Quantum-dot-based cryptography. Brings. Quantum internet. Closer than ever before.

"Cover highlight of the experiment. Single photons emitted by a quantum dot embedded in a photonic device are coupled into a fiber and encoded by ‘Alice’ into three distinct time-bin qubits. After ‘Bob’ performs the decryption, a sequence of quantum keys is shared between the users. Credit: Credit: Light: Science & Applications (2026). DOI: 10.1038/s41377-026-02205-9. Quantum dot–based time-bin QKD achieves stable, long-distance secure communication with practical performance. (ScitechDaily, Quantum Breakthrough: Unhackable Keys Sent Over 120 km Using Quantum Dots)

Researchers transmitted a quantum key over 120 kilometers by using quantum dots. This is a remarkable thing. The unbreakable internet is becoming a reality. In quantum-dot-based systems, the system uses a tool. That is like a pixel camera. The receiving pixel is against the transmitting pixel.

And the transmitting side can be the net of the nano-lasers. In quantum cryptography, the system encodes information into a physical object. In a quantum dot-based transmitter, the transmitter is like a computer screen, but the regular image pixels are replaced with nanolasers. 

When a quantum dot-based system transmits information. It can transmit it. As in the shape of a certain image. The image can be anything. The laser beams transmit that image to the receiver. This is one of the things that the system could do. The system. It can use different radiation frequencies. Like UV, infrared, and visible light. 

Or, even X-rays. The system can use photonic solutions. Their information is stored in a single photon. Optical systems are very hard to break by using eavesdropping. The quantum system could also use coherent radio waves. Or it can use coherent acoustic waves. 

The message can be shared over multiple frequencies. The system can also use spectroscopy as the encryption tool. The system can send an image of the object. But also the spectral image of the elements that form the object. This gives depth to the encryption. The key is the weakest point in the encryption. If the eavesdropper gets the key. That actor can open messages without permission. In quantum dot-based optical encryption. The eavesdropper must cut the laser beam. 

That changes the geometry of the information. And the system detects that thing. The quantum dot-based communication can also use this method. That information. Or. The TCP/IP protocol. Data packages are shared between different communication lines. Then the system sends them. At the same time. Or it can change the data channel all the time. So, when the laser transmits critical information, the other beams can transmit unnecessary data. And the eavesdropper must find the beam that sends important data from meaningless data. 

There is a possibility. Of using the so-called switched order to exchange keys. In that system, the system that normally receives information sends the key. The BizTalk goes like this: Transmitter: “Are you ready”? The receiver: “Yes. Here is the key”. 

In some versions, there is a third party, the encryption system, or keyholder , that shares keys. To the communication system. The BizTalk begins like this: “We (System 1 and System 2) want to talk, and we need the key”. Then, the third party in the system shares the key with those participants. In that case, the third party is the keyholder. That uses different communication lines than the system that shares other information. 

When the system uses quantum encryption, the problem is with the quantum keys. The system must get the quantum key to the receiver. There is a possibility. The system uses pre-installed keys. In this version, the courier transports the USB stick. That involves the key to the receiver. The system can use numbered images as the encryption keys. There are multiple ways to secure the key. 

The system can use a method. The number of images that it uses will be sent from the receiver. The system involves trillions of keys. And then it selects which keys it uses. On a certain day. The selector can be the receiver. There are multiple ways to encode those numbers. One is that the system must send those numbers at a certain time. And it can use a series of marks. There, the opponent picks only remarkable numbers. Those numbers can be replaced by letters. Or some other marks. 

https://scitechdaily.com/quantum-breakthrough-unhackable-keys-sent-over-120-km-using-quantum-dots/