Is there a fundamental limit on the length of a communication channel in a single-photon quantum cryptosystem?

JETP Letters ◽  
1996 ◽  
Vol 64 (11) ◽  
pp. 866-869 ◽  
Author(s):  
S. N. Molotkov ◽  
S. S. Nazin
Keyword(s):  
Communication Channel ◽  
Single Photon ◽  
Fundamental Limit ◽  
Quantum Cryptosystem

A simulated photon-number detector in quantum information processing

2002 ◽  
Vol 2 (Special) ◽  
pp. 556-559
Author(s):  
K. Nemoto ◽  
S. Braunstein
Keyword(s):  
Quantum Information ◽  
Communication Channel ◽  
Quantum Information Processing ◽  
Single Photon ◽  
Photon Number ◽  
Homodyne Detection ◽  
Fundamental Limit ◽  
Infrared Wavelengths ◽  
Set Up ◽  
Alternative Set

A simulated photon-number detection via homodyne detectors is considered as a way to improve the efficiency near the single-photon level of communication. Current photon-number detectors at infrared wavelengths are typically characterized by their low detection efficiencies, which significantly reduce the mutual information of a bosonic communication channel. In order to avoid the inefficiency inherent in such direct photon-number detection, we evaluate an alternative set-up based on efficient dual homodyne detection. We show that replacing inefficient direct detectors with homodyne-based simulated direct detectors can yield significant improvements, even near the single-photon level of operation. However we argue that there is a fundamental limit on the ability of homodyne detection to simulate ideal photon number detection, considering the exponential gap between quantum and classical computers. This applies to arbitrarily complicated simulation strategies based on homodyne detection.

scholarly journals Quantum cryptography for secured communication networks

2020 ◽  
Vol 10 (1) ◽  
pp. 407
Author(s):  
B. Muruganantham ◽  
P. Shamili ◽  
S. Ganesh Kumar ◽  
A. Murugan
Keyword(s):  
Quantum Cryptography ◽  
Communication Networks ◽  
Communication Channel ◽  
Single Photon ◽  
Quantum States ◽  
Integer Factorization ◽  
Rsa Algorithm ◽  
Shor's Algorithm ◽  
Fiber Channels ◽  
Secured Communication

Quantum cryptography is a method for accessing data with the cryptosystem more efficiently. The network security and the cryptography are the two major properties in securing the data in the communication network. The quantum cryptography uses the single photon passing through the polarization of a photon. In Quantum Cryptography, it's impossible for the eavesdropper to copy or modify the encrypted messages in the quantum states in which we are sending through the optical fiber channels. Cryptography performed by using the protocols BB84 and B92 protocols. The two basic algorithms of quantum cryptography are Shor’s algorithm and the Grover’s’s algorithm. For finding the number of integer factorization of each photon, Shor’s algorithm is used. Grover’s’s algorithm used for searching the unsorted data. Shor’s algorithm overcomes RSA algorithm by high security. By the implementation of quantum cryptography, we are securing the information from the eavesdropper and thereby preventing data in the communication channel.

scholarly journals NUMERICAL CHARACTERIZATION OF ATMOSPHERIC EFFECTS ON AN EARTH–SPACE QUANTUM COMMUNICATION CHANNEL

2007 ◽  
Vol 05 (01n02) ◽  
pp. 241-248 ◽  
Author(s):  
N. ANTONIETTI ◽  
M. MONDIN ◽  
G. BRIDA ◽  
M. GENOVESE
Keyword(s):  
Free Space ◽  
Communication Channel ◽  
Quantum Communication ◽  
Single Photon ◽  
Atmospheric Effects ◽  
Single Photons ◽  
Atmospheric Conditions ◽  
Numerical Characterization ◽  
Simulation Results

Quantum communication in free space is the next challenge of telecommunications. Since we want to determine the outcome of a quantum communication by means of single photons, we must understand how a single photon interacts with the atmosphere. In this brief article, some simulation results for realistic and generic atmospheric conditions are reported and discussed.

