scholarly journals Modeling and Simulation for Performance Evaluation of Optical Quantum Channels in Quantum key Distribution Systems

2021 ◽  
Vol 17 (2) ◽  
pp. 31-44
Author(s):  
Adil Fadhil Mushatet ◽  
Shelan Khasro Tawfeeq

In this research work, a simulator with time-domain visualizers and configurable parameters using a continuous time simulation approach with Matlab R2019a is presented for modeling and investigating the performance of optical fiber and free-space quantum channels as a part of a generic quantum key distribution system simulator. The modeled optical fiber quantum channel is characterized with a maximum allowable distance of 150 km with 0.2 dB/km at =1550nm. While, at =900nm and =830nm the attenuation values are 2 dB/km and 3 dB/km respectively. The modeled free space quantum channel is characterized at 0.1 dB/km at =860 nm with maximum allowable distance of 150 km also. The simulator was investigated in terms of the execution of the BB84 protocol based on polarizing encoding with consideration of the optical fiber and free-space quantum channel imperfections and losses by estimating the quantum bit error rate and final secure key. This work shows a general repeatable modeling process for significant performance evaluation. The most remarkable result that emerged from the simulated data generated and detected is that the modeling process provides guidance for optical quantum channels design and characterization for other quantum key distribution protocols.

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
M. Avesani ◽  
L. Calderaro ◽  
M. Schiavon ◽  
A. Stanco ◽  
C. Agnesi ◽  
...  

AbstractThe future envisaged global-scale quantum-communication network will comprise various nodes interconnected via optical fibers or free-space channels, depending on the link distance. The free-space segment of such a network should guarantee certain key requirements, such as daytime operation and the compatibility with the complementary telecom-based fiber infrastructure. In addition, space-to-ground links will require the capability of designing light and compact quantum devices to be placed in orbit. For these reasons, investigating available solutions matching all the above requirements is still necessary. Here we present a full prototype for daylight quantum key distribution at 1550 nm exploiting an integrated silicon-photonics chip as state encoder. We tested our prototype in the urban area of Padua (Italy) over a 145 m-long free-space link, obtaining a quantum bit error rate around 0.5% and an averaged secret key rate of 30 kbps during a whole sunny day (from 11:00 to 20:00). The developed chip represents a cost-effective solution for portable free-space transmitters and a promising resource to design quantum optical payloads for future satellite missions.


2014 ◽  
Vol 51 (9) ◽  
pp. 090603
Author(s):  
王剑 Wang Jian ◽  
朱勇 Zhu Yong ◽  
周华 Zhou Hua ◽  
苏洋 Su Yang ◽  
朱波 Zhu Bo

Entropy ◽  
2020 ◽  
Vol 22 (12) ◽  
pp. 1393
Author(s):  
Andrei Gaidash ◽  
Anton Kozubov ◽  
Svetlana Medvedeva ◽  
George Miroshnichenko

In this paper, we consider the influence of a divergence of polarization of a quantum signal transmitted through an optical fiber channel on the quantum bit error rate of the subcarrier wave quantum key distribution protocol. Firstly, we investigate the dependence of the optical power of the signal on the modulation indices’ difference after the second phase modulation of the signal. Then we consider the Liouville equation with regard to relaxation in order to develop expressions of the dynamics of the Stokes parameters. As a result, we propose a model that describes quantum bit error rate for the subcarrier wave quantum key distribution depending on the characteristics of the optical fiber. Finally, we propose several methods for minimizing quantum bit error rate.


2017 ◽  
Vol 17 (3&4) ◽  
pp. 209-241
Author(s):  
Walter O. Krawec

In this paper, we derive key-rate expressions for different quantum key distribution protocols. Our key-rate equations utilize multiple channel statistics, including those gathered from mismatched measurement bases - i.e., when Alice and Bob choose incompatible bases. In particular, we will consider an Extended B92 and a two-way semi-quantum protocol. For both these protocols, we demonstrate that their tolerance to noise is higher than previously thought - in fact, we will show the semi-quantum protocol can actually tolerate the same noise level as the fully quantum BB84 protocol. Along the way, we will also consider an optimal QKD protocol for various quantum channels. Finally, all the key-rate expressions which we derive in this paper are applicable to any arbitrary, not necessarily symmetric, quantum channel.


