Source: Journal of Laser & Infrared  30^th Mar 2026

The controlled generation of single photons is a crucial foundation for quantum technologies such as quantum networks and quantum computing. A research team including Humboldt-Universität zu Berlin in Germany has achieved the fastest optical control operations in diamond quantum systems to date using femtosecond (1 femtosecond = 1 quadrillionth of a second) ultrafast laser pulses, providing a new technical pathway for the efficient and controlled generation of single photons. This research marks an important step toward the practical application of diamond-based quantum communication and distributed quantum computing technologies. The related findings were published in the latest issue of the journal Nature Communications.

For a long time, a major challenge in quantum technology has been how to use lasers to control qubits while clearly detecting the photons emitted by the qubits and utilizing them as information carriers. Traditional methods often rely on complex optical filtering techniques, which not only reduce system efficiency but also limit future large-scale applications.

Partial experimental setup for quantum physics experiments in the laboratory of the Department of Physics at Humboldt-Universität zu Berlin, Adlershof Campus.

The new method developed by the research team solves the above-mentioned problems. They focused on a special diamond crystal with a specific defect in its atomic structure, known as the "tin-vacancy center" or "color center". These atomic structures can act as stable qubits, capable of storing and processing quantum information and coupling with photons.

Using the new method, the team excited the quantum system with two precisely controlled laser pulses, making it easier to distinguish the control lasers from the single photons carrying quantum information, thereby significantly improving photon utilization efficiency.

Ultrafast laser pulses bring quantum state manipulation into an entirely new time scale, enabling faster and more complex quantum operations and laying the foundation for building practical quantum communication networks. In addition, the study found that the new method can preserve the internal quantum spin states of the system. This achievement also brings diamond quantum repeaters and distributed quantum computers one step closer to practical application.