Decoherence and kinetic processes in quantum nanosystems

Tuhin Datta, Madan Mohan Bajaj

BIS stands for bonding of infinitesimal signals. When an animal is killed VLF and ULF signals used to emit mingle up with surrounding objects. These signals hold many similar properties as those of the optical signals. As a consequence the nanosystems of the quantum objects become chaotic. They start showing coherence and decoherence in accordance with the situations concerned. Our focus in this paper is to discuss the fragility of coherence in the chaotic nanosystms and we will introduce a method for describing decoherence in open quantum nanosystems. We have studied here as well the very large scale integration of these infinitesimal signals and eventually the nanostructures which have become chaotic as a result of intense BIS processes.

Robert F. O’Connell

Massimiliano Esposito

In this thesis, we investigate the emergence of kinetic processes in finite quantum systems. We first generalize the Redfield theory to describe the dynamics of a small quantum system weakly interacting with an environment of finite heat capacity. We then study in detail the spin-GORM model, a model made of a two-level system interacting with a random matrix environment. By doing this, we verify our new theory and find a critical size of the environment over which kinetic processes occur. We finally study the emergence of a diffusive transport process, on a finite tight-binding subsystem interacting with a fast environment, when the size of subsystem exceeds a critical value.

Piotr Marecki

Michael B. Mensky

Tenpei Morishita, Kiyoshi Kobayashi, Akira Ishikawa

Abstract In this study, the steepest-entropy-ascent quantum thermodynamics (SEAQT) framework is used to investigate the excitation transfer (ET) dynamics of two-level nanosystems (TLSs), focusing on non-resonant processes that involve a dynamic local phonon system. In contrast to other methods based on Markovian or non-Markovian quantum master equations, SEAQT analysis always guarantees the positivity of the density operators, thus enabling the discussion of both transient and long-term dynamics of nanosystems. The findings of this study demonstrate that the relaxation time of coherent phonons, relative to the Rabi oscillation period in two TLSs, significantly affects the relaxation process of non-resonant ETs. Moreover, the degree of mutual synchronization between ET dynamics of TLSs and local (coherent) phonons can either prolong or shorten the decoherence time, presenting a way to control the coherence in nanosystems and stimulate quantum device applications.