Simulating Secure Key Distribution over Quantum Satellite Channel András Kiss, László Bacsárdi, Institute of Informatics and Economics, University of West Hungary (NymE), Hungary kissa@gain.nyme.hu, bacsardi@inf.nyme.hu
Quantum Communications • From the engineering point of view, the quantum circuits built from different quantum gates give many possibilities to perform computational calculations in a more efficient way than the nowadays used traditional computers [1]. • Although quantum computers are still the tools of the future, there are promising quantum-based applications, mainly in the field of communication.
quantum-based satellite communications
The free-space quantum communication can be extended to ground-tosatellite or satellite-satellite quantum communication, which could be an ideal application for global quantum cryptography [2].
Research problem • The quantum satellite communication is based on the need of long distance secret communication. According to the quantum computation laws, an unknown quantum bit cannot be copied perfectly and this fact makes safe data transmission even in case of an eavesdropping attack. •There are two groups of the currently used quantum key distribution (QKD) solutions. •The first generation protocols use singe-photon sources, while coherent laser is used and the wave properties of light is exploited in the second generation protocols. This first approach is named as Discrete Variable QKD (DV-QKD), the second one is named as Continuous Variable QKD (CV-QKD). •To complete the determination of the Quantum Bit Error Rate of a DVQKD protocol, a series of derived procedures are needed to execute, which has high complexity.
The channel model • We dealt with the theoretical analysis of weak laser signal based satellite communications [3]. • The effects of aerosols and optical turbulence of the atmosphere on quantum communication, and the finite size of the detectors and the beam spreading induced by diffraction were taken into account as well. • We analyzed the quantum bit error rate (QBER) of different QKD protocols, i.e., BB84, B92, S09 and Gisin. • We take into consideration the following atmospheric influences: wind speed, season, climate, weather. • The following factors are used in calculation: total noise, wavelength, mean photon number by laser impulses, probability of polarization measuring error, quantum efficiency of detector. • Further parameters: zenith angle, aperture diameter, targeting angular error, number of detectors, mirror diameter, height above sea level.
Quantum Satellite Communication Simulator • The aim of the simulation software is to calculate performance characteristics of communication channels [4]. • The latest version of the application can be used by six scenarios: Calculating by constant parameters, Calculating by varying parameters, Sensitivity analysis, Time driven communication, Optimization, Channel analysis. The starting window of the Quantum Satellite Communication Simulator
Simulation results These simulation results were generated by the Quantum Satellite Communication Simulator.
Figure 1. Uplink (Earth-space) and downlink (space-Earth) QBER values of BB84 protocol in cases of Low Earth Orbit ranges and current and former space crafts.
Figure 2. QBER values of BB84 protocol in function of aperture diameter of the sender, the larger aperture results lower QBER values.
Figure 3. QBER values in function of mirror diameter of the receiver, the larger mirror diameter results lower QBER values.
Figure 4. QBER values of BB84, B92 and Gisin protocols are increasing in function of different heights above sea level in LEO (Low Earth Orbit) satellite orbit. This simulation result was generated by ground-satellite type data sending.
References [1] S Imre, “Quantum Computing and Communications - Introduction and Challenges” COMPUTERS & ELECTRICAL ENGINEERING 40:(1) pp134-141, 2014. [2] L. Bacsardi. „On the Way to Quantum-Based Satellite Communication”, IEEE Comm. Mag.51:(08) pp. 50-55., 2013 [3] L. Bacsardi. „Efficient Quantum Based Space Communications”, Lambert Academic Publishing, 2013. [4] A. Kiss, L. Bacsardi, „Quantum-based solutions in Low Earth Orbit Satellite Networksk”, In.Poc. H-SPACE 2016, 2016.
Figure 5. QBER results of BB84 protocol in case of data transmission between two ground stations. In the figure, there is an interesting feature at about 5000 km. From this distance two satellites are necessary to complete the data transmission.
Acknowledgement This research was supported by the Hungarian Scientific Research Fund – OTKA PD-112529.