scholarly journals A TREATMENT OF THE QUANTUM PARTIAL ENTROPIES IN THE ATOM-FIELD INTERACTION WITH A CLASS OF SCHRÖDINGER CAT STATES

2005 ◽  
Vol 03 (03) ◽  
pp. 591-602 ◽  
Author(s):  
A.-S. F. OBADA ◽  
H. A. HESSIAN ◽  
MAHMOUD ABDEL-ATY
Keyword(s):  
Coherent State ◽  
Coherent States ◽  
Stark Shift ◽  
Initial State ◽  
Field Interaction ◽  
Composite State ◽  
Quantum Dynamical ◽  
Initial States ◽  
Schrödinger Cat ◽  
Cat States

This paper is an enquiry into the circumstances under which entropy and subentropy methods can give an answer to the question of quantum entanglement in the composite state. Using a general quantum dynamical system, we obtain the analytical solution when the atom initially starts from its excited state and the field in different initial states. Different features of the entanglement are investigated when the field is initially assumed to be in a coherent state, an even coherent state (Schrödinger cate state), and a statistical mixture of coherent states. Our results show that the setting of the initial state and the Stark shift play important roles in the evolution of the sub-entropies and entanglement.

scholarly journals Stimulated emission of relic gravitons and their super-Poissonian statistics

2019 ◽  
Vol 34 (23) ◽  
pp. 1950185 ◽  
Author(s):  
Massimo Giovannini
Keyword(s):  
Coherent State ◽  
Second Order ◽  
Stimulated Emission ◽  
Initial State ◽  
Einstein Distribution ◽  
Hubble Radius ◽  
Initial States ◽  
Bose Einstein ◽  
Final Degree ◽  
Poissonian Statistics

The degree of second-order coherence of the relic gravitons produced from the vacuum is super-Poissonian and larger than in the case of a chaotic source characterized by a Bose–Einstein distribution. If the initial state does not minimize the tensor Hamiltonian and has a dispersion smaller than its averaged multiplicity, the overall statistics is by definition sub-Poissonian. Depending on the nature of the sub-Poissonian initial state, the final degree of second-order coherence of the quanta produced by stimulated emission may diminish (possibly even below the characteristic value of a chaotic source) but it always remains larger than one (i.e. super-Poissonian). When the initial statistics is Poissonian (like in the case of a coherent state or for a mixed state weighted by a Poisson distribution) the degree of second-order coherence of the produced gravitons is still super-Poissonian. Even though the quantum origin of the relic gravitons inside the Hubble radius can be effectively disambiguated by looking at the corresponding Hanbury Brown–Twiss correlations, the final distributions caused by different initial states maintain their super-Poissonian character which cannot be altered.

Teleporting the Schrödinger Cat State

1998 ◽  
Vol 12 (29n30) ◽  
pp. 1209-1216 ◽  
Author(s):  
M. H. Y. Moussa ◽  
B. Baseia
Keyword(s):  
Coherent State ◽  
Quantum Channel ◽  
Coherent States ◽  
Joint Measurement ◽  
Bell Basis ◽  
Schrödinger Cat ◽  
Schrodinger Cat State

We present a scheme for the teleportation of a coherent state or a mesoscopic superposition of coherent states — the Schrödinger-cat state. The proposal involves a mesoscopic-correlated state as the quantum channel which is generated through an adaptation of a quantum switch scheme. The required joint measurement performed in a mesoscopic Bell basis is accomplished through a technique for detection of a Schrödinger-cat state "trapped" in a cavity.

scholarly journals Engineering Schrödinger cat states with a photonic even-parity detector

Quantum ◽  
2020 ◽  
Vol 4 ◽  
pp. 239 ◽  
Author(s):  
G. S. Thekkadath ◽  
B. A. Bell ◽  
I. A. Walmsley ◽  
A. I. Lvovsky
Keyword(s):  
Time Reversal ◽  
Coherent States ◽  
Beam Splitter ◽  
Photon Number ◽  
Input State ◽  
Interference Phenomenon ◽  
Arbitrary Size ◽  
Two Component ◽  
Schrödinger Cat ◽  
Cat States

When two equal photon-number states are combined on a balanced beam splitter, both output ports of the beam splitter contain only even numbers of photons. Consider the time-reversal of this interference phenomenon: the probability that a pair of photon-number-resolving detectors at the output ports of a beam splitter both detect the same number of photons depends on the overlap between the input state of the beam splitter and a state containing only even photon numbers. Here, we propose using this even-parity detection to engineer quantum states containing only even photon-number terms. As an example, we demonstrate the ability to prepare superpositions of two coherent states with opposite amplitudes, i.e. two-component Schrödinger cat states. Our scheme can prepare cat states of arbitrary size with nearly perfect fidelity. Moreover, we investigate engineering more complex even-parity states such as four-component cat states by iteratively applying our even-parity detector.

