A set of oscillators in a common bath

Fardin Kheirandish, Arezoo Mahmoudsalehi, Nooshin Saadatnia

In this paper the quantum dynamics of two non-interacting quantum oscillator interacting with a common heatbath is investigated by introducing a new Lagrangian. The quantum Langevin equation for each oscillator is obtained and different dissipative cases are discussed. The transient probability amplitudes among energy levels for one oscillator are obtained up to the second order time-dependent perturbation theory and the way that the oscillators are interacting due to the common bath is discussed.

Yang Zhao, G.H. Chen

E. B. Davies

G. W. Ford, Robert F. O’Connell

Here the problem considered is that of a pair of oscillators coupled to a common heat bath. Many, if not most, discussions of a single operator coupled to a bath have used the independent oscillator model of the bath. However, that model has no notion of separation, so the question of phenomena when the oscillators are near one another compared with when they are widely separated cannot be addressed. Here the Lamb model of an oscillator attached to a stretched string is generalized to illustrate some of these questions. The coupled Langevin equations for a pair of oscillators attached to the string at different points are derived and their limits for large and small separations obtained. Finally, as an illustration of a different phenomenon, the fluctuation force between a pair of masses attached to the string is calculated, with closed-form expressions for the force at small and large separations.

Xian-Ting Liang

In this paper we firstly obtain two kinds of effective spectral density functions by setting the cut-off frequencies of baths be infinite and finite. Secondly, we investigate the reduced dynamics of open qubits in four kinds of systems constructed with the basic spin-boson model. It is shown that the qubit has different dynamics governed by the two kinds of spectral density functions. In addition, we obtained that a qubit coupled to an intermediate harmonic oscillator has longer decoherence and relaxation times as they are coupled to a common bath than to their respective baths. In solving the dynamics of qubits we use a numerically exact algorithm, iterative tensor multiplication algorithm based on the quasiadiabatic propagator path integral scheme.

Paolo Tombesi