Quantum coherence in a coupled-cavity array

2016 ◽  
Vol 30 (18) ◽  
pp. 1650114
Author(s):  
De-Wei Cao ◽  
Yixin Zhang ◽  
Jicheng Wang ◽  
Zheng-Da Hu
Keyword(s):  
Quantum Coherence ◽  
Qualitative Difference ◽  
Superfluid Transition ◽  
Entropy Measure ◽  
Coupled Cavities ◽  
Initial Correlation ◽  
Dynamical Behaviors ◽  
Level Atom ◽  
Cavity Coupling ◽  
Coupled Cavity

The dynamical properties of quantum coherence in the system of two-coupled-cavities, each of which resonantly interacts with a two-level atom, is investigated via the relative entropy measure. We focus on the coherences for the atom–atom, atom–cavity and cavity–cavity subsystems and find that the dynamical behaviors of these coherences depend largely on the cavity–cavity coupling, which may indicate the Mott insulator-superfluid transition in the thermodynamic limit. We also study the influences of the initial cavity–cavity correlation on the coherences and show that the initial correlation of the cavity–cavity subsystem can enhance the revival ability for the atom–atom and cavity–cavity coherences while reduce that for the atom–cavity coherence. Besides, we demonstrate the qualitative difference of dynamics between coherence and entanglement. Finally, the influences of dissipations including cavity losses and atomic decays on the coherence are explored.

scholarly journals Symmetry-like Relation of Relative Entropy Measure of Quantum Coherence

2020 ◽  
Author(s):  
Cheng-yang Zhang ◽  
Zhi-hua Guo ◽  
H.X. Cao
Keyword(s):  
Relative Entropy ◽  
Quantum Coherence ◽  
Quantum Physics ◽  
Information Science ◽  
Upper Bounds ◽  
Von Neumann Entropy ◽  
Entropy Measure ◽  
Lower And Upper Bounds ◽  
Von Neumann ◽  
Natural Logarithm

Quantum coherence is an important physical resource in quantum information science, and also as one of the most fundamental and striking features in quantum physics. In this paper, we obtain a symmetry-like relation of relative entropy measure $C_r(\rho)$ of coherence for $n$-partite quantum states $\rho$, which gives lower and upper bounds for $C_r(\rho)$. Meanwhile, we discuss the conjecture about the validity of the inequality $C_r(\rho)\leq C_{\ell_1}(\rho)$ for any state $\rho$. We observe that every mixture $\eta$ of a state $\rho$ satisfying $C_r(\rho)\leq C_{\ell_1}(\rho)$ and any incoherent state $\sigma$ also satisfies the conjecture. We also note that if the von Neumann entropy is defined by the natural logarithm $\ln$ instead of $\log_2$, then the reduced relative entropy measure of coherence $\bar{C}_r(\rho)=-\rho_{\rm{diag}}\ln \rho_{\rm{diag}}+\rho\ln \rho$ satisfies the inequality ${\bar{C}}_r(\rho)\leq C_{\ell_1}(\rho)$ for any mixed state $\rho$.

EVOLUTION OF ATOM-FIELD PROBABILITY IN A COUPLED CAVITY SYSTEM

2013 ◽  
Vol 22 (03) ◽  
pp. 1350029
Author(s):  
K. V. PRIYESH ◽  
RAMESH BABU THAYYULLATHIL
Keyword(s):  
Coupling Strength ◽  
Probability Amplitude ◽  
Field Coupling ◽  
Level Atom ◽  
Cavity System ◽  
Coupling Strengths ◽  
Field Excitation ◽  
Excitation Probability ◽  
Hopping Strength ◽  
Coupled Cavity

In this paper we have investigated the dynamics of two cavities each with a two-level atom, coupled together with photon hopping. The coupled cavity system is studied in single excitation subspace and the evolution of the atom (field) states probabilities are obtained analytically. The probability amplitude of states executes oscillations with different modes and amplitudes, determined by the coupling strengths. The evolution is examined in detail for different atom field coupling strength, g and field–field hopping strength, A. It is noticed that the exact atomic probability amplitude transfer occurs when g ≪ A with minimal field excitation probability and the period of probability transfer is calculated. In the limit g ≫ A there exists periodic exchange of probability between atom and field inside each cavity and also between cavity 1 and cavity 2. Periodicity of each exchange in this limit also obtained.

