Practical Spatial-Division Multiplexing for QKD

Activity: Talk or presentationOral presentation


As Quantum Key Distribution (QKD) makes its transition from lab demonstrations out into real world commercial service; it is inevitable that the demand for key-bandwidth will grow, just like our demand for conventional communications bandwidth has grown over the past couple of decades. Simple techniques, such as increasing the bandwidth of a single channel can help, but when moving to GHz repetition rates will require expensive quantum (cryogenic detectors) and conventional hardware. Other innovative methods for increasing bandwidth are being explored, such as utilising high-dimensional protocols or multiplexing techniques (wavelength, spatial, temporal, or mode). Each method has different scaling of the channel capacity (equivalent to key-bandwidth). When considering the different propagation channel options, each method also has benefits and drawbacks.
In this work, we present a simple and practical way to perform spatial-division multiplexing to increase the channel capacity. With the use of a single-photon avalanche diodes (SPAD) arrays, together with a spatial and time multiplexing technique, we simulated a QKD system where more than one independent signal is sent, effectively increasing the channel capacity linearly with the number of signals sent. We will comment on the current limitations of this technology and future prospects and optimization.
Period30 Aug 2022
Event titlePhoton 2022
Event typeConference
Conference number11
Degree of RecognitionInternational