2011 ◽  
Vol 11 (11&12) ◽  
pp. 937-947
Author(s):  
Hong-Wei Li ◽  
Zhen-Qiang Yin ◽  
Shuang Wang ◽  
Wan-Su Bao ◽  
Guang-Can Guo ◽  
...  

In practical quantum key distribution system, the state preparation and measurement have state-dependent imperfections comparing with the ideal BB84 protocol. If the state-dependent imperfection can not be regarded as an unitary transformation, it should not be considered as part of quantum channel noise introduced by the eavesdropper, the commonly used secret key rate formula GLLP can not be applied correspondingly. In this paper, the unconditional security of quantum key distribution with state-dependent imperfections will be analyzed by estimating upper bound of the phase error rate in the quantum channel and the imperfect measurement. Interestingly, since Eve can not control all phase error in the quantum key distribution system, the final secret key rate under constant quantum bit error rate can be improved comparing with the perfect quantum key distribution protocol.


Author(s):  
Garrett Simon ◽  
Blake Huff ◽  
William Meier ◽  
Lee Harrell

Measurement-Device-Independent Quantum Key Distribution (MDI-QKD) is a two-photon protocol devised to eliminate eavesdropping attacks that interrogate or control the detector in realized quantum key distribution systems. In MDI-QKD, the measurements are carried out by an untrusted third party, and the measurement results are announced openly. Knowledge or control of the measurement results gives the third party no information about the secret key. Error-free implementation of the MDI-QKD protocol requires the crypto-communicating parties, Alice and Bob, to independently prepare and transmit single photons that are physically indistinguishable, with the possible exception of their polarization states. In this paper, we apply the formalism of quantum optics and Monte Carlo simulations to quantify the impact of small errors in wavelength, bandwidth, polarization and timing between Alice's photons and Bob's photons on the MDI-QKD quantum bit error rate (QBER). Using published single-photon source characteristics from two-photon interference experiments as a test case, our simulations predict that the finite tolerances of these sources contribute (4.04+/-20/Nsifted) to the QBER in an MDI-QKD implementation generating an Nsifted-bit sifted key.


Author(s):  
Hiền

Phân phối khoá lượng tử QKD (Quantum Key Distribution) là giải pháp có khả năng đảm an ninh vô điều kiện nhờ áp dụng luật cơ lượng tử để phân phối khóa an toàn giữa hai bên hợp pháp với sự hiện diện của kẻ nghe lén. Sử dụng vệ tinh để phân phối khóa lượng tử tới các trạm mặt đất qua kênh quang không gian tự do FSO (Free Space Optic) là giải pháp hứa hẹn tạo ra một mạng QKD phạm vi toàn cầu. Tuy nhiên, do ảnh hưởng của kênh FSO, đặc biệt là nhiễu loạn khí quyển, tốc độ truyền khóa bí mật SKR (Secret Key Rate) của các hệ thống QKD hiện tại bị hạn chế. Do đó, nghiên cứu này đề xuất mô hình hệ thống QKD đa kênh dựa trên ghép kênh phân chia theo bước sóng WDM (Wavelength Division Multiplexing) và ghép kênh sóng mang phụ SCM (Sub Carrier Multiplexing) nhằm tăng SKR. Sử dụng phương pháp phân tích lý thuyết với các công cụ giải tích và xác suất, nhóm tác giả đã xây dựng các công thức tính toán SKR và tỉ lệ lỗi bit lượng tử của hệ thống đề xuất. Kết quả khảo sát hiệu năng cho thấy, hệ thống QKD đa kênh cho phép cải thiện SKR so với hệ thống đơn kênh trong khi vẫn đảm bảo yêu cầu về QBER (Quantum Bit Error Rate).


Author(s):  
Josue Aaron Lopez-Leyva ◽  
Ariana Talamantes-Alvarez ◽  
Miguel A. Ponce-Camacho ◽  
Edith Garcia-Cardenas ◽  
Eduardo Alvarez-Guzman

2008 ◽  
Author(s):  
Xiao Tank ◽  
Lijun Ma ◽  
Alan Mink ◽  
Tiejun Chang ◽  
Hai Xu ◽  
...  

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