Analyzing First Generation Quantum Key Distribution Protocols in LEO Satellite Networks 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 laws of quantum mechanics, any attempt of eavesdropping the key will disturb the quantum states during the quantum key distribution (QKD) process, thus revealing the presence of an eavesdropper. •The first generation QKD protocols (named as Discrete variable QKD) exploit the particle properties of the light. They are based on single photon sources.
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 and S09.
Physical factors • 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. Time driven communication
The starting window of the Quantum Satellite Communication Simulator
Calculating by constant parameters
Calculating by varying parameters
Sensitivity analysis
Optimization
Channel analysis
Simulation results These simulation results were generated by the Quantum Satellite Communication Simulator.
Figure 1. QBER values of BB84 protocol are increasing for different zenith angles in case of ground-satellite communication. The height of satellite is 2000 km above sea level.
Figure 2. QBER values of BB84 protocol are increasing for different zenith angles in case of satellite-ground communication. In this way the differences between QBER values are smaller than in ground-satellite direction.
Figure 3. 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, B. Ferenc. „Quantum Computing and Communications: An Engineering Approach”, Wiley, 2005. [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] L. Bacsardi, A. Kiss, „Overview of a Space Based Quantum Key Distribution Network”, In.Poc. 65th International Astronautical Congress, Toronto, Canada, 2014
Figure 4. QBER values of BB84 protocol in function of different response times of satellite. This result was generated by ground-satellite-ground data sending. In this case we had to take into consideration the QBER value of the satellite.
Acknowledgement This research was supported by the Hungarian Scientific Research Fund – OTKA PD-112529.