scholarly journals Dephasing Process of a Single Atom Interacting with a Two-Mode Field

Entropy ◽  
2021 ◽  
Vol 23 (2) ◽  
pp. 252
Author(s):  
Eied M. Khalil ◽  
Kamal Berrada ◽  
Sayed Abdel-Khalek ◽  
Beida Alsubei ◽  
Hichem Eleuch
Keyword(s):  
Density Operator ◽  
Single Atom ◽  
Two Photon ◽  
Damping Effect ◽  
Phase Damping ◽  
Mode Field ◽  
Finite Dimensional ◽  
Qubit System ◽  
Pair Coherent State ◽  
Photon Addition

We consider the interaction of a qubit system with a two-mode field in the presence of multi-photon transition and phase damping effect. We use the master equation to obtain the density operator when the qubit is initially prepared in its excited state and the field is in a finite-dimensional pair coherent state. The properties of the considered system, such as the population inversion, amount of the mixedness, parameter estimation, and squeezing, are explored for one- and two-photon transitions. The effects of photon addition to the field and phase damping on the evaluation of these quantumness measures are also investigated.

scholarly journals The Hilbert space of quantum gravity is locally finite-dimensional

2017 ◽  
Vol 26 (12) ◽  
pp. 1743013 ◽  
Author(s):  
Ning Bao ◽  
Sean M. Carroll ◽  
Ashmeet Singh
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Hilbert Space ◽  
Quantum Gravity ◽  
Density Operator ◽  
Small Region ◽  
Quantum Field ◽  
Locally Finite ◽  
Finite Dimensional ◽  
Model Independent

We argue in a model-independent way that the Hilbert space of quantum gravity is locally finite-dimensional. In other words, the density operator describing the state corresponding to a small region of space, when such a notion makes sense, is defined on a finite-dimensional factor of a larger Hilbert space. Because quantum gravity potentially describes superpositions of different geometries, it is crucial that we associate Hilbert-space factors with spatial regions only on individual decohered branches of the universal wave function. We discuss some implications of this claim, including the fact that quantum-field theory cannot be a fundamental description of nature.

DIAGONALIZATION OF A HAMILTONIAN DESCRIBING A SINGLE TWO-LEVEL ATOM INTERACTING WITH A TWO MODE AMPLIFIER

2007 ◽  
Vol 21 (02) ◽  
pp. 211-220 ◽  
Author(s):  
PAUL BRACKEN
Keyword(s):  
Basis Set ◽  
Single Atom ◽  
Two Photon ◽  
Level Atom ◽  
Probability Densities ◽  
Physical Phenomena

A Hamiltonian which describes the interaction of a single atom with two photon modes is introduced. It is shown that the Hamiltonian can be diagonalized in a particular basis. The energies and an eigenvector basis set are obtained. Some quasi-probability densities are calculated using amplitudes determined with respect to the rotated basis. Some of the physical phenomena which are manifested in the calculations are discussed.

INTERACTION OF A THREE-LEVEL ATOM WITH A SINGLE-MODE FIELD IN A TWO PHOTON RESONANT CAVITY

2011 ◽  
Vol 25 (03) ◽  
pp. 417-431
Author(s):  
DEBRAJ NATH ◽  
P. K. DAS
Keyword(s):  
Electromagnetic Field ◽  
Resonant Cavity ◽  
Single Mode ◽  
Atomic Level ◽  
Atomic Inversion ◽  
Cooperative Effects ◽  
Two Photon ◽  
Mode Field ◽  
Level Atom ◽  
Successive Passage

In this paper we discuss an extension of Jaynes–Cummings model by adding a further atomic level to support a second resonance and cooperative effects in multi-atom systems. A successive passage of a three-level atom in the V configuration interacting with one quantized mode of electromagnetic field in a cavity will be considered to study atomic inversion and entropy evolution of the state.

DIPOLE SQUEEZING OF THE ATOM IN A TWO-ATOM SYSTEM: EFFECTS OF THE SUPERPOSITION STATES

1994 ◽  
Vol 08 (18) ◽  
pp. 2525-2538 ◽  
Author(s):  
MUBEEN A. MIR
Keyword(s):  
Single Atom ◽  
Squeezed State ◽  
Atomic Polarization ◽  
Initial Field ◽  
Two Photon ◽  
Transition Mechanism ◽  
The One ◽  
Superposition States ◽  
Atom System ◽  
Photon Multiplicity

Dipole squeezing of the atom in the presence of another atom is investigated for the one-photon and two-photon transition mechanism with the initial atoms in the two-atom squeezed state and the field in a vacuum, a coherent, or a squeezed state. For a vacuum input, the degree of squeezing is shown to depend on the photon multiplicity 'm' and the superposition angles of the atoms, θ1 and θ2. One of the quadratures of the atomic polarization is found to exhibit permanent squeezing only for some nonzero values of θ1, as well as θ2. The effect of θ2 on the dipole squeezing, however, is found to be negligible for the initial field in a coherent or a squeezed state. A comparison with the dipole squeezing of a single atom is also presented.

Using Exchange Attenuation to Control Non-Disentanglement Quantum Information Transport in Phase Damping Channel

2013 ◽  
Vol 760-762 ◽  
pp. 1666-1669
Author(s):  
Ju Ju Hu ◽  
Qiang Ke ◽  
Hai Jiang Hu ◽  
Ying Hua Ji
Keyword(s):  
Quantum Information ◽  
Decay Rate ◽  
Information Exchange ◽  
External Environment ◽  
Energy Relaxation ◽  
Phase Damping ◽  
Decoherence Time ◽  
Qubit System ◽  
Different Types ◽  
Information Transport

It is effective to constitute a hybrid qubit system by taking advantages of different types of qubits to overcome the effects of decoherence and achieve quantum information transport. We find that energy relaxation exists in the process of information exchange bewteen the hybrid qubits. Combining this kind of energy relaxation with the decoherence effects from external environment, quantum information transport of non-disentangled effect can be achieved in phase damping channel if the exchange decay rate and decoherence time satisfy certain constraint relations.

Effects of a phase-damping cavity on entanglement and purity loss in two-qubit system

2015 ◽  
Vol 14 (6) ◽  
pp. 2043-2053 ◽  
Author(s):  
A.-S. F. Obada ◽  
H. A. Hessian ◽  
A.-B. A. Mohamed ◽  
M. Hashem
Keyword(s):  
Phase Damping ◽  
Qubit System
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