Abstract The turbulence channel, as a potential medium for communications, plays a major role in establishing global quantum networks. However, the weather-tunable channel parameters have an influence on performance of quantum communication system. In this paper, we consider effects of weather conditions on attenuation of the transmission of turbulent channel and thus on performance of continuous variable quantum teleportation (CVQT). The serious weather conditions that involve snow, rain, fog and haze have been employed for security analysis of the practical system. Moreover, a linear optical amplifier is used for performance improvement in terms of the fidelity and transmission distance as well. The simulation results show that the noiseless linear optical amplifier can increase the fidelity and maximal transmission distance of the CVQT system that involves serious weather conditions. This has certain reference guides significance for information transmission in the face of various extreme weathers.
Abstract The turbulence channel, as a potential medium for communications, plays a major role in establishing global quantum networks. However, the weather-tunable channel parameters have an influence on performance of quantum communication system. In this paper, we consider effects of weather conditions on attenuation of the transmission of turbulent channel and thus on performance of continuous variable quantum teleportation (CVQT). The serious weather conditions that involve snow, rain, fog and haze have been employed for security analysis of the practical system. Moreover, a linear optical amplifier is used for performance improvement in terms of the fidelity and transmission distance as well. The simulation results show that the noiseless linear optical amplifier can increase the fidelity and maximal transmission distance of the CVQT system that involves serious weather conditions. This has certain reference guides significance for information transmission in the face of various extreme weathers.
Continuous variable quantum teleportation (CVQT) plays an important role in practical quantum communication. However, the noise and loss in the actual environment will lead to the degradation of entanglement, which has an effect on the performance of the system in terms of the transmission distance and hence hinders its implementations. In this paper, we suggest an approach to improving the performance of the CVQT system with an embedded noiseless linear amplifier (NLA). By using the NLA, one can amplify the degenerated entangled source to compensate for the attenuation of the fiber. Then we consider the influences of the available gains of the NLA on the performance of the proposed scheme under different lossy channels and entangled sources. The simulation results show that the performance is improved in fidelity and transmission distance, which may provide a feasible and effective method of putting the long-distance CVQT into practical application .
Continuous variable quantum teleportation (CVQT) is one of the technologies currently explored to implement global quantum networks. Entanglement source is an indispensable resource to realize CVQT, and its distribution process has natural symmetry. Though there are many results for CVQT over optical fiber or atmospheric channel, little attention is paid to seawater channel. In this paper, a model based on seawater chlorophyll concentration is used to study the attenuation effect of seawater on light. In our scheme, a noiseless linear amplifier is utilized for enhancing the performance of CVQT under seawater channel. Simulation results show that the proposed scheme has an improvement in terms of fidelity and maximum transmission distance compared with the original scheme.
Abstract Quantum teleportation has achieved significant progress in the optical frequency domain but faces persistent challenges, including high transmission losses and limited transmittance. In contrast, the microwave frequency domain offers distinct advantages, such as reduced absorption losses, lower energy consumption, and compatibility with superconducting quantum technologies. To overcome the limitations of optical quantum teleportation, this study presents a microwave-based continuous-variable quantum teleportation (CVQT) scheme designed for open-air environments at room temperature. The proposed approach employs microwave two-mode squeezed states, with entanglement enhanced through quantum scissors operations to mitigate environmental degradation. Numerical simulations demonstrate that the maximum transmission distance of microwave entangled states for CVQT is about 200 m at room temperature. The results also indicate that the microwave CVQT scheme achieves lower attenuation and higher fidelity over short distances compared to optical frequency CVQT under similar weather conditions. Moreover, microwave quantum states exhibit reduced sensitivity to weather-induced variations, highlighting their robustness and practicality for open-air quantum communication applications.
Quantum communication is a frontier hotspot of current research, and it has ideal information security. In order to enable quantum systems in arid and desertified areas to work almost under all-weather condition, it is necessary to study the attenuation of free-space quantum signal transmission and the influence of the turbulence atmosphere carrying sand and dust on communication performance. Using Mie scattering theory, multiple scattering simulation method, and atmospheric turbulence theory, the attenuation of optical wave transmission in sand and dust turbulent atmospheric channels with different visibility, and the influence of multiple scattering and turbulence on attenuation are studied. The results show that the effect of multiple scattering increases with the decrease of visibility, the turbulence effect gradually strengthens with the increase of distance. According to the quantum amplitude damped channel model, the effects of multiple scattering and turbulence in the sand and dust turbulent atmosphere with different visibility on the quantum channel capacity, fidelity and bit error rate are analyzed. The results show that as the visibility decreases, the multiple scattering effect increases, resulting in the decrease of attenuation and bit error rate, but an increase in channel capacity, fidelity and the boundaries of security key rate. The existence of turbulence in the dust atmosphere will increase the attenuation and bit error rate, but reduce the channel capacity, fidelity and security key rate. It can be seen that the influence of multiple scattering and turbulence on the communication performance, when the visibility of the sand and dust atmosphere are both low, cannot be ignored. In practical applications, the relevant parameters of quantum communication should be adaptively adjusted according to the visibility and turbulence intensity to improve the probability, efficiency and reliability of quantum communication.
Abstract Advances in satellite quantum communications aim at reshaping the global telecommunication network by increasing the security of the transferred information. Here, we study the effects of atmospheric turbulence in continuous-variable entanglement distribution and quantum teleportation in the optical regime between a ground station and a satellite. More specifically, we study the degradation of entanglement due to various error sources in the distribution, namely, diffraction, atmospheric attenuation, turbulence, and detector inefficiency, in both downlink and uplink scenarios. As the fidelity of a quantum teleportation protocol using these distributed entangled resources is not sufficient, we include an intermediate station for either state generation, or beam refocusing, in order to reduce the effects of atmospheric turbulence and diffraction, respectively. The results show the feasibility of free-space entanglement distribution and quantum teleportation in downlink paths up to the LEO region, but also in uplink paths with the help of the intermediate station. Finally, we complete the study with microwave-optical comparison in bad weather situations, and with the study of horizontal paths in ground-to-ground and inter-satellite quantum communication.
Free-space optical communication links are promising channels for establishing secure quantum communication. Here we study the transmission of nonclassical light through a turbulent atmospheric link under diverse weather conditions, including rain or haze. To include these effects, the theory of light transmission through atmospheric links in the elliptic-beam approximation presented by Vasylyev et al. [D. Vasylyev et al., Phys. Rev. Lett. 117, 090501 (2016)] is further generalized. It is demonstrated, with good agreement between theory and experiment, that low-intensity rain merely contributes additional deterministic losses, whereas haze also introduces additional beam deformations of the transmitted light. Based on these results, we study theoretically the transmission of quadrature squeezing and Gaussian entanglement under these weather conditions.