The generalized pair coherent states and the corresponding entangled coherent states

2015 ◽  
Vol 13 (08) ◽  
pp. 1550065
Author(s):  
Won Sang Chung
Keyword(s):  
Coherent States ◽  
Density Operator ◽  
Schwarz Inequality ◽  
Bell States ◽  
Photon Statistics ◽  
Schrödinger Cat ◽  
Cat States ◽  
Reduced Density ◽  
Entangled Coherent States

In this paper, we consider the generalized Schrödinger cat states. Using these states, we obtain the corresponding quasi-Bell states and the reduced density operator. For these quasi-Bell states, we investigate the non-classical effects such as oscillatory photon statistics, sub-Poissonian property and violation of the Cauchy–Schwarz inequality.

Modified photon-added coherent states: Generation and relatedentangled states

2008 ◽  
Vol 86 (12) ◽  
pp. 1387-1392 ◽  
Author(s):  
M -L Liang ◽  
J -N Zhang ◽  
B Yuan
Keyword(s):  
Coherent State ◽  
Radiation Field ◽  
Coherent States ◽  
Hermitian Operator ◽  
Field Interaction ◽  
Wave Approximation ◽  
New Type ◽  
The One ◽  
Entangled Coherent States ◽  
03.65 Ud

We construct one new type of quantum state that we call the modified photon-added coherent state (MPACS) of the radiation field. These states are created by repeatedly applying the Hermitian operator (a + a+) to the coherent state m times. It turns out that these states are the superpositions of the coherent and the photon-added coherent states, and have highly nonclassical behavior depending on the excitation m and other parameters. The one-mode and two-mode modified entangled coherent states are also studied. MPACS can be generated through the atom-field interaction under the nonrotating wave approximation. PACS Nos.: 42.50.Dv, 03.65.Ca, 03.65.Ud

q-Deformed Barut–Girardello su(1, 1) coherent states and Schrödinger cat states

2017 ◽  
Vol 193 (3) ◽  
pp. 1844-1852 ◽  
Author(s):  
Yuefeng Zhao ◽  
Yan Zeng ◽  
Honggang Liu ◽  
Qi Song ◽  
Gangcheng Wang ◽  
...  
Keyword(s):  
Coherent States ◽  
Schrödinger Cat ◽  
Cat States

scholarly journals Quantum macroscopic nature of cat-like states

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Andrew Carlisle
Keyword(s):  
Coherent State ◽  
Important Class ◽  
Schrödinger Cat ◽  
Cat States ◽  
Do So

AbstractWe investigate the macroscopic quantumness of a set of stateswell approximating the important class of coherent state-encoded Schrödinger cat states. We do so by using two different quantifiers of macroscopic quantumness, finding consistency between the results arising from the two quantifiers, despite the different grounds upon which they are built.

scholarly journals The semiclassical limit on a star-graph with Kirchhoff conditions

2021 ◽  
Vol 11 (2) ◽  
Author(s):  
Claudio Cacciapuoti ◽  
Davide Fermi ◽  
Andrea Posilicano
Keyword(s):  
Coherent State ◽  
Quantum Particle ◽  
Semiclassical Limit ◽  
Quantum Evolution ◽  
Star Graph ◽  
Classical Dynamics ◽  
Initial State ◽  
Scattering Operators ◽  
Initial States ◽  
Adjoint Operators

AbstractWe consider the dynamics of a quantum particle of mass m on a n-edges star-graph with Hamiltonian $$H_K=-(2m)^{-1}\hbar ^2 \Delta $$ H K = - ( 2 m ) - 1 ħ 2 Δ and Kirchhoff conditions in the vertex. We describe the semiclassical limit of the quantum evolution of an initial state supported on one of the edges and close to a Gaussian coherent state. We define the limiting classical dynamics through a Liouville operator on the graph, obtained by means of Kreĭn’s theory of singular perturbations of self-adjoint operators. For the same class of initial states, we study the semiclassical limit of the wave and scattering operators for the couple $$(H_K,H_{D}^{\oplus })$$ ( H K , H D ⊕ ) , where $$H_{D}^{\oplus }$$ H D ⊕ is the Hamiltonian with Dirichlet conditions in the vertex.

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