Fast-than-light (FTL) communication and travel is the idea that information or matter can move faster than light. However, according to Einstein's special theory of relativity, only photons without rest mass can travel faster than the speed of light.

However, it was assumed that the hypothetical tachyon particle, named by Gerald Feinberg in his 1967 paper entitled "The probability of particles faster than light", moves faster than the speed of light. Still, if it only existed as a phenomenon, it would violate the laws of causality and show that time travel is indeed a possibility – a claim that the scientific community often finds implausible as a theory.

Now that the basic theory underlying the faster-than-light paradox has been presented, the question to ask is: What is quantum entanglement communication and how does it relate to faster-than-light travel theory?

## What exactly is quantum entangled or entangled communication?

In order to fully understand quantum entanglement-based communication, it is first necessary to understand quantum entanglement. Entanglement implies the fact that communication happens instantaneously, and was first proposed by Einstein, Podolsky, and Rosen as "spooky action at a distance" and has its roots in the debate about quantum entanglement and quantum superposition that was first developed in the 1920s and 1930s. Simply put, it occurs when two particles bind together regardless of their actual proximity.

Yet, despite the fact that entangled quantum particles seem to interact instantly regardless of distance and therefore travel at the speed of light, the modern interpretation of quantum mechanics shows that it is impossible to send data using quantum entanglement. A reliable and practical model of quantum entanglement communication is where things get tricky. In order for information to be transmitted or communicated, it must be sent as data, which is not possible with quantum entanglement. However, if it is correct and quantum entanglement communication becomes viable in the future, their use could have a significant impact in areas such as secure information transfer and sensing technology.

In October 2022, El Pais published an interview with French physicist Serge Haroche, who shared the 2012 Nobel Prize in Physics for his work on controlling and capturing individual particles while preserving their quantum character. He was asked what it would mean for quantum communication when Alain Aspect, John F. Clauser, and Anton Zeilinger shared the Nobel Prize in Physics in 2022 for "experiments with entangled photons, demonstrating the violation of Bell inequalities, and pioneering quantum information science." His answer was predictably informative:

“[…] For the past 40 years, fundamental aspects of entanglement have been investigated to show what happens when photons remain bound by an intangible bond known as entanglement, even though they are thousands of kilometers apart. At that time there was no application for this experiment. It took 20 years for experiments like ours to show that isolated quantum systems can be controlled. Today, quantum communication is quite popular and has evolved. People will now think that this can be useful in some way.

The argument is strengthened by the finding that "on a certain continuous-variable basis, photon entanglement regenerates itself as photons move away from their source"; this could be the case for some of the applications mentioned above for securely sending quantum information over long distances.

## What are the Effects of Quantum Communication on Cyber Security?

Quantum technology will undoubtedly have a significant impact on cybersecurity and cryptography. Government agencies around the world are already making plans for “Q-Day,” where quantum computers can use Shor's method to decrypt entire public-key systems based on integer factorization.

Quantum communication is a method that uses the unique properties of these quantum states to provide security, requiring information to be encoded in quantum states known as qubits, unlike the traditional binary system consisting of "zeroes and ones". Photons are typically used for this.

Theoretically sound and future-proof quantum key distribution (QKD) requires reliable nodes over very long distances. Currently, the maximum length of a single QKD link is about 100 km, and the effective point is between 20 and 50 km. Work continues on quantum repeaters and satellite-QKD to increase the range. While the full lifecycle costs are not yet known, the additional costs of hardware integration may be unaffordable.

On the other hand, post-quantum cryptography (PQC) is an additional strategy to deal with future security problems that do not depend on quantum entanglement. PQC security is still controversial and has lattice-based, code-based, hash-based, supersingular isogenes, and multivariate quadratic variants. Algorithms run at the software layer, so this has a long distance advantage.

Other constraints of this strategy include the increasing memory and/or time demands of the software and the still unknown implementation costs such as QKD. However, PQC algorithms have an advantage in this scenario, as the costs of chip-based quantum security technologies are clearly falling and will continue to fall.

Conclusion

As of now, advances in quantum technology and research raise the possibility that one day quantum entanglement-based communications will become a reality, facilitating communications and cybersecurity, and ushering in a whole new era of technology. The best examples of this so far are the 2022 Nobel Prize winners Aspect, Clauser and Zeilinger.

Until then, we'll have to cross our fingers and wait for Feinberg's critical tachyon to appear.

Source: thequantuminsider – James Dargan

📩 21/02/2023 14:20