Osnabrück 2002 – scientific programme

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Q: Quantenoptik

Q 213: Quantum Information I

Q 213.6: Talk

Tuesday, March 5, 2002, 15:15–15:30, HS 11/215

Conditions for the local manipulation of Gaussian states — •Jens Eisert and Martin B. Plenio — Imperial College of Science, Technology and Medicine, London SW7 2BW, UK

Imagine a physical device that is able to manipulate locally the state of a composite quantum system by actions on its parts. Which state transformations could this device implement in principle? This is the motivating question of the theory of state transformations. While for pure states of finite-dimensional systems this theory is well-developed, the general question of the local interconvertability between entangled Gaussian states in continuous-variable systems has not been addressed before. We present a general necessary and sufficient criterion for the possibility of a state transformation from one mixed Gaussian state to another of a bi-partite two-mode system. The class of operations that will be considered is the set of local Gaussian completely positive maps. This set of operations can be realized in quantum optical systems with present technology.