Cooling distant atoms into steady entanglement via coupled cavities

2013 ◽  
Vol 13 (3&4) ◽  
pp. 281-289
Author(s):  
Li Tuo Shen ◽  
Xin Yu Chen ◽  
Zhen-Biao Yang ◽  
Huai-Zhi Wu ◽  
Shi-Biao Zheng
Keyword(s):  
Steady State ◽  
Laser Cooling ◽  
Ground State ◽  
Entangled State ◽  
High Fidelity ◽  
Maximally Entangled State ◽  
Coupled Cavities ◽  
Laser Frequencies ◽  
Cavity System ◽  
Coupled Cavity

We propose a scheme for generating steady-state entanglement between two distant atomic qubits in the coupled-cavity system via laser cooling. With suitable choice of the laser frequencies, the target entangled state is the only ground state that is not excited by the lasers due to large detunings. The laser excitations of other ground states, together with dissipative processes, drive the system to the target state which is the unique steady state of the system. Numerical simulation shows that the maximally entangled state with high fidelity can be produced with presently available cooperativity.

DYNAMICS OF A COUPLED CAVITY SYSTEM COMPOSED OF THREE CAVITIES

2012 ◽  
Vol 10 (06) ◽  
pp. 1250070 ◽  
Author(s):  
ZHI-RONG ZHONG ◽  
XIU LIN ◽  
BIN ZHANG ◽  
ZHEN-BIAO YANG
Keyword(s):  
Theoretical Basis ◽  
Quantum States ◽  
Entangled States ◽  
W States ◽  
Atomic Excitation ◽  
Level Atom ◽  
Cavity System ◽  
Maximally Entangled States ◽  
The One ◽  
Coupled Cavity

We study the one-excitation dynamics of a coupled cavity system composed of three cavities, each containing a two-level atom. By adjusting the atom–cavity detuning Δ, cavity–cavity hopping rate v and the initial atomic excitation residential, a wide variety of time-evolution behaviors can be realized. Under certain conditions, the two-atom maximally entangled states and three-atom W states can be obtained. The results provide a theoretical basis for the manipulation of quantum states in such a system and will contribute to the understanding of more complex systems.

AN OPTIMIZED DYNAMICAL DECOUPLING STRATEGY TO SUPPRESS DECOHERENCE

2011 ◽  
Vol 09 (07n08) ◽  
pp. 1599-1615 ◽  
Author(s):  
SHUANG CONG ◽  
LINPING CHAN ◽  
JIANXIU LIU
Keyword(s):  
Density Matrix ◽  
Normal Distribution ◽  
Quantum Coherence ◽  
Diagonal Element ◽  
Quantum States ◽  
Time Intervals ◽  
Dynamical Decoupling ◽  
Level Atom ◽  
Reference Index ◽  
Arbitrary Quantum

In this paper, we first present a brief derivation of the dynamical decoupling condition by means of designing control Hamiltonians, which is used to preserve arbitrary quantum states in the case of interactions with environment. According to different time intervals between the adjacent pulses, two important dynamical decoupling schemes: periodic dynamical decoupling (PDD) and Uhrig dynamical decoupling (UDD) are analyzed. Based on the comparison between PDD and UDD, we propose our optimized dynamical decoupling scheme with different time intervals between adjacent pulses which follow a normal distribution. At last numerical simulations are carried out in a three-level atom in Ξ -configuration, we select the non-diagonal element of density matrix as a reference index to compare the performances of suppressing the decoherence of these three strategies, and the results indicate that dynamical decoupling strategy proposed has better performances than that of PDD and UDD have under some low range of the loss of the quantum coherence.

Coherent and incoherent laser pump on a five-level atom in a strongly coupled cavity-QED system

2022 ◽  
Vol 105 (1) ◽  
Author(s):  
Asha Devi ◽  
Sarath D. Gunapala ◽  
Malin Premaratne
Keyword(s):  
Cavity Qed ◽  
Strongly Coupled ◽  
Laser Pump ◽  
Level Atom ◽  
Coupled Cavity

Protection of quantum coherence in an open V-type three-level atom through auxiliary atoms

2019 ◽  
Vol 94 (11) ◽  
pp. 115102 ◽  
Author(s):  
Esfandyar Faizi ◽  
Bahram Ahansaz
Keyword(s):  
Quantum Coherence ◽  
Level Atom
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