Berlin 2005 – scientific programme

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Q: Quantenoptik und Photonik

Q 42: Quanteninformation II

Q 42.6: Talk

Tuesday, March 8, 2005, 15:15–15:30, HU Audimax

Entanglement Witnesses in Spin Models — •Geza Toth — Theoretical Division, Max Planck Institute for Quantum Optics, Hans Kopfermann Str. 1, D 85748 Garching, Germany

Entanglement witnesses have recently raised a lot of attention as powerful tools for detecting quantum entanglement. They are usually multi-qubit operators which must be decomposed into a sum of local operators for measurement.

In our presentation we follow a different route. We construct entanglement witnesses using fundamental quantum operators of spin models which are easy to measure. By choosing the Hamiltonian as such an operator, our method can be used for detecting entanglement by energy measurement. We apply this method to the Heisenberg model in a cubic lattice with a magnetic field, the XY model and other familiar spin systems.

Our method can efficiently be used for entanglement detection in spin systems in thermal equilibrium. It is of experimental interest that for many familiar spin lattices energy can be measured indirectly through correlation measurements. For further details please see quant-ph/0406061.