Exploring Hilbert Space : accurate characterisation of quantum information

White, A.G. ; James, D.F.V. ; Munro, W.J. ; Kwiat, P.G.

HP Development Company

关键词: controllable state production;    tomographic reconstruction;    experimental determination of entanglement;   

RP-ID  :  HPL-2001-218

学科分类：计算机科学（综合）

美国|英语

来源: HP Labs

【 摘 要 】

We report the creation of a wide range of quantum states with controllable degrees of entanglement and entropy using an optical two-qubit source based on spontaneous parametric down conversion. The states are characterised using measures of entanglement and entropy determined from tomographically determined density matrices. The Tangle-Entropy plane is introduced as a graphical representation of these states, and the theoretic upper bound for the maximum amount of entanglement possible for a given entropy is presented. Such a combination of general quantum state creation and accurate characterisation is an essential prerequisite for quantum device development. Notes: A. G. White, Department of Physics, University of Queensland, Brisbane, Queensland 4072 Australia. D.F.V. James, Theory Division, T-4; Physics Division, P-23; Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA. P.G. Kwiat, Department of Physics, University of Illinois, Urbana-Champaign, Illinois 61801, USA 4 Pages