On-Chip Quantum Communication Devices

Abstract

We present here results of the Quantum Technology Flagship project UNIQORN in the area of integrated photonics for quantum communication applications. Three distinct integration platforms, namely indium phosphide based monolithic integration, polymer-based hybrid integration and the CMOScompatible silicon platform, have been employed to manufacture components and sub-systems on chip for quantum communication devices. The choice of different platforms was made to exploit the best characteristics of each platform for the intended quantum communication device. The indium phosphide platform was employed to manufacture a transmitter chip for quantum key distribution featuring laser, modulators, and attenuators. The transmitter chip was evaluated in a QKD experiment achieving a secure rate of 1 kbit/s. The polymer platform was investigated for engineering non-classical light sources. Entangled and heralded single-photon sources, based on non-linear optics, were assembled on the polymer in a hybrid fashion together with waveguides and other passive micro-optical elements. A quantum random number generator, featuring a 70% randomness extraction efficiency, was also fabricated using the polymer integration technique. An array of 32 individual single-photon avalanche diodes, operating at room temperature and featuring an onboard coincidence logic, was coupled to the chip to demonstrate direct detection of photons on the polymer. Finally, a transimpedance amplifier based on gallium arsenide high electron mobility transistors was produced with an exceptional large electrical noise clearance of 28 dB at 100 MHz.

Time-bin entanglement at telecom wavelengths from a hybrid photonic integrated circuit

“…Despite the plethora of miniaturized quantum-light sources, only a few monolithic solutions exist that enable additional functionalities such as photon filtering or splitting on-chip making hybrid integration worthwhile 11 , 12 . Here, we present a particularly versatile solution combining a nonlinear BRW with the polymer-based PolyBoard for light filtering and routing that is easily adaptable to other wavelengths, filter or encoding (e.g polarization) requirements 50 . The PIC was developed as part of the EU Quantum Flagship project Uniqorn which explored different material platforms for quantum technologies.…”

“…The PIC was developed as part of the EU Quantum Flagship project Uniqorn which explored different material platforms for quantum technologies. While hybrid integration in general is a promising way forward, the PolyBoard platform especially has proven its versatility as a host for quantum light sources, single-photon-avalanche detectors, and quantum random number generators 50 .…”

“…Finally, the newly formed hybrid PIC is mechanically stabilized by a common silicon mount with 7 x 10 mm footprint (e). A photograph (reprinted with permission from 50 ) of the final assembly used in this work ( f ). …”

“…Hybrid integration, as employed between the BRW and the PolyBoard in this work, combines the strengths of both material platforms and can also introduce new features missing in the monolithic counterparts. The PolyBoard has proven its versatility by implementing on-chip free space sections 32 , thermal phase shifters or switches 33 , tunable distributed Bragg-reflector lasers 53 , 54 , on-chip isolators and circulators 55 , 56 , and various integrated circuits for quantum photonics 50 .…”