Quasiprobability distribution for the photon-number operator and quadrature operator in a coherent state

1997 ◽  
Vol 9 (6) ◽  
pp. 995-1016 ◽  
Author(s):  
V Perinová ◽  
A Luks ◽  
J Krepelka
Keyword(s):  
Coherent State ◽  
Photon Number ◽  
Number Operator ◽  
Quasiprobability Distribution

Generating new nonclassical state by repeatedly operating number operator on coherent state

2021 ◽  
pp. 2150167
Author(s):  
Gang Ren ◽  
Jian-Ming Du ◽  
Wen-Hai Zhang
Keyword(s):  
Quantum Optics ◽  
Coherent State ◽  
Quantum State ◽  
Quantum Communication ◽  
Photon Number ◽  
Number Operator ◽  
Squeezing Effect ◽  
Nonclassical State ◽  
Poissonian Statistics ◽  
Photon Number Distribution

In this paper, using the principle of quantum state superposition, we report a nonclassical quantum state which is constructed by repeatedly operating the number operator on the coherent state. Nonclassical effects of this state are discussed by photon-number distribution, sub-Poissonian statistics, anti-bunching and negativity of Wigner function and squeezing effect. Our work provides an important nonclassical resource, which may be used in quantum communication and quantum optics.

Comparative analysis of properties for amplified coherent state and amplified squeezed vacuum

2020 ◽  
Vol 34 (33) ◽  
pp. 2050377
Author(s):  
Yan-Bei Cheng ◽  
Sheng-Guo Guan ◽  
Zu-Jian Wang ◽  
Xue-Xiang Xu
Keyword(s):  
Comparative Analysis ◽  
Coherent State ◽  
Amplification Factor ◽  
Annihilation Operator ◽  
Photon Number ◽  
Matrix Elements ◽  
Squeezed Vacuum ◽  
Quadrature Squeezing ◽  
Antibunching Effect ◽  
Analytical Expressions

Two “amplified” quantum states, that is, amplified coherent state (ACS) and amplified squeezed vacuum (ASV), are considered in this paper by applying operator [Formula: see text] on coherent state (CS) and squeezed vacuum (SV), respectively. Here [Formula: see text] [Formula: see text] denotes a amplification factor and [Formula: see text]) denote the creation (annihilation) operator. Along these two lines, we make a comparative analysis of properties for ACS and ASV. The considered properties include density matrix elements, Wigner function, mean photon number, second-order autocorrelation function, and quadrature squeezing. We derive analytical expressions and make numerical simulations for all the properties. The noteworthy results include: (1) the ACS has antibunching and squeezing characters; (2) the ASV will have the bunching and antibunching effect in small initial squeezing.

Signal characters and non-classical properties of quadratically amplified squeezed vacuum

2020 ◽  
pp. 2150028
Author(s):  
Qiang Ke ◽  
Yi-Fan Wang ◽  
Yan-Bei Cheng ◽  
Xue-Xiang Xu
Keyword(s):  
Wigner Function ◽  
Photon Number ◽  
Quadratic Function ◽  
Interaction Parameters ◽  
Intensity Noise ◽  
Number Operator ◽  
Squeezing Effect ◽  
Squeezed Vacuum ◽  
Antibunching Effect ◽  
Noise Squeezing

Based on the squeezed vacuum (SV) and the quadratic function of the photon number operator, we introduce the quadratically amplified squeezed vacuum (QASV) in this paper. We study the intensity, noise, squeezing effect, antibunching effect, and Wigner function of the QASVs. Compared with the SV, the QASVs have distinctive signal characters and possess peculiar non-classical properties in the proper range of interaction parameters.

On the Squeezing and Displacement of nth-Order

1997 ◽  
Vol 11 (09n10) ◽  
pp. 399-406
Author(s):  
Norton G. de Almeida ◽  
Célia M. A. Dantas
Keyword(s):  
Coherent State ◽  
Coherent States ◽  
Photon Number ◽  
Natural Generalization ◽  
Statistical Properties ◽  
Number Distribution ◽  
Quantum Statistical ◽  
Photon Number Distribution

The norder expressions for the squeezed and coherent states are derived as a natural generalization of the usual squeezed coherent and coherent states. The photon number distribution of n order of squeezed coherent states that are eigenstates of the operators [Formula: see text] is derived. The n order coherent state is a particular case of the states that we are now deriving. Some mathematical and quantum statistical properties of these states are discussed.

Amplified thermal state: Properties and decoherence

2021 ◽  
pp. 2150448
Author(s):  
Zheng-Yin Zhao ◽  
Xue-Xiang Xu
Keyword(s):  
Light Intensity ◽  
Amplification Factor ◽  
Thermal State ◽  
Signal To Noise Ratio ◽  
Photon Number ◽  
Gaussian State ◽  
Matrix Elements ◽  
Number Operator ◽  
Signal To Noise ◽  
Photon Loss

In this paper, we introduce the amplified thermal state (ATS) by operating [Formula: see text] on the thermal state (TS). Here, [Formula: see text] is the amplification factor and [Formula: see text] is the photon number operator. We study its properties, such as light intensity, signal-to-noise ratio (SNR), Fock matrix elements and Wigner function. In addition, we study its decoherence in photon-loss channel by analyzing evolution of all above properties. All considered properties are derived analytically and simulated numerically. Compared with the original TS, the amplification can enhance light intensity and SNR, remain the mixed character, and exhibit non-Gaussianity. While the decoherence will weaken light intensity and SNR, remain the mixed character, and return to Gaussian state.

