# Theoretical Physics

**23 November 2016**

**Time:**15:00 to 16:00

**Location:**EC Stoner 8.62

Theoretical Physics Seminar: Ahsan Nazir (Manchester)

**Quantum Dynamics and Thermodynamics at strong reservoir coupling**

Abstract: Quantum systems are invariably open, evolving under surrounding influences rather than in isolation. Standard open quantum system methods eliminate all information on the environmental state to yield a tractable description of the system dynamics. By incorporating a collective coordinate of the environment into the system Hamiltonian, I shall explain how to circumvent this limitation [1]. The resulting theory provides straightforward access to important environmental properties that would otherwise be obscured, allowing quantification of the evolving system-environment correlations. As a direct result, I shall show that the generation of robust system-environment correlations that persist into equilibrium (heralded also by the emergence of non-Gaussian environmental states) renders the canonical system steady state almost always incorrect. The resulting equilibrium states deviate markedly from those predicted by standard perturbative techniques and are instead fully characterized by thermal states of the mapped system-collective coordinate Hamiltonian. I shall also outline how noncanonical system states could be investigated experimentally to study deviations from canonical thermodynamics [2], with direct relevance to molecular and solid-state nanosystems.

[1] J. Iles-Smith, N. Lambert, and A. Nazir, Phys. Rev. A 90, 032114 (2014)

[2] D. Newman, F. Mintert, and A. Nazir, arXiv:1609.04035

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