Usually, an elementary light source – such as an excited atom or molecule – emits light at an unpredictable instance in time. This spontaneous emission of light is a fundamental process within applications such as LEDs and lasers. However, for other applications it is desirable to receive single photons (light) at a specific moment with as little uncertainty as possible. For instance, this property is crucial for ultra-secure communication using quantum cryptography. Therefore, an important research goal is to fabricate a quantum light source that emits a single photon exactly at a desired moment in time.
Switching light emission
The average emission time of quantum light sources can be reduced by locating them in various nanostructures, such as optical resonators or waveguides. The smallest uncertainty in the emission time is then limited by the type of nanostructure used and the variations in the preparation time of the emitter.
Read more at: Phys.org