Experimental resources needed to implement photon number splitting attack in quantum cryptography

2022 ◽  
Vol 19 (2) ◽  
pp. 025203
Author(s):  
S P Kulik ◽  
K S Kravtsov ◽  
S N Molotkov
Keyword(s):  
Coherent State ◽  
Quantum Key Distribution ◽  
Distribution Systems ◽  
Communication Channel ◽  
Random Phase ◽  
Photon Number ◽  
Fock States ◽  
Fock State ◽  
Experimental Parameters ◽  
Photon Number Splitting Attack

Abstract The analysis of the security of quantum key distribution systems with respect to an attack with nondemolishing measurement of the number of photons (photon number splitting—PNS attack) is carried out under the assumption that in the communication channel in each parcel there is a pure Fock state with a different number of photons, and the distribution of states by number of photons has Poisson statistics. In reality, in the communication channel in each parcel there are not individual Fock states, but a pure coherent state with a random phase—a superposition of Fock states with different numbers of photons. The paper analyzes the necessary experimental resources necessary to prepare individual Fock states with a certain number of photons from the superposition of Fock states for a PNS attack. Optical schemes for implementing such an attack are given, and estimates of experimental parameters at which a PNS attack is possible are made.

Photon-catalyzed optical coherent states generated via a non-degenerate parametric amplifier with quantum-optical catalysis

2020 ◽  
Vol 98 (2) ◽  
pp. 119-124 ◽  
Author(s):  
Hong-Chun Yuan ◽  
Xue-Xiang Xu ◽  
Heng-Mei Li ◽  
Ye-Jun Xu ◽  
Xiang-Guo Meng
Keyword(s):  
Coherent State ◽  
Wigner Function ◽  
Coherent States ◽  
Laguerre Polynomial ◽  
Photon Number ◽  
Parametric Amplifier ◽  
Normalization Factor ◽  
Nonclassical Properties ◽  
Quadrature Squeezing ◽  
Quantum Optical

We theoretically generate a kind of photon-catalyzed optical coherent states (PCOCSs) by heralded interference between any photons and coherent state via a non-degenerate parametric amplifier, which is also just a Laguerre polynomial excited coherent state. Based on obtaining the probability of successfully detecting them (also the normalization factor), the nonclassical properties of the PCOCSs are analytically investigated according to autocorrelation function, quadrature squeezing, and the negativity of the Wigner function. It is found that the nonclassicality depends on the amplitude of the coherent state, the catalysis photon number, and amplifier parameter. The negative volume of their Wigner function can be enlarged by increasing the catalysis photon number. These parameters may be effectively used to improve and enhance the nonclassical characteristics.

ENTANGLEMENT OF AMPLITUDE AND OPTICAL PHASE INVOLVED IN THE EPR EIGENSTATE

2000 ◽  
Vol 14 (27n28) ◽  
pp. 967-973 ◽  
Author(s):  
HONGYI FAN ◽  
YUE FAN
Keyword(s):  
Difference Operator ◽  
Photon Number ◽  
Single Mode ◽  
The State ◽  
Total Momentum ◽  
Phase Operator ◽  
Number Operator ◽  
Optical Phase ◽  
Nonlinear Phase ◽  
The Common

By noticing that although single-mode Susskind–Glogower phase operator does not commute with photon number operator, two-mode nonlinear phase operator commutes with number-difference operator. We reveal that the common eigenstate <η| of two-particles' relative coordinate and total momentum involves the entanglement between phase and amplitude. We also reveal entanglement between number difference and amplitude inherent in the state |D,|η|>, where [Formula: see text] is a deductive state of |η>.

scholarly journals DYNAMICS OF STATES IN THE NONLINEAR INTERACTION REGIME BETWEEN A THREE-LEVEL ATOM AND GENERALIZED COHERENT STATES AND THEIR NON-CLASSICAL FEATURES

2012 ◽  
Vol 26 (05) ◽  
pp. 1250027 ◽  
Author(s):  
M. K. TAVASSOLY ◽  
F. YADOLLAHI
Keyword(s):  
Coherent State ◽  
Coherent States ◽  
Exact Analytical Solution ◽  
Photon Number ◽  
Single Mode ◽  
Level Atom ◽  
Special Cases ◽  
Interaction Regime ◽  
Atomic Population Inversion ◽  
Poissonian Statistics

The present study investigates the interaction of an equidistant three-level atom and a single-mode cavity field that has been initially prepared in a generalized coherent state. The atom–field interaction is considered to be, in general, intensity-dependent. We suppose that the nonlinearity of the initial generalized coherent state of the field and the intensity-dependent coupling between atom and field are distinctly chosen. Interestingly, an exact analytical solution for the time evolution of the state of atom–field system can be found in this general regime in terms of the nonlinearity functions. Finally, the presented formalism has been applied to a few known physical systems such as Gilmore–Perelomov and Barut–Girardello coherent states of SU(1,1) group, as well as a few special cases of interest. Mean photon number and atomic population inversion will be calculated, in addition to investigating particular non-classicality features such as revivals, sub-Poissonian statistics and quadratures squeezing of the obtained states of the entire system. Also, our results will be compared with some of the earlier works in this particular subject.

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