Wigner Functions for Open Quantum System: A Keldysh Field Theoretic Approach

19.06.2018 11:00 – 12:30

The Wigner function of a density matrix is a crucial construction in understanding a quantum many body system, where negativity of the Wigner function indicates the presence of non-classical correlations in the system. We developed a Keldysh field theoretic formalism for systematically calculating the Wigner characteristics function of a many body system from the Keldysh partition function with a particular
configuration of single particle classical and quantum sources. The Wigner function is then obtained through the complex Laplace transform of the characteristics function. We have applied the newly developed formalism to study the dynamics of Wigner function of a quantum system coupled to external environments and its extension to the systems where inter-particle interaction is present using diagrammatic expansion.
For a single-mode anharmonic open quantum system staring from Fock states having non-classical correlation present in the system, we have shown how the nonclassicality in the system, encoded in negativity of the Wigner function, evolves with time.

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Bâtiment: Ecole de Physique

Auditoire Stuckelberg

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