Abstract:The secret key rate is one of the main obstacles to the practical application of continuous-variable quantum key distribution (CVQKD). In this paper, we propose a multiplexing scheme to increase the secret key rate of the CVQKD system with orbital angular momentum (OAM). The propagation characteristics of a typical vortex beam, involving the Laguerre–Gaussian (LG) beam, are analyzed in an atmospheric channel for the Kolmogorov turbulence model. Discrete modulation is utilized to extend the maximal transmission… Show more
“…The atmospheric turbulence channel can be characterized by the effective transmittance and the channel excess noise. The effective transmittance of different OAM states propagating in the atmospheric channel can be derived from the correct propagation probability of the initial mode detected by the receiver, namely [37,38]…”
Section: Properties Of the Atmospheric Turbulence Channelmentioning
confidence: 99%
“…The channel excess noise may originate from multiple sources, such as from imperfect modulation, intensity fluctuations of the used lasers, background light, and so on [41,42]. In our work, we will focus on the crosstalk noise among different OAM modes caused by the atmospheric turbulence, which can be expressed as [38]…”
Section: Properties Of the Atmospheric Turbulence Channelmentioning
Quantum teleportation is one of the fundamental primitives of quantum cryptography. In order to achieve a wider range of high-capacity information transfer, we propose a free-space quantum teleportation (QT) protocol with orbital angular momentum (OAM) multiplexed continuous variable (CV) entangled states. The preparation of the entangled states is accomplished by the spontaneous four-wave mixing (SFWM) process occurring in a hot 85Rb vapor cell, and the mode selection for the Bell-state measurement is achieved by employing the balanced homodyne detection technique. The fidelity of teleporting EPR entangled states carrying different topological charges via a Kolmogorov-type atmospheric turbulence channel is derived, and the superiority of enhancing the system channel capacity via OAM multiplexing is demonstrated. Our work provides a feasible scheme to implement high-capacity quantum communication in atmospheric environments.
“…The atmospheric turbulence channel can be characterized by the effective transmittance and the channel excess noise. The effective transmittance of different OAM states propagating in the atmospheric channel can be derived from the correct propagation probability of the initial mode detected by the receiver, namely [37,38]…”
Section: Properties Of the Atmospheric Turbulence Channelmentioning
confidence: 99%
“…The channel excess noise may originate from multiple sources, such as from imperfect modulation, intensity fluctuations of the used lasers, background light, and so on [41,42]. In our work, we will focus on the crosstalk noise among different OAM modes caused by the atmospheric turbulence, which can be expressed as [38]…”
Section: Properties Of the Atmospheric Turbulence Channelmentioning
Quantum teleportation is one of the fundamental primitives of quantum cryptography. In order to achieve a wider range of high-capacity information transfer, we propose a free-space quantum teleportation (QT) protocol with orbital angular momentum (OAM) multiplexed continuous variable (CV) entangled states. The preparation of the entangled states is accomplished by the spontaneous four-wave mixing (SFWM) process occurring in a hot 85Rb vapor cell, and the mode selection for the Bell-state measurement is achieved by employing the balanced homodyne detection technique. The fidelity of teleporting EPR entangled states carrying different topological charges via a Kolmogorov-type atmospheric turbulence channel is derived, and the superiority of enhancing the system channel capacity via OAM multiplexing is demonstrated. Our work provides a feasible scheme to implement high-capacity quantum communication in atmospheric environments.
“…It can be implemented in the discrete-variable scheme and continuousvariable scheme (CVQKD) [6,7], and the latter has the advantages of a high secret key rate (SKR) and low cost. Long-distance transmission [8] and high SKR [9,10] are the two critical goals of CVQKD, which are limited by the practical transmission loss of the quantum channel, excess noise, and reconciliation efficiency [11,12]. Therefore, maintaining high reconciliation efficiency [13,14] and low excess noise is a major obstacle to the realization of remote CVQKD.…”
Excess noise is a major obstacle to high-performance continuous-variable quantum key distribution (CVQKD), which is mainly derived from the amplitude attenuation and phase fluctuation of quantum signals caused by channel instability. Here, an excess noise suppression scheme based on equalization is proposed. In this scheme, the distorted signals can be corrected through equalization assisted by a neural network and pilot tone, relieving the pressure on the post-processing and eliminating the hardware cost. For a free-space channel with more intense fluctuation, a classification algorithm is added to classify the received variables, and then the distinctive equalization correction for different classes is carried out. The experimental results show that the scheme can suppress the excess noise to a lower level, and has a significant performance improvement. Moreover, the scheme also enables the system to cope with strong turbulence. It breaks the bottleneck of long-distance quantum communication and lays a foundation for the large-scale application of CVQKD.
“…For example, owing to the special helical phase and hollow light field of the OAM beam, OAM can be applied to micro-control technologies in the microscopic world, such as optical tweezers and micromotors [ 9 ]. As an independent degree of freedom for wireless and quantum communications, OAM can be used to achieve a higher communication capacity through the simultaneous transmission of multiple orthogonal OAM mode vortex beams [ 10 , 11 , 12 , 13 ]. It has even been suggested that telescopes equipped with OAM diagnostic instruments can be made to detect rotating black holes [ 14 , 15 ].…”
Based on plasma kinetic theory, the dispersion and Landau damping of Langmuir and ion-acoustic waves carrying finite orbital angular momentum (OAM) were investigated in the κ-deformed Kaniadakis distributed plasma system. The results showed that the peculiarities of the investigated subjects relied on the deformation parameter κ and OAM parameter η. For both Langmuir and ion-acoustic waves, dispersion was enhanced with increased κ, while the Landau damping was suppressed. Conversely, both the dispersion and Landau damping were depressed by OAM. Moreover, the results coincided with the straight propagating plane waves in a Maxwellian plasma system when κ=0 and η→∞. It was expected that the present results would give more insight into the trapping and transportation of plasma particles and energy.
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