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Aram Harrow

University of Bristol

Entanglement Spread and Clean Resource Inequalities

November 19, 2008 - 2:10 - 2:35pm

RLE Conference Center 36-428



This talk will examine states that superpose different amounts of entanglement and protocols that generate or consume different amounts of entanglement, but run in superposition. In both cases we find a uniquely quantum difficulty: entanglement cannot be conditionally discarded without either using communication or causing decoherence.  This phenomenon, which I call entanglement spread, is surprisingly poorly understood given that is a feature of bipartite pure-state entanglement.

In my talk, I'll describe a framework for understanding and working with entanglement spread. Then I'll mention scenarios where entanglement spread does or does not present challenges/opportunities. For example, consider the question of whether there is an advantage to replacing EPR pairs with superpositions of varying amounts of entanglement: I'll show that this does not reduce the communication complexity of evaluating classical functions with distributed inputs, but can exponentially reduce the simulation cost of a bipartite unitary gate. I will also mention a number of open problems, both technical and conceptual.

Aram Harrow has been a lecturer at the University of Bristol since 2005, first in Computer Science and currently in Mathematics. Before moving to Bristol, he did an undergraduate degree (in math and physics) at MIT, followed by a Ph.D in physics with Prof. Isaac Chuang as supervisor. His research is on quantum information theory and quantum algorithms.