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MP: Fachverband Theoretische und Mathematische Grundlagen der Physik

MP 1: Quanteninformation I

MP 1.3: Vortrag

Dienstag, 28. Februar 2012, 10:05–10:30, ZHG 003

Quantum fluctuations, mean field methods and the simulation of continuous quantum systems — Zoltán Kádár, •Michael Keyl, and Zoltán Zimborás — ISI Foundation, Torino, Italy

The fluctuations of a discrete quantum system behave in the infinite particle limit like a continuous system. This fact can be used to simulate a continuous system in terms of finitely many qubits. Experimental applications of this observation include the implementation of "quantum memory", which can be used to store the state of (one mode) of a light field in an atomic ensemble at room temperature. A very convenient tool to treat such models is mean field theory, where the fluctuations around a mean field observable are described in terms of "fluctuation operators". In this context we will show how products of the latter converge in a weak sense to polynomials of position and momentum of the continuous system. Based on that the relation between discreet and continuous dynamics will be analyzed, and quadratic Hamiltonians are discussed in greater detail. Finally we will have a particular look at cases where the continuous Hamiltonian is a Schrödinger operator which does not admit a selfadjoint extension.