Researchers from the Cavendish Laboratory at Cambridge University have implemented a novel technique to generate single photons with tailored properties from solid-state devices that are identical in quality to lasers.

As their photon source, the researchers built a semiconductor Schottky diode device containing individually addressable quantum dots.  The transitions of quantum dots were used to generate single photons via resonance fluorescence – a technique demonstrated previously by the same team.

Under weak excitation, also known as the Heitler regime, the main contribution to photon generation is through elastic scattering. By operating in this way, photon decoherence can be avoided altogether. The researchers were able to quantify how similar these photons are to lasers in terms of coherence and waveform – it turned out they were identical.

“Our research has added the concepts of coherent photon shaping and generation to the toolbox of solid-state quantum photonics,” said Dr Mete Atature from the Department of Physics, who led the research.

“We are now achieving a high-rate of single photons which are identical in quality to lasers with the further advantage of coherently programmable waveform - a significant paradigm shift to the conventional single photon generation via spontaneous decay.”

There are already protocols proposed for quantum computing and communication which rely on this photon generation scheme, and this work can be extended to other single photon sources as well, such as single molecules, colour centres in diamond and nanowires.

“We are at the dawn of quantum-enabled technologies, and quantum computing is one of many thrilling possibilities,” added Atature.

“Our results in particular suggest that multiple distant qubits in a distributed quantum network can share a highly coherent and programmable photonic interconnect that is liberated from the detrimental properties of the chips. Consequently, the ability to generate quantum entanglement and perform quantum teleportation between distant quantum-dot spin qubits with very high fidelity is now only a matter of time.

This story is reprinted from material from
University of Cambridge, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.