Quantum encrypted communication

Quantum encrypted communication

Quantum secret communication, also known as quantum key distribution, is the only communication method that has been proven to be absolutely secure at the current human cognitive level. It’s function is to dynamically distribute the key between Alice and Bob in real time to ensure the absolute security of communication.

The traditional secure communication is to pre-select and assign the key when Alice and Bob meet, or send a special person to deliver the key. This method is inconvenient and expensive, and is usually used in special scenarios such as communication between the submarine and the base. Quantum key distribution can establish a quantum channel between Alice and Bob, and assign keys in real time according to needs. If attacks or eavesdropping occur during key distribution, both Alice and Bob can detect them.

Quantum key distribution and single photon detection are the key technologies of quantum secure communication. In recent years, major universities and research institutes have carried out a large number of experimental studies on key technologies of quantum communication. Electro-optic modulators and narrow linewidth lasers independently developed by our company have been widely used in quantum key distribution systems. Take continuous variable quantum key distribution as an example, as shown in the following figure.

According to the above principles, the electro-optical modulator (AM, PM) is an important part of the quantum key distribution test system, which has the ability to modulate the amplitude or phase of the optical field, so that the input signal can be transmitted through the optical quantum. The system requires the light intensity modulator to have a high extinction ratio and low insertion loss in order to generate a high extinction ratio pulsed light signal.