computers can't do this task.

The quantum money state in this experiment is the superposition of states on a Gaussian sphere (mapping the vector of each point on the object's surface to a sphere). This theoretical experiment can ensure the security of funds, and it is easy to be validated because the quantum state of the lattice has specific properties: any user can test it.

Finally, the experimental results of the "Gaussian sphere" will form a physical system that cannot be copied but is easy to check.

"Since our monetary state is physical and tangible, they can be used as tangible but unforgeable notes, but they can also be transferred as digital money through quantum channels." Andrey Khesin of MIT and others said that all this was done by the buyer and the seller without any transaction records: just like ordinary cash today. "Ownership verification can be completed locally and offline, without global synchronization through blockchain and other mechanisms."

However, although the above theory is feasible, we must realize that the technology required to realize quantum money does not exist, let alone enough to be used in the market on a large scale, so its limitations are only discussed theoretically.

Conclusion

Make no decision in case of trouble, quantum mechanics. Perhaps now we should rethink the profound connotation of this sentence.

Now, "quantum entanglement" has been proven to exist for the first time, and has officially stepped onto the stage of world science, which is also the foundation of high-speed computing in the future. It is believed that with the continuous progress in quantum research, more innovation and development space will be brought to future financial risk assessment, blockchain, artificial intelligence (AI), and other industrial utilization.

Let’s look forward to the promising future of quantum technology in the blockchain field.

Author: Gate.io Observer: Byron B. Translator: Joy Z.

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