Performance Improvement of Underwater Continuous-Variable Quantum Key Distribution via Photon Subtraction

Abstract

Considering the ocean water's optical attenuation is significantly larger than that of Fiber Channel, we propose an approach to enhance the security of underwater continuous-variable quantum key distribution (CVQKD). In particular, the photon subtraction operation is performed at the emitter to enhance quantum entanglement, thereby improving the underwater transmission performance of the CVQKD. Simulation results show that the photon subtraction operation can effectively improve the performance of CVQKD in terms of underwater transmission distance. We also compare the performance of the proposed protocol in different water qualities, which shows the advantage of our protocol against water deterioration. Therefore, we provide a suitable scheme for establishing secure communication between submarine and submarine vehicles.

Improving Underwater Continuous-Variable Measurement-Device-Independent Quantum Key Distribution via Zero-Photon Catalysis

“…Fortunately, to lengthen the transmission distance, the non-Gaussian operations [ 22 ] like single photon subtraction (SPS) [ 23 ] and zero-photon catalysis (ZPC) [ 24 ] are the most commonly used means. One article has put forward a plan of operating single photon subtraction (SPS) in the fiber-based CVQKD [ 25 ]. In this paper, we dedicate to lengthen the transmission distance of underwater CVQKD via the Gaussian operations.…”

Trans-Media Continuous-Variable Quantum Key Distribution via Untrusted Entanglement Source

“…where L is vertical propagation distance, N are optical wavenumber, and R 2 n is the refraction index structure parameters [20].…”

Nonclassicality via the Superpositions of Photon Addition and Subtraction and Quantum Decoherence for Thermal Noise

“…where ,̄represent, respectively, the dissipative coefficient and the average thermal photon number of the environment. Especially, Equation 17describes the amplitude damping (or photon loss) model when̄→ 0 and is finite [47] ; however, for̄→ ∞ and → 0, thus̄is finite, Equation (17) refers to the thermal channel in the case of the diffusion limit. Using the entangled state representation, the density-operator evolution for thermal noise can be obtained as the infinitive Kraus operator-sum representation for the density operator (t), that is described by [45,46] (t) = ∑ i,j=0…”

“…Notably, entanglement distillation realized by the superpositions of photon addition and subtraction can considerably increase the entanglement of the initial states and improve the performance of quantum processing protocols. [10][11][12][13] Therefore, so far, the output states after photon addition and subtraction may provide new physical carriers for certain quantum information technologies and fulfil some crucial quantum information tasks, such as quantum teleportation, [14,15] key distribution, [16,17] precision measurement, [18] and metrology. [19] For any realistic nonclassical light field, quantum noise in its surrounding environment can partly or fully give rise to the decrease of the nonclassicality of this field.…”