Novel High-Speed Polarization Source for Decoy-State BB84 Quantum Key Distribution Over Free Space and Satellite Links

Abstract

To implement the BB84 decoy-state quantum key distribution (QKD) protocol over a lossy ground-satellite quantum uplink requires a source that has high repetition rate of short laser pulses, long term stability, and no phase correlations between pulses. We present a new type of telecom optical polarization and amplitude modulator, based on a balanced Mach-Zehnder interferometer configuration, coupled to a polarization-preserving sum-frequency generation (SFG) optical setup, generating 532 nm photons with modulated polarization and amplitude states. The weak coherent pulses produced by SFG meet the challenging requirements for long range QKD, featuring a high clock rate of 76 MHz, pico-second pulse width, phase randomization, and 98% polarization visibility for all states. Successful QKD has been demonstrated using this apparatus with full system stability up to 160 minutes and channel losses as high 57 dB 1 . We present the design and simulation of the hardware through the Mueller matrix and Stokes vector relations, together with an experimental implementation working in the telecom wavelength band. We show the utility of the complete system by performing high loss QKD simulations, and confirm that our modulator fulfills the expected performance.

Free-Space-Optical Quantum Key Distribution Systems: Challenges and Trends

“…In addition, the secret key rate has an important relation with the performance of the TRNG subsystems, thus, FPGAs have been used for generation and acquisition of true random digital sequences reaching 1.25 Gb/s [13]. An important issue in DP&Comm subsystems is the ability to adapt and generate countermeasures to maintain or improve the specific performance against external dynamic factors such as atmospheric turbulence in FSO links, resizing and adaptive parameters based on an optimization process [14,15]. In addition, some QKD systems use a Graphics Processing Unit (GPU) as a DP&Comm (although some considerations have to be analyzed to complete all the task of the DP&Comm) because it provides some important technical features such as parallel computing and processing floatingpoint information allowing rates of 1.35 Gb/s [16].…”

Airborne Demonstration of a Quantum Key Distribution Receiver Payload

“…Our QKD source is a significantly improved version of a previous-generation apparatus [28], implementing BB84 with decoy states [29] at 400 MHz. Weak coherent pulses at 785 nm wavelength are generated by combining a narrow-band 1590 nm continuous-wave (CW) laser (L1) with 1550 nm triggered-pulsing laser (L2) through sum frequency generation in a periodically poled magnesium oxide (PPMgO) waveguide (see Fig.…”

Airborne demonstration of a quantum key distribution receiver payload

“…Our QKD source is a significantly improved version of a previous-generation apparatus [28], implementing BB84 with decoy states [29] at 400 MHz. Weak coherent pulses at 785 nm wavelength are generated by combining a narrow-band 1590 nm continuous-wave (CW) laser (L1) with 1550 nm triggered-pulsing laser (L2) through sum frequency generation in a periodically poled magnesium oxide (PPMgO) waveguide (see Fig.…”