Berlin 2014 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 71: Quantum information: Concepts and methods VI

Q 71.4: Vortrag

Freitag, 21. März 2014, 17:15–17:30, Kinosaal

Novel condition for a quantum state to be Gaussian — Lucas Happ¹, •Maxim A. Efremov¹, Hyunchul Nha^2,3, and Wolfgang P. Schleich¹ — ¹Institut für Quantenphysik and Center for Integrated Quantum Science and Technology (IQST), Universität Ulm, D-89081 Ulm, Germany — ²School of Computational Sciences, Korea Institute for Advanced Study, Seoul 130-012, Korea — ³Department of Physics, Texas A & M University at Qatar, PO Box 23874, Doha, Qatar

Gaussian states play a major role in quantum information with continuous variables. An important question for any practical implementation of such a state is to provide a user with a criterion or condition to verify that a given state is a Gaussian one. The obvious criterion for a pure state is the positivity of the corresponding Wigner function. However, this simple and fundamental criterion of Gaussianity is not easy to verify in practice.

For this reason, we introduce in this talk a new condition to distinguish a non-Gaussian state from a Gaussian one. Our considerations are based on the fact that any Gaussian state is fully characterized by the vector formed by the first moments and the covariance matrix. We examine the proposed condition, which relies on the sum of the all moments of the coordinate and momentum operators, for pure and mixed states.