Mark Thompson

In this work we report the first chip-to-chip multidimensional entanglement distribution. The faithful generation and transmission of the multidimensional quantum states relies on two main ingredients: silicon integrated photonics, offering a compelling platform for quantum information processing, and multicore fibres, which allows the reliable transmission of path encoded qudits.

Measurement-device-independent quantum key distribution (MDI-QKD) offers a method of distributing shared randomness for use in symmetric key cryptography, while integrated optics provides a promising platform for ubiquitous quantum communication. This work experimentally demonstrates the use of indium phosphide (InP) devices for MDI-QKD. We generate 100 ps pulses for 2 GHz clocked, time-bin encoded BB84 states with random phases through a novel gain switching technique. By interfering two independent InP devices, we achieve 50 bps at 100 km and pre-empt the availability of integrated receivers which will increase rates through inherent scalability.

As computing becomes more mobile, cashless as well as cardless payment solutions are introduced and a need arises for incorporating QKD in a mobile device. Handheld devices present a particular challenge as the orientation and the phase of a qubit will depend on device motion. This problem is addressed by the reference frame independent (RFI) QKD scheme, providing a protocol to overcome issues with calibration and slow variations in reference frames between the two communicating parties. This indicates that the real world imperfections and the impracticality of calibrating mobile devices can be mitigated to allow the adoption of integrated quantum technologies in portable systems.