Entanglement, Decoherence and Correlations in a Strongly Driven Jaynes-Cummings System

2006 ◽  
Vol 13 (04) ◽  
pp. 437-444 ◽  
Author(s):  
F. Casagrande ◽  
A. Lulli
Keyword(s):  
Thermal Noise ◽  
Cavity Mode ◽  
Resonant Interaction ◽  
Cavity Field ◽  
Unitary Evolution ◽  
Level Atom ◽  
Coherent Field ◽  
Field State ◽  
Atomic Correlation ◽  
Superposition States

We consider the resonant interaction of a cavity mode with a two-level atom that is driven by a coherent field while it crosses the cavity. Starting from the cavity field in a coherent state, we show that the state of the system can reach the maximum entanglement after a unitary evolution for long enough interaction times. Also we illustrate how the generation of cavity field superposition states can allow, in the open system dynamics, the observation of their decoherence in atomic correlation measurements, for any initial cavity field state, and even under the combined effects of dissipation, thermal noise, and atomic pumping.

scholarly journals Scheme for direct measurement of the two-mode Wigner function in cavity QED and ion traps.

2000 ◽  
Vol 53 (3) ◽  
pp. 429 ◽  
Author(s):  
Shi-Biao Zheng
Keyword(s):  
Wigner Function ◽  
Cavity Qed ◽  
Ion Traps ◽  
Resonant Interaction ◽  
Cavity Field ◽  
Ion Motion ◽  
Trapped Ion ◽  
Mode Field ◽  
Level Atom ◽  
Classical Fields

A scheme is proposed for the reconstruction of two-mode entangled states in cavity QED and ion traps. For a two-mode field we show that the Wigner function can be obtained by measuring the probability of a two-level atom being in ground states after resonant interaction with two classical fields and dispersive interaction with the two-mode cavity field displaced by resonant sources. For the two-dimensional motion of a trapped ion the Wigner function is obtained by measuring the probability of the ion in its ground electronic state after displacing the ion motion and then resonantly exciting the ion.

scholarly journals Macroscopic displaced thermal field as the entanglement catalyst

2007 ◽  
Vol 7 (8) ◽  
pp. 775-781
Author(s):  
S.-B. Zheng
Keyword(s):  
Thermal Field ◽  
Cavity Mode ◽  
Thermal State ◽  
Atomic System ◽  
Photon Number ◽  
Resonant Interaction ◽  
Entangled State ◽  
Cavity Field ◽  
Average Photon Number

We show that entanglement of multiple atoms can arise via resonant interaction with a displaced thermal field with a macroscopic photon-number. The cavity field acts as the catalyst, which is disentangled with the atomic system after the operation. Remarkably, the entanglement speed does not decrease as the average photon-number of the mixed thermal state increases. The atoms may evolve to a highly entangled state even when the photon-number of the cavity mode approaches infinity.

Sub-Poissonian single-emitter laser: Coherent pump vs incoherent

2020 ◽  
Vol 35 (03) ◽  
pp. 2040026
Author(s):  
Nikolay V. Larionov ◽  
Ilya V. Safonov
Keyword(s):  
Numerical Simulation ◽  
Master Equation ◽  
Cavity Mode ◽  
Photon Statistics ◽  
Level Atom ◽  
Coherent Field ◽  
Single Emitter ◽  
Incoherent Pump

We theoretically investigate the properties of a single-emitter laser with coherent pump: two-level atom interacting with a single damping cavity mode which is resonantly excited by a coherent field. With the help of numerical simulation of the master equation we show that such pumping mechanism is more preferably than incoherent pump for achieving of sub-Poissonian photon statistics.

