Komunikacja kwantowa

Quantum communication

One of the biggest threats to our digital world is the vulnerability of electronic communications and security gaps. Hackers are coming up with ways to steal our identities, funds and private data.

Cryptography is a branch of knowledge that deals with securing information from unauthorized access. Cryptography allows us to exchange information over long distances, but still remain secret from unintentional eavesdroppers.

Most modern cryptographic methods rely on well-known mathematical problems such as factorization, which are difficult for classical supercomputers to solve. The possibility of future error- and noise-proof quantum computers requires us to rethink the way we secure our information systems.

In general, quantum communication involves encoding and transmitting messages using different configurations of subatomic particles and their physical parameters. In the full configuration of quantum communication, we transmit qubits instead of classical bits. Current methods of communication of this type use the transmission of photons and their encoded quantum states. This approach and the concept of quantum communication itself enable a completely new approach to the idea of communication, and it is a way to transmit qubits between quantum computing infrastructures, which makes it possible to scale such a computing infrastructure.

The realization of the concept of quantum communication requires, among other things, the development of key methods for efficient generation of pairs of entangled photons, their distribution over longer distances which requires the development of so-called quantum regenerators. A key component of such a regenerator is the so-called quantum memory. Quantum communication offers potentially many new applications, but one of the main and first proposed such applications is the mentioned secure data transmission where using principles studied by quantum mechanics we offer the integrity of the transmitted signal, data and services. One of the proposed such methods is the so-called quantum key distribution.

Quantum key distribution QKD

Quantum Key Distribution (QKD) is a new form of cryptography based on the principles of quantum mechanics and keeps our information completely safe, even from a quantum computer attack.

The main task of QKD is to create a shared secret key between two parties that is perfectly secure. In the simplest version, one party sends qubits in specific quantum states to the other party, who observes or measures them. The person trying to eavesdrop must also measure these qubits, which as we know leaves a detectable trace. This is due to the principles of quantum mechanics, which states that a quantum state cannot be measured without disturbing it.

If the qubits have been disrupted, both parties know to abandon the exchange and remove the key. Otherwise, the parties can use the key to exchange secure communications. It is worth noting that a field of science is also already developing that deals with cryptographic algorithms that are supposed to be resistant to breaking with quantum computers - post-quantum cryptography.

QKD technology is used to secure information transmitted over computer network links over increasingly long distances. As part of the PIONIER scientific network, it was possible to set up and secure a QKD connection over 380 km between Poznan and Warsaw in May 2022.

Post-quantum cryptography

Post-quantum cryptography is a complementary approach to QKD and focuses on developing new classical cryptographic methods based on mathematical problems that are considered difficult to solve even for quantum computers.

Fortunately, in parallel with the development of quantum computers, quantum ciphers (e.g., the Vernam cipher) and cryptographic protocols (e.g., BB-84) are also emerging, whose resistance to various types of attacks is guaranteed by the quantum properties of the particles.