Optical quantum technologies—the use of the quantum properties of light to benefit from quantum-enhanced performances in communications, computation, simulation and sensing—require highly efficient single photon sources. Such devices are difficult to fabricate and the sources that have been most widely used so far present an efficiency intrinsically limited to few percents.
Within the framework of the ERC StG QD-CQED, the team of Pr. Pascale Senellart developed a new generation of single photon sources based on semiconductor quantum dots in cavities that are more than an order of magnitude more efficient. However, the technology was only accessible to quantum optics highly-trained specialists and big research facilities with enough resources to acquire the expensive optical collection setup as well as the highly stabilized cryostats required to benefit from the source performances.
The objective of this project was to develop an affordable prototype of a cryo-cooled plug-and-play single photon source. Such prototype is a critical step to allow crossing the chasm toward the single-photon source industrialisation.
To do so, we developed experimental techniques and various components to integrate a single mode fiber directly to the source. Various geometries were explored and tested in terms of alignment accuracy and impact on the source performances. We also adapted acryo-cooler with the necessary packaging for the source
integration in order to test the robustness of our fiber-integrated source to multiple cooling cycles. The project also allowed to conduct extensive benchmakring of the single photon sources, produced jointly by the CNRS and Quandela. This experimental study led to a publication in ACS Photonics.
The project did not allow to fully finalise a viable prototype of integrated cryocooled source, it set the grounds for future work now pursued within Quandela, a start-up company commercializing single photon sources created in 2017. The development of the cryo-cooled fibered single photon source, a challenge that has been further supported by the French Innovation Funds ILab, for which Quandela was elected Grand Lauréat in July 2018.
