Atmospheric effects on satellite-mediated continuous-variable quantum key distribution

Abstract

Satellite-mediated quantum key distribution (QKD) has received considerable attention due to its potential to reach a global scale. Associated with this application is the atmospheric effects that set a notably restrict to the secret key rate. Here we demonstrate the atmospheric effects on satellite-mediated continuous-variable QKD with respect to the transmittance, fiber coupling, and excess noise. We consider the effects on both downlink and uplink while illustrating the discrepancy between them. Numerical analysis shows that downlink has more reliable transmittance than uplink while enduring a severe fiber coupling issue. It reveals that the discrepancy in transmittance is mainly due to the energy redistribution of the arriving beam. In addition, the time-of-arrival fluctuation notably reduces transmittance when the transmitted pulse half-width is sufficiently narrow (less than 10−13), and it introduces a controllable excess noise if the signal has a strong correlation with the local oscillator.

High-Rate Continuous-Variable Quantum Key Distribution with Orbital Angular Momentum Multiplexing

“…In the free space atmospheric channel, it is the atmospheric turbulence that causes the spiral spatial phase structure of the OAM beam to change, so that crosstalk occurs between different OAM modes, and as a result, an additional crosstalk noise is introduced. For the orthogonal field phase used for information encoding, atmospheric turbulence will also cause disturbance, which will also introduce an additional noise [ 43 ]. Fortunately, an existing study has shown that this phase disturbance can be eliminated by phase compensation [ 44 ].…”

Noiseless Attenuation for Continuous-Variable Quantum Key Distribution over Ground-Satellite Uplink

“…The elements of µ and Σ in the uplink case are listed in Appendix A. Based on µ and Σ, we can derive the PDT of the uplink channel through the Monte Carlo method [29], and then obtain the statistical parameters of T. Note that the simulation parameters of the work (as shown in Table 1) are the same as our previous work so that the numerical analysis of transmittance vs. zenith angle can refer to [21]. Subsequently, we demonstrate the performance of the uplink CV-QKD protocol.…”

“…Numerical analysis reveals the favorable of downlink for communication, while illustrating the urgency of an enhancement scheme for the uplink case. Note that the maximum secret key rate (ζ = 0 • ) of the downlink at 100 km is lower than that of the uplink because the fiber coupling problem is more severe in the downlink scenario [21].…”

“…As has been pointed out, the secret key rate in uplink is less than one order of magnitude compared with the downlink scenario [19]. Despite the inferior performance compared with that of the downlink, the uplink CV-QKD is also of great value owing to the simple satellite structure, the variability of quantum sources, and the accessibility for maintenance repair [20,21].…”

Enhanced Uplink Quantum Communication With Satellites via Downlink Channels

“…The main challenge faced in satellite-based quantum communications is the degradation of the signal as it is transmitted through the turbulent atmosphere of Earth [13]- [15], a degradation that is almost always larger than the noise introduced by the components used [16], [17]. It is well documented that uplink satellite laser communications is considerably more challenging compared to downlink satellite transmission: the turbulent eddies in the Earth's atmosphere have a more disruptive effect in the uplink channel.…”