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.

scholarly journals Partial Bell-State Analysis with Parametric down Conversion in the Wigner Function Formalism

2010 ◽  
Vol 2010 ◽  
pp. 1-11 ◽  
Author(s):  
A. Casado ◽  
S. Guerra ◽  
J. Plácido
Keyword(s):  
Wigner Function ◽  
Beam Splitter ◽  
Bell State ◽  
Function Formalism ◽  
State Measurement ◽  
Parametric Down Conversion ◽  
Correlation Properties ◽  
Light Beams ◽  
Down Conversion ◽  
State Analysis

We apply the Wigner function formalism to partial Bell-state analysis using polarization entanglement produced in parametric down conversion. Two-photon statistics at a beam-splitter are reproduced by a wave-like description with zeropoint fluctuations of the electromagnetic field. In particular, the fermionic behaviour of two photons in the singlet state is explained from the invariance on the correlation properties of two light beams going through a balanced beam-splitter. Moreover, we show that a Bell-state measurement introduces some fundamental noise at the idle channels of the analyzers. As a consequence, the consideration of more independent sets of vacuum modes entering the crystal appears as a need for a complete Bell-state analysis.

Quantum cryptography using femtosecond-pulsed parametric down-conversion

1999 ◽  
Vol 60 (4) ◽  
pp. R2622-R2625 ◽  
Author(s):  
A. V. Sergienko ◽  
M. Atatüre ◽  
Z. Walton ◽  
G. Jaeger ◽  
B. E. A. Saleh ◽  
...  
Keyword(s):  
Quantum Cryptography ◽  
Parametric Down Conversion ◽  
Down Conversion

scholarly journals Towards Measuring Terahertz Photon Statistics by a Superconducting Bolometer

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 4964
Author(s):  
Pavel Prudkovskii ◽  
Andrey Leontyev ◽  
Kirill Kuznetsov ◽  
Galiya Kitaeva
Keyword(s):  
Photon Statistics ◽  
Statistical Distributions ◽  
Superconducting Bolometer ◽  
Thz Detection ◽  
Parametric Down Conversion ◽  
Discrete Nature ◽  
The Mean ◽  
Normal Law ◽  
The Relationship ◽  
Down Conversion

Statistical distributions of the analog readings of an antenna-coupled THz superconducting bolometer were measured and analyzed under a special type of irradiation by low-energy fluxes of THz photons with Poisson photon statistics and controllable mean photon numbers. The photons were generated via low-gain parametric down-conversion in pulse-pumped Mg:LiNbO3 crystal placed to a cooled cryostat together with the bolometer NbN film. Results of theoretical approximation of experimental histograms reveal the discrete nature of THz detection by superconducting bolometers and open a way for studying their quantum characteristics. It is shown that bolometer readings per pulse consist of discrete counts (“single charges”), with the mean number linearly dependent on the number of input photons. Contributions of single counts to a total analog reading are statistically distributed according to the normal law, with average values slightly depending on the number of counts in each reading. A general formula is proposed to describe the relationship between continuous statistical distribution of the bolometer readings and discrete quantum statistics of the incident photons.

scholarly journals Quantum Cryptography with Femtosecond Parametric Down Conversion

2002 ◽  
pp. 405-411 ◽  
Author(s):  
A. V. Sergienko ◽  
M. Atature ◽  
B. M. Jost ◽  
J. Perina ◽  
B. E. A. Saleh ◽  
...  
Keyword(s):  
Quantum Cryptography ◽  
Parametric Down Conversion ◽  
Down Conversion

Self testing quantum apparatus

2004 ◽  
Vol 4 (4) ◽  
pp. 273-286
Author(s):  
D. Mayers ◽  
A. Yao
Keyword(s):  
Quantum Information ◽  
Quantum Cryptography ◽  
Quantum State ◽  
Quantum Communication ◽  
Probability Distributions ◽  
Bell State ◽  
The Self ◽  
Local Change ◽  
Measurement Apparatus ◽  
Orthogonal Measurement

We study, in the context of quantum information and quantum communication, a configuration of devices that includes (1) a source of some unknown bipartite quantum state that is claimed to be the Bell state $\Phi^+$ and (2) two spatially separated but otherwise unknown measurement apparatus, one on each side, that are each claimed to execute an orthogonal measurement at an angle $\theta \in \{-\pi/8, 0, \pi/8\}$ that is chosen by the user. We show that, if the nine distinct probability distributions that are generated by the self checking configuration, one for each pair of angles, are consistent with the specifications, the source and the two measurement apparatus are guaranteed to be identical to the claimed specifications up to a local change of basis on each side. We discuss the connection with quantum cryptography. testing quantum apparatus (pp273-286) D. Mayers and A. Yao We study, in the context of quantum information and quantum communication, a configuration of devices that includes (1) a source of some unknown bipartite quantum state that is claimed to be the Bell state $\Phi^+$ and (2) two spatially separated but otherwise unknown measurement apparatus, one on each side, that are each claimed to execute an orthogonal measurement at an angle $\theta \in \{-\pi/8, 0, \pi/8\}$ that is chosen by the user. We show that, if the nine distinct probability distributions that are generated by the self checking configuration, one for each pair of angles, are consistent with the specifications, the source and the two measurement apparatus are guaranteed to be identical to the claimed specifications up to a local change of basis on each side. We discuss the connection with quantum cryptography.

scholarly journals Bloch-Messiah decomposition and Magnus expansion for parametric down-conversion with monochromatic pump: role of the gain

2019 ◽  
Vol 198 ◽  
pp. 00006
Author(s):  
Tobias Lipfert ◽  
Dmitri Horoshko ◽  
Giuseppe Patera ◽  
Mikhail Kolobov
Keyword(s):  
Exact Solution ◽  
Phase Mismatch ◽  
Type I ◽  
Magnus Expansion ◽  
Magnus Series ◽  
Parametric Down Conversion ◽  
Field Transformation ◽  
Down Conversion ◽  
Mismatch Angle

We consider the effect of different orders of Magnus expansion for the field transformation in type-I parametric down-conversion with a monochromatic pump. The exact solution, existing in this case, allows us to analyze the convergence of the Magnus expansion for the spectrum of squeezing and the angle of squeezing. We demonstrate how the convergence of the Magnus series depends on the parametric gain for various values of the phase mismatch. For each phase-mismatch angle we find the gain, which is the exact upper bound for the convergence of the Magnus series.

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