Information on a Photon: Free-Space Quantum Communication (InPho: FSQC).

摘要

The investigators are developing a free-space quantum communication system that improves both the photon efficiency (long term goal of 10 bits per photon) and communication rate (long term goal of 1 Gbit/s). To achieve these worldrecord results, the system will rely on hyperentanglement in which multiple degrees of freedom (polarization and time/frequency) of the photon are entangled to transmit multiple secret bits per photon and independent communication channels using the transverse spatial degree of freedom will be used to achieve high communication rates. The investigators have achieved a spatial heralding efficiency of >90% in the hyperentangled source, distributed a quantum key with 8.3 bits/photon at a rate of 67 kbit/s and 2.2 bits/photon at a rate of 12.6 Mbits/s in a single channel, a source brightness of over 100 million photons/s into a single mode, developed single photon counting detectors with greater than 80% quantum efficiency and jitter <120 ps and explored methods for reducing detector after pulsing, evaluated commercial time taggers for the system, devised an improved error correction protocol, improved the performance of a sorter for orbital angular momentum modes, developed a method for arbitrary sorting of spatial modes, assessed the strength of atmospheric turbulence over a 1 km horizontal path, assessed multi-pixel detectors for single-photon counting, and developed new method for securing time bin quantum states.