
Toshiba Europe has successfully sent messages using quantum key distribution (QKD) across a commercial fibre network, in what the company claims is the first time such complex data has been sent in such a setting using the technique. The trial in Germany, which witnessed the firm send data across a distance of 254km, marks a key validation of QKD over standard telecommunications infrastructure. It also contributes to ongoing efforts to transition quantum communication systems from controlled laboratory conditions into operational environments.
The experiment was carried out using Deutsche Telekom’s fibre network. The system implemented an entanglement-based QKD protocol, which transmits pairs of quantum-correlated photons between endpoints. Any attempt to intercept the quantum key alters the state of the particles and becomes detectable, ensuring a secure exchange of cryptographic keys between parties.
The technology operates by encoding information in the quantum states of photons and transmitting them through fibre optic cables. In the case of this trial, Toshiba achieved the result without the use of cryogenic cooling, which is typically required in quantum systems to preserve coherence. Instead, the system utilised room-temperature components, increasing the feasibility of practical deployment.
Robert Woodward, who leads Toshiba Europe’s QKD research team, confirmed that this was the first time such a distance had been covered using entangled photons on installed fibre without cryogenic infrastructure. “The success of the trial indicates that practical QKD is feasible using standard telecom equipment,” Woodward said.
The results of the trial were published in the scientific journal Nature. The publication confirmed that the system maintained secure key exchange with a low quantum bit error rate (QBER), a critical metric in QKD performance. Toshiba used a twin-field QKD protocol, which enables key exchange between two parties with the measurement point located midway between them, reducing signal loss and allowing longer-distance communication.
Quantum key distribution is viewed as a foundational element for future cybersecurity frameworks. Traditional public key encryption methods rely on computational complexity, which may be vulnerable to decryption by quantum computers. QKD offers a physics-based alternative that is not subject to the same algorithmic limitations.
While Toshiba has not confirmed commercial rollout plans or implementation schedules, the company stated that the successful field test demonstrates the potential for integration into broader telecommunications networks. Various governments and enterprises are evaluating QKD as a component of long-term secure communications planning, particularly as quantum computing capabilities continue to evolve.
Similar quantum communication trials in recent years
Across Europe, several initiatives are advancing QKD integration into live telecom networks. In the UK, BT and KETS Quantum Security tested a chip-based QKD system for deployment in standard network hardware. France’s ParisRegion QCI project, led by Orange, has also trialled QKD over existing fibre infrastructure. In Italy, Retelit, Telebit, and ThinkQuantum demonstrated secure key exchange on operational networks.
Finland’s VTT-led NaQCI initiative, part of the EU’s EuroQCI programme, is developing quantum testbeds and planning cross-border links. These efforts support the EU’s objective of establishing a continent-wide quantum communication network by the end of the decade.