Probabilistically perfect quantum cloning and unambiguous state discrimination

2010 ◽  
Vol 283 (19) ◽  
pp. 3818-3824 ◽  
Author(s):  
Wen-Hai Zhang ◽  
Jie-Lin Dai ◽  
Zhuo-Liang Cao ◽  
Ming Yang
Keyword(s):  
Quantum Cloning ◽  
State Discrimination ◽  
Unambiguous State Discrimination

Unambiguous State Discrimination Attack on the B92 Protocol of Quantum Key Distribution with Single Photons

2021 ◽  
Vol 24 (3) ◽  
Author(s):  
D. B. Horoshko ◽  
S. Ya. Kilin
Keyword(s):  
Quantum Key Distribution ◽  
Single Photon ◽  
Key Distribution ◽  
Single Photons ◽  
Single Photon Source ◽  
Quantum Cloning ◽  
State Discrimination ◽  
Photon Source ◽  
Unambiguous State Discrimination ◽  
B92 Protocol

We consider an unambiguous state discrimination attack on the B92 protocol of quantum key distribution, realized on the basis of polarization encoding of photons produced by a single-photon source. We calculate the secure key rate and the maximal tolerable loss for various overlaps between two signal states employed in this protocol. We make also a comparison with a physically impossible attack of perfect quantum cloning, and show that the unambiguous state discrimination is much more dangerous for the B92 protocol, than this attack, demonstrating thus, that the security of quantum key distribution is not always based on the no-cloning theorem.

scholarly journals Heralded orthogonalisation of coherent states and their conversion to discrete-variable superpositions

2017 ◽  
Vol 4 (1) ◽  
pp. 35-43 ◽  
Author(s):  
Regina Kruse ◽  
Christine Silberhorn ◽  
Tim Bartley
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Coherent States ◽  
Quantum Information Processing ◽  
Fundamental Property ◽  
Discrete Variable ◽  
Successful Operation ◽  
State Discrimination ◽  
Unambiguous State Discrimination

Abstract The nonorthogonality of coherent states is a fundamental property which prevents them from being perfectly and deterministically discriminated. Here, we present an experimentally feasible protocol for the probabilistic orthogonalisation of a pair of coherent states, independent of their amplitude and phase. In contrast to unambiguous state discrimination, a successful operation of our protocol is heralded without measuring the states. As such, they remain suitable for further manipulation and the obtained orthogonal states serve as a discretevariable basis. Therefore, our protocol doubles as a simple continuous-to-discrete variable converter, which may find application in hybrid continuous-discrete quantum information processing protocols.

scholarly journals Zero-error attacks and detection statistics in the coherent one-way protocol for quantum cryptography

2007 ◽  
Vol 7 (7) ◽  
pp. 639-664 ◽  
Author(s):  
C. Branciard ◽  
N. Gisin ◽  
N. Lutkenhaus ◽  
V. Scarani
Keyword(s):  
Quantum Cryptography ◽  
Careful Analysis ◽  
Beam Splitting ◽  
Statistical Parameters ◽  
Experimental Scheme ◽  
State Discrimination ◽  
Unambiguous State Discrimination ◽  
Better Than

This is a study of the security of the Coherent One-Way (COW) protocol for quantum cryptography, proposed recently as a simple and fast experimental scheme. In the zero-error regime, the eavesdropper Eve can only take advantage of the losses in the transmission. We consider new attacks, based on unambiguous state discrimination, which perform better than the basic beam-splitting attack, but which can be detected by a careful analysis of the detection statistics. These results stress the importance of testing several statistical parameters in order to achieve higher rates of secret bits.

scholarly journals Implementation of POVMs by Projective Measurements and Postselection:Optimal Strategies and Applications to Unambiguous State Discrimination

Proceedings ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 56
Author(s):  
Filip B. Maciejewski ◽  
Michał Oszmaniec
Keyword(s):  
Quantum Measurement ◽  
Optimal Strategy ◽  
Quantum Measurements ◽  
State Discrimination ◽  
General Quantum ◽  
Projective Measurements ◽  
Unambiguous State Discrimination

We present new results concerning simulation of general quantum measurements (POVMs) by projective measurements (PMs) for the task of Unambiguous State Discrimination (USD). We formulate a problem of finding optimal strategy of simulation for given quantum measurement. The problem can be solved for qubit and qutrits measurements by Semi-Definite Programming (SDP) methods.

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