Quantum dots can help address the challenges of quantum networks.

 Quantum dots can help address the challenges of quantum networks. 

"Quantum Cryptography with quantum dot-based compact and high-rate single-photon nano-devices. Credit: Lars Luder " (ScitechDaily, Scientists Crack a 40-Year Puzzle in Unbreakable Encryption)

"For decades, scientists thought unbreakable quantum encryption required flawless light sources, a nearly impossible feat. But a team has flipped the script using tiny engineered “quantum dots” and clever new protocols." ScitechDaily, Scientists Crack a 40-Year Puzzle in Unbreakable Encryption)

"By making imperfect light behave more securely, they proved that encrypted messages can travel farther and more safely than ever before. Real-world tests have shown that their method outperforms even the best current systems, bringing practical, affordable quantum-safe communication a significant step closer." (ScitechDaily, Scientists Crack a 40-Year Puzzle in Unbreakable Encryption)

Theoretically, a quantum network is an easy thing to create. The system must only create the quantum channel, or “electromagnetic wormhole” between two objects. And send a photon in that network. The security in a quantum network forms because information is stored in the photon’s particle form. If something touches that photon, this destroys information. Actually, it reorders information in a form that the system cannot use. In a quantum network, a photon is like a ring that is around the superstring. The laser ray will protect that system. 

This thing makes quantum communication ultra-secure. The system can store data in the qubits that are photon or some other particle’s superpositions. It can also send so-called empty photons in the track. This increases the security. But the system should control the entanglements, internal and external superpositions, and data transportation channels. 

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The next part of the text is straight borrowed from ScitechDaily.com

For four decades, the holy grail of quantum key distribution (QKD) — the science of creating unbreakable encryption using quantum mechanics — has hinged on one elusive requirement: perfectly engineered single-photon sources. These are tiny light sources that can emit one particle of light (photon) at a time. But in practice, building such devices with absolute precision has proven extremely difficult and expensive.

To work around that, the field has relied heavily on lasers, which are easier to produce but not ideal. These lasers send faint pulses of light that contain a small, but unpredictable, number of photons — a compromise that limits both security and the distance over which data can be safely transmitted, as a smart eavesdropper can “steal” the information bits that are encoded simultaneously on more than one photon.

Research team flipped the script. Instead of waiting for perfect photon sources, they developed two new protocols that work with what we have now — sub-Poissonian photon sources based on quantum dots, which are tiny semiconductor particles that behave like artificial atoms.

By dynamically engineering the optical behavior of these quantum dots and pairing them with nanoantennas, the team was able to tweak how the photons are emitted. This fine-tuning allowed them to suggest and demonstrate two advanced encryption strategies:

1)A truncated decoy state protocol: A new version of a widely used quantum encryption approach, tailored for imperfect single photon sources, that weeds out potential hacking attempts due to multi-photon events.

2) A heralded purification protocol: A new method that dramatically improves signal security by “filtering” the excess photons in real time, ensuring that only true single photon bits are recorded.

In simulations and lab experiments, these techniques outperformed even the best versions of traditional laser-based QKD methods — extending the distance over which a secure key can be exchanged by more than 3 decibels, a substantial leap in the field.

(ScitechDaily, Scientists Crack a 40-Year Puzzle in Unbreakable Encryption)

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The superstring is like a wire that aims those photons into receivers. The problem is how to make a practical solution for that model. 

The problem with quantum communication is simple. The quantum system used for communication must be fully controlled. The system can use photons to transport information. But the problem is that the photons must be counted. The light source that can send single photons is not very easy to make. This is why researchers use lasers that send an indefinite number of photons. Because the number of photons changes every time the laser sends data, this makes the quantum system difficult to create. If researchers don’t know all parts of the system, they cannot control it. 

The solution to the problem can be quantum dots. In that kind of system. Information travels between superpositioned and entangled photons or other quantum dots. That can be the solution to the problem. How to transmit information in the quantum network. Quantum entanglement is one kind of resonance. In that case, the system transmits oscillations through the quantum fiber from the transmitter to the receiver. This method is not as secure as the photonic-based system. If somebody touches the fiber, it destroys information. 

Another problem is how to send the decryption key in the quantum system. Without that key, the system cannot decrypt data that is stored in the information carriers. Data is stored in the particles’ internal superpositions if it is transported in a quantum channel. This means that the data is transported in a structure that we can call a tower. The tower has floors, which are qubit states. The receiver must know what states are used in the data transportation. 

https://scitechdaily.com/scientists-crack-a-40-year-puzzle-in-unbreakable-encryption/

https://en.wikipedia.org/wiki/Quantum_key_distribution