scholarly journals Measurement of the Probability of a Binary Symbol «0» Erasing in a Single-Photon Asynchronous Communication Channel with a Receiver Based on a Photon Counter

2021 ◽  
Vol 12 (2) ◽  
pp. 156-165
Author(s):  
A. M. Timofeev
Keyword(s):  
Communication Channel ◽  
Optical Radiation ◽  
Detection Efficiency ◽  
Supply Voltage ◽  
Single Photon ◽  
Data Logging ◽  
Photon Counter ◽  
Optical Signals ◽  
Quantum Detection ◽  
Minimum Probability

Receiving modules of single-photon communication channels should provide the least loss of transmitted information when measuring low-power optical signals. In this regard, it is advisable to use photon counters. They are highly sensitive, but are characterized by data logging errors. Therefore, the purpose of this work was to investigate the effect of the intensity of the recorded optical radiation during the transmission of binary symbols «0» on the probability of erasing these symbols in a single-photon communication channel containing a photon counter based on an avalanche photodetector as a receiving module with a passive avalanche suppression scheme.The lower and upper threshold levels of pulses recorded at the output of the photon counter, as well as the statistical distributions of the mixture of the number of dark and signal pulses at the output of the photon counter when registering binary symbols «0» Pst0( N ) and «1» Pst1( N ) were determined. For this, a technique was used to reduce information loss. As a result, the minimum probability of erasing binary symbols «0» P(–/0) was achieved.The performed experimental results showed that to achieve the minimum probability of erasing binary symbols «0» P(–/0) = 0,11·10−2, it is important to select not only the intensity of the used optical radiation J , but also the supply voltage of the avalanche photodetector U, at which the dead time of the photon counter is −2 minimal, and its quantum detection efficiency is maximum: J0 ≥ 98,94·10−2 rel. units and U = 52,54 V. 

scholarly journals The influence of the time of single photon transmission of information on the reliability of its reception in a quantum cryptographic communication channel

2019 ◽  
pp. 67-72 ◽  
Author(s):  
A. M. Timofeev
Keyword(s):  
Mathematical Modeling ◽  
Communication Channel ◽  
Dead Time ◽  
Single Photon ◽  
Average Duration ◽  
Photon Counter ◽  
Transmission Of Information ◽  
The Dead

Expression for estimating the reliability of information during its transmission through quantum-cryptographic communication channel that contains a dead time photon counter has been obtained in this research. According to the results of mathematical modeling, the dependence of the reliability of the received data on the average time of single photon transmission of information was established. Studies have shown that with an increase in the average time of single photon transmission of information, these dependences grow, reaching saturation. Moreover, with equal parameters with an increase in the average duration of the dead time of a prolonging type, saturation occurs at large values of the average time of a single photon transmission of information.

Ultimate resolution and information in electron microscopy

1991 ◽  
Vol 49 ◽  
pp. 496-497
Author(s):  
D. Van Dyck
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Transfer Function ◽  
Information Transfer ◽  
Communication Channel ◽  
Structural Information ◽  
Information Rate ◽  
Noise Power ◽  
Signal Power ◽  
Imaging Device

An (electron) microscope can be considered as a communication channel that transfers structural information between an object and an observer. In electron microscopy this information is carried by electrons. According to the theory of Shannon the maximal information rate (or capacity) of a communication channel is given by C = B log2 (1 + S/N) bits/sec., where B is the band width, and S and N the average signal power, respectively noise power at the output. We will now apply to study the information transfer in an electron microscope. For simplicity we will assume the object and the image to be onedimensional (the results can straightforwardly be generalized). An imaging device can be characterized by its transfer function, which describes the magnitude with which a spatial frequency g is transferred through the device, n is the noise. Usually, the resolution of the instrument ᑭ is defined from the cut-off 1/ᑭ beyond which no spadal information is transferred.

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