Researchers have developed a new high-purity single-photon source that can operate at room temperature. The source is an important step toward practical applications of quantum technology, such as highly secure communication based on Quantum Key Distribution (QKD).
The team has proposed their new single-photon source and showed that it can produce over ten million single photons per second at room temperature. They also incorporated the single-photon source into a fully portable device that can perform QKD.
The new single-photon source uniquely combines a 2D material called hexagonal boron nitride with an optical component known as a hemispherical solid immersion lens, which increases the source’s efficiency by a factor of six.
Although hexagonal boron nitride has previously been used to create a single-photon source that operates at room temperature, until now researchers had not been able to achieve the efficiency needed for real-world application.
The researchers combined their new single-photon source with a custom-built portable confocal microscope that can measure the single photons at room temperature, creating a system that can perform QKD. The single-photon source and confocal microscope are housed inside a robust package that measures just 500 x 500 millimeters and weighs around 10 kilograms. The package is also engineered to deal with vibration and stray light.
Tests of the new single-photon source showed that it could achieve a single-photon collection rate of 107 Hz while maintaining excellent purity — meaning each pulse had a low probability of containing more than one photon. It also showed exceptional stability over many hours of continuous operation. The researchers also demonstrated the system’s ability to perform QKD under realistic conditions, showing that secured QKD with 20 MHz repetition rates would be feasible over several kilometers. (ScienceDaily)
The paper has been published in the journal Optics Letters.