MAXIMUM ENTANGLEMENT IN A JAYNES-CUMMINGS SYSTEM WITH STRONGLY DRIVEN ATOMS

2006 ◽  
Vol 20 (11n13) ◽  
pp. 1613-1620 ◽  
Author(s):  
F. CASAGRANDE ◽  
A. LULLI
Keyword(s):  
Cavity Mode ◽  
Resonant Cavity ◽  
Vacuum State ◽  
Interaction Time ◽  
Von Neumann Entropy ◽  
Lower State ◽  
Von Neumann ◽  
Level Atom ◽  
Maximum Value ◽  
Coherent Field

We describe the entanglement of a Jaynes-Cummings system, where a two-level atom is also strongly driven by an external coherent field while it crosses a resonant cavity prepared in a coherent state. First we consider the atom-cavity field entanglement, described by the Von Neumann entropy. We find that it depends only on the interaction time and the initial atomic state. The entropy vanishes in the case of maximally polarized atom, independent of the interaction time, whereas it reaches its maximum value for atom in the upper or lower state and for long enough interaction times. Then we investigate the entanglement between two consecutive strongly driven atoms interacting with the cavity mode assumed in the vacuum state, showing that they never entangle in spite of the existence of atom-atom correlations.

The influence of the classical homogenous gravitational field on interaction of a three-level atom with a single mode cavity field

2015 ◽  
Vol 29 (29) ◽  
pp. 1550175 ◽  
Author(s):  
N. H. Abd El-Wahab ◽  
Ahmed Salah
Keyword(s):  
Electromagnetic Field ◽  
Gravitational Field ◽  
Photon Number ◽  
Single Mode ◽  
Temporal Behavior ◽  
Cavity Field ◽  
Text Type ◽  
Level Atom ◽  
The Mean ◽  
Single Mode Cavity

We study the interaction between a single mode electromagnetic field and a three-level [Formula: see text]-type atom in the presence of a classical homogenous gravitational field when the atom is prepared initially in the momentum eigenstate. The model includes the detuning parameters and the classical homogenous gravitational field. The wave function is calculated by using the Schrödinger equation for a coherent electromagnetic field and an atom is in its excited state. The influence of the detuning parameter and the classical homogenous gravitational field on the temporal behavior of the mean photon number, the normalized second-order correlation function and the normal squeezing is analyzed. The results show that the presence of these parameters has an important effect on these phenomena. The conclusion is reached and some features are given.

A SCHEME FOR IMPLEMENTATION OF DENSE CODING WITH W-CLASS STATES IN CAVITY QED

2009 ◽  
Vol 07 (01) ◽  
pp. 307-312 ◽  
Author(s):  
LIU YE ◽  
JUAN HE
Keyword(s):  
Cavity Qed ◽  
Cavity Mode ◽  
Dense Coding ◽  
Cavity Field ◽  
Quantum Dense Coding ◽  
Atomic States

An experimentally feasible scheme for implementing quantum dense coding in cavity QED is proposed. In the scheme a W-class state can first be prepared by letting the atoms interact simultaneously with a highly detuned cavity mode. Then the states coded on this W-class state can be exactly distinguished by detecting atomic states. The scheme is insensitive to the cavity field, and the quantum dense coding can be realized in a simple way.

scholarly journals Hydrogen spin oscillations in a background of axions and the 21-cm brightness temperature

2020 ◽  
Author(s):  
G Lambiase ◽  
S Mohanty
Keyword(s):  
Cosmic Strings ◽  
Transition Rates ◽  
Spin Temperature ◽  
Level Atom ◽  
Spin Flip ◽  
Coherent Field ◽  
Unique Method ◽  
Photon Process ◽  
The Right ◽  
The Universe

Abstract The 21-cm line signal arising from the hyperfine interaction in hydrogen has an important role in cosmology and provides a unique method for probing of the universe prior to the star formation era. We propose that the spin flip of Hydrogen by the coherent emission/absorption of axions causes a lowering of their spin temperature and can explain the stronger than expected absorption of 21-cm light reported by the EDGES collaboration. We find the analogy of axion interaction with the two level HI with the Jaynes-Cummings model of a two level atom in a cavity and we derive the spin flip frequency in this formalism and show that the coherent oscillations frequency Ω∝1/fa in contrast with the incoherent transitions between the HI hyperfine levels where the transition rates $\propto 1/f_a^2$. The axion emission and absorption rates are equal but the spin temperature is still lowered due to different selection rules for the spin flip transitions compared to the photon process. We show that the axion process goes in the right direction for explaining the EDGES observation. For this mechanism to work we require a coherent field of relativistic axions with energy Eν peaked at the 21-cm spin-flip energy. Such a coherent background of relativistic axions can arise from the decay of cosmic strings if the decay takes place in the electroweak era.

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