Prof Vlatko Vedral FInstP

Abstract:

Quantum correlation, or entanglement, is now believed to be an indispensable physical resource for certain tasks in quantum information processing, for which classically correlated states cannot be useful. Besides information processing, what kind of physical processes can exploit entanglement? In this paper, we show that there is indeed a more basic relationship between entanglement and its usefulness in thermodynamics. We derive an inequality showing that we can extract more work out of a heat bath via entangled systems than via classically correlated ones. We also analyze the work balance of the process as a heat engine, in connection with the second law of thermodynamics. ©2005 The American Physical Society.

Abstract:

A model of a thermal spin state entering a beam splitter generating entanglement was presented. A method for the generation of distillable entanglement from mixed states unitarily which utilizes the flexibility of dimension of occupied Hilbert space was also suggested. It was observed that entanglement generation was due to the truncation of the thermal spin state. The results show that the more entanglement can be generated at the higher input temperature.

Abstract:

We give a closed-form solution of von Neumann entropy as a function of geometric phase modulated by visibility and average distinguishability in Hubert spaces of two and three dimensions. We show that the same type of dependence also exists in higher dimensions albeit with other terms. For non-maximal mixing, the results become more involved and generally depend also on the probability of the states. We also outline a method for measuring both the entropy and the phase experimentally using a simple Mach-Zehnder-type interferometer which explains physically why the two concepts are related.