For secure data transmission quantum cryptography will be used. Inexpensive emitters of single photons are of essence for mass applications. Emitting more than one photon at a time leads to photon number splitting (PNS) which allows eavesdropping.
Technical Description
The presently only known cost effective approach potentially allowing room temperature operation is to use an LED with Bragg reflectors and an oxide aperture, well known from VCSEL technology, to emit single photons from single quantum dots (QD) placed below or above, but in the center of the aperture. Including a piezoelectric actuator allows the tuning of cavity by external stress and making the emission energy tunable. The lateral and vertical expansion of the actuator with applied voltage controls the cavity modes and QD emission energy. This allows tuning of the Bragg mirror transmission with the QD emission energy.
The yield of single photons is also increased together with an increase of the possible bit rate to the Gbit/s range.
Possible Applications
The invention is fundamental for the mass production of inexpensive single photon emitters based on standard semiconductor technologies for quantum cryptography.
Figure: Exemplary embodiment of the single photon emitter
Benefits
Large single photon yield and bit rate
Large Purcell and quality factors
Compensation of temperature fluctuation
Technology Readiness Level
Technology validated in lab (TRL: 4)
