Role of intensity fluctuations in quantum cryptography with coherent states

2018 ◽  
Vol 48 (9) ◽  
pp. 843-848 ◽  
Author(s):  
D A Kronberg ◽  
Yu V Kurochkin
Keyword(s):  
Quantum Cryptography ◽  
Coherent States ◽  
Intensity Fluctuations

scholarly journals Common Coherence Witnesses and Common Coherent States

Entropy ◽  
2021 ◽  
Vol 23 (9) ◽  
pp. 1136
Author(s):  
Bang-Hai Wang ◽  
Zi-Heng Ding ◽  
Zhihao Ma ◽  
Shao-Ming Fei
Keyword(s):  
Coherent State ◽  
Coherent States ◽  
State Problem ◽  
Properties And Characterization ◽  
The Common ◽  
High Level

We show the properties and characterization of coherence witnesses. We show methods for constructing coherence witnesses for an arbitrary coherent state. We investigate the problem of finding common coherence witnesses for certain class of states. We show that finitely many different witnesses W1,W2,⋯,Wn can detect some common coherent states if and only if ∑i=1ntiWi is still a witnesses for any nonnegative numbers ti(i=1,2,⋯,n). We show coherent states play the role of high-level witnesses. Thus, the common state problem is changed into the question of when different high-level witnesses (coherent states) can detect the same coherence witnesses. Moreover, we show a coherent state and its robust state have no common coherence witness and give a general way to construct optimal coherence witnesses for any comparable states.

scholarly journals From Stochastic Optics to theWigner Formalism: The Role of the Vacuum Field in Optical Quantum Communication Experiments

Atoms ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 76 ◽  
Author(s):  
Alberto Casado ◽  
Santiago Guerra ◽  
José Plácido
Keyword(s):  
Quantum Cryptography ◽  
Physical Meaning ◽  
Quantum Communication ◽  
Bell State ◽  
Vacuum Field ◽  
Heisenberg Picture ◽  
Parametric Down Conversion ◽  
The Relationship ◽  
Down Conversion

TheWigner formalism in the Heisenberg picture constitutes a bridge that connects QuantumOptics to Stochastic Optics. The vacuum field appears explicitly in the formalism, and the wavelikeaspects of light are emphasised. In addition, the zeropoint intensity as a threshold for detection is acommon denominator in both theories. In this paper, after summarising the basic rules of the Wignerapproach and its application to parametric down-conversion, some new results are presented thatdelve into the physical meaning of the zeropoint field in optical quantum communication. Specifically,the relationship between Bell-state distinguishability and the number of sets of zeropoint modesthat take part in the experiment is analysed in terms of the coupling between the phases of thedifferent fields involved and the subtraction of the zeropoint intensity at the detectors. Additionally,the connection between the compatibility theorem in quantum cryptography and zeropoint fieldis stressed.

Generalized beam-splitting attack in quantum cryptography with dim coherent states

1999 ◽  
Vol 169 (1-6) ◽  
pp. 103-108 ◽  
Author(s):  
Miloslav Dušek ◽  
Ondřej Haderka ◽  
Martin Hendrych
Keyword(s):  
Quantum Cryptography ◽  
Coherent States ◽  
Beam Splitting

A curiosity concerning the role of coherent states in quantum field theory

Pramana ◽  
1980 ◽  
Vol 15 (1) ◽  
pp. 107-115 ◽  
Author(s):  
Abhay Ashtekar ◽  
Anne Magnon-Ashtekar
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Coherent States ◽  
Quantum Field

scholarly journals Phase sensitivity of an $\operatorname{SU}(1,1)$ interferometer via product detection

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Qingle Wang ◽  
Yami Fang ◽  
Xiaoping Ma ◽  
Dong Li
Keyword(s):  
Coherent States ◽  
The Other ◽  
Phase Sensitivity ◽  
Homodyne Detection ◽  
Quantum Metrology ◽  
Parametric Amplifiers ◽  
Detection Scheme ◽  
Beam Splitters ◽  
Cramer Rao Bound

AbstractWe theoretically analyze the phase sensitivity of an $\operatorname{SU}(1,1)$ SU ( 1 , 1 ) interferometer with various input states by product detection in this paper. This interferometer consists of two parametric amplifiers that play the role of beam splitters in a traditional Mach–Zehnder interferometer. The product of the amplitude quadrature of one output mode and the momentum quadrature of the other output mode is measured via balanced homodyne detection. We show that product detection has the same phase sensitivity as parity detection for most cases, and it is even better in the case with two coherent states at the input ports. The phase sensitivity is also compared with the Heisenberg limit and the quantum Cramér–Rao bound of the $\operatorname{SU}(1,1)$ SU ( 1 , 1 ) interferometer. This detection scheme can be easily implemented with current homodyne technology, which makes it highly feasible. It can be widely applied in the field of quantum metrology.

Counterfactual quantum cryptography based on weak coherent states

2012 ◽  
Vol 86 (2) ◽  
Author(s):  
Zhen-Qiang Yin ◽  
Hong-Wei Li ◽  
Yao Yao ◽  
Chun-Mei Zhang ◽  
Shuang Wang ◽  
...  
Keyword(s):  
Quantum Cryptography ◽  
Coherent States
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