Polynomial scheme for time evolution of open and closed quantum systems

Jing, Jun; Ma, Hongru

doi:10.1103/physreve.75.016701

Cited by 15 publications

(13 citation statements)

References 27 publications

(64 reference statements)

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“…(ii) For the evaluation of the evolution operator U(t) = exp(iHt), we apply the Laguerre polynomial expansion scheme, which is proposed by us [20,29,37], into the computation.…”

Section: B Calculation Methodsmentioning

confidence: 99%

Controllable dynamics of two separate qubits in Bell states

2007

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The dynamics of entanglement and fidelity for a subsystem of two separate spin-1/2 qubits prepared in Bell states is investigated. One of the subsystem qubit labelled A is under the influence of a Heisenberg XY spin-bath, while another one labelled B is uncoupled with that. We discuss two cases: (i) the number of bath spins N → ∞; (ii) N is finite: N = 40. In both cases, the bath is initially prepared in a thermal equilibrium state. It is shown that the time dependence of the concurrence and the fidelity of the two subsystem qubits can be controlled by tuning the parameters of the spin-bath, such as the anisotropic parameter, the temperature and the coupling strength with qubit A. It is interesting to find the dynamics of the concurrence is independent of four different initial Bell states and that of the fidelity is divided into two groups.

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“…(ii) For the evaluation of the evolution operator U(t) = exp(iHt), we apply the Laguerre polynomial expansion scheme, which is proposed by us [20,29,37], into the computation.…”

Section: B Calculation Methodsmentioning

confidence: 99%

Controllable dynamics of two separate qubits in Bell states

2007

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“…[26] to reduce the computer resources greatly. The physics of this suppression was found to be the effect of the antiferromagnetic ordering of the bath spins in x direction.…”

Section: Discussionmentioning

confidence: 99%

“…The evolution operator U(t) can be evaluated by the efficient algorithm of polynomial schemes [24,25,26]. The method used in this calculation is the Laguerre polynomial expansion method we proposed in Ref.…”

Section: Calculation Proceduresmentioning

confidence: 99%

“…The method used in this calculation is the Laguerre polynomial expansion method we proposed in Ref. [26], which is pretty well suited to this problem and can give accurate result in a comparatively smaller computation load. More precisely, the evolution operator U(t) is expanded in terms of the Laguerre polynomial of the Hamiltonian as:…”

Section: Calculation Proceduresmentioning

confidence: 99%

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Suppression of decoherence by bath ordering

景俊

马红孺

2007

Chinese Phys.

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The dynamics of two coupled spins-1/2 coupled to a spin-bath is studied as an extended model of the Tessieri-Wilkie Hamiltonian [1]. The pair of spins served as an open subsystem were prepared in one of the Bell states and the bath consisted of some spins-1/2 is in a thermal equilibrium state from the very beginning. It is found that with the increasing the coupling strength of the bath spins, the bath forms a resonant antiferromagnetic order. The polarization correlation between the two spins of the subsystem and the concurrence are recovered in some extent to the isolated subsystem. This suppression of the subsystem decoherence may be used to control the quantum devices in practical applications.

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“…This was followed by the introduction of improved techniques for the computation of density of states, correlation functions, and transport coefficients in disordered materials. Techniques employing orthogonal polynomials, such as Chebyshev expansionbased algorithms (Leforestier et al, 1991;Petitfor and Weaire, 1985;Tal-Ezer and Kosloff, 1984) and the kernel polynomial method (KPM), have shown superior performance (Weiße et al, 2006) and are experiencing growing popularity for studying the dynamics of quantum systems (Fehske et al, 2009;Jing and Ma, 2007). Consequently, they find a considerable range of applications in chemistry and physics, including the fields of disordered systems, electron-phonon interactions, quantum spin systems, and strongly correlated quantum systems (Boehnke et al, 2011;Ganahl et al, 2014;Viswanath and Müller, 1994).…”

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confidence: 99%