Quantum communication can overcome the intrinsic security drawbacks of classical encryption technology, as the unique approach that is theoretically proven to be unconditionally secure so far. The most important components in quantum communication system include single-photon detector, quantum random number generator, and single-photon frequency conversion, whose parameters directly limit the performance of quantum communication system.
1. Single-photon detectors
Single-photon avalanche diodes (SPAD) operating in Geiger mode have distinct advantages such as low-cost, small-size and without requiring ultralow temperature cooling. Therefore, using such devices is the primary approach for applications requiring single-photon detection in practice. We will carry out the following researches in this direction:
(1) Design and fabrication of high-efficiency and low-noise InGaAs/InP SPADs.
(2) Design of high-performance quenching electronics and monolithically integrated circuits.
(3) Applications of SPADs in quantum communication and Lidar.
(4) High-efficiency Silicon SPADs.
2. Quantum random number generator
Quantum random number generator (QRNG) can produce random numbers that are unpredictable, irreproducible and unbiased, based on the fundamental principles of quantum physics. QRNG is another core component in quantum communication system. We will carry out the following researches in this direction:
(1) Ultrafast generation of quantum random numbers.
(2) Miniaturized real-time QRNG.
(3) Device-independent QRNG that is to generate genuine quantum randomness and to resolve the problems of entropy estimation errors and the corresponding bias due to the imperfections of realistic devices.
3. Frequency conversion in single photon level
We focus on the newly up-conversion single photon detector based on the periodically poled lithium niobate(PPLN) waveguide and its application on the Quantum Key Distribution、Optical Time Domain Reflectometer and Wind Doppler Lidar.
- Compact all-fiber polarization-independent up-conversion single-photon detector. Optics Communications (2019).
- A monolithic readout circuit for high-frequency sine wave gating single-photon detection. 49 (2018). doi:10.1117/12.2502329
- Compact and lightweight 1.5 $\mu$ m lidar with a multi-mode fiber coupling free-running InGaAs/InP single-photon detector. Review of Scientific Instruments 89, 103106 (2018).
- Device-independent quantum random-number generation. Nature 3562, 548 (2018).
- High-Speed Device-Independent Quantum Random Number Generation without a Detection Loophole. Physical Review Letters 120, 010503 (2018).
- Miniaturized high-frequency sine wave gating InGaAs/InP single-photon detector. Review of Scientific Instruments 89, 123104 (2018).
- 125 GHz sine wave gating InGaAs/InP single-photon detector with a monolithically integrated readout circuit. Optics Letters 42, 5090 (2017).
- Fully integrated free-running InGaAs/InP single-photon detector for accurate lidar applications. Optics Express 25, 14611 (2017).
- Note: A 10 Gbps real-time post-processing free physical random number generator chip. Review of Scientific Instruments 88, 096105 (2017).
- Random Number Generation with Cosmic Photons. Physical Review Letters 118, 140402 (2017).