Dynamics of a Large–spin–boson System in the Strong Coupling Regime
نویسنده
چکیده
We investigate collective effects of an ensemble of biased two level systems interacting with a bosonic bath in the strong coupling regime. The two level systems are described by a large pseudo-spin J . An equation for the expectation value M(t) of the z-component of the pseudo spin is derived and solved numerically for an ohmic bath at T =0. In case of a large cut-off frequency of the spectral function, a Markov approximation is justified and an analytical solution is presented. We find that M(t) relaxes towards a highly correlated state with maximum value ±J for large times. However, this relaxation is extremely slow for most parameter values so as if the system was ”frozen in” by interaction with the bosonic bath.
منابع مشابه
Dynamics of a large spin with strong dissipation.
We study the generalization of the spin-boson model to spins greater than one-half in the strong-coupling regime. This model applies to dissipative large spins as well as to ensembles of identical two-state systems coupled to a common environment. Using a combination of polaron transformations and master equations, we find nonexponential spin relaxation towards one of two possible equilibrium s...
متن کاملDynamics of the sub-Ohmic spin-boson model: a comparison of three numerical approaches.
Dynamics of the sub-Ohmic spin-boson model is examined using three numerical approaches, namely the Dirac-Frenkel time-dependent variation with the Davydov D(1) ansatz, the adaptive time-dependent density matrix renormalization group method within the representation of orthogonal polynomials, and a perturbative approach based on a unitary transformation. In order to probe the validity regimes o...
متن کاملTwo-level system in spin baths: non-adiabatic dynamics and heat transport.
We study the non-adiabatic dynamics of a two-state subsystem in a bath of independent spins using the non-interacting blip approximation, and derive an exact analytic expression for the relevant memory kernel. We show that in the thermodynamic limit, when the subsystem-bath coupling is diluted (uniformly) over many (infinite) degrees of freedom, our expression reduces to known results, correspo...
متن کاملDynamics of a large spin with weak dissipation q
We investigate the generalization of the spin-boson model to arbitrary spin size. The Born–Markov approximation is employed to derive a master equation in the regime of small coupling strengths to the environment. For spin one half, the master equation transforms into a set of Bloch equations, the solution of which is in good agreement with results of the spin-boson model for weak ohmic dissipa...
متن کامل3 Dynamics of a large spin with weak dissipation ⋆
We investigate the generalization of the spin-boson model to arbitrary spin size. The Born-Markov approximation is employed to derive a master equation in the regime of small coupling strengths to the environment. For spin one half, the master equation transforms into a set of Bloch equations, the solution of which is in good agreement with results of the spin-boson model for weak ohmic dissipa...
متن کامل