[QIP-Sem] MIT Quantum Information Processing Seminar Reminder

[QIP-Sem Mailing List]

There will be no QIP seminar on Monday April 12, due to a cancellation.

Since Monday the 19th is Patriot's Day, following week's MIT QIP 
seminar will take place on TUESDAY, April 20 at 16:00 in 4-237, and 
features:


Entanglement Beyond Subsystems

by Lorenza Viola (J. R. Oppenheimer Fellow, CCS-3, Los Alamos National Lab)

ABSTRACT

Characterizing and quantifying quantum correlations in complex 
systems is critical for quantum information science as well as for a 
variety of physical phenomena, including phase transitions in matter. 
In this talk, I will discuss a generalization of entanglement based 
on the idea that entanglement is relative to a distinguished subspace 
of physical observables rather than a distinguished subsystem 
decomposition.  For multi-qubit systems, conventional entanglement is 
recovered in the special case where the set of all local observables 
on individual subsystems is preferred. By going beyond the standard 
distinguishable-subsystem framework, however, generalized 
entanglement naturally lends itself to applications in the 
condensed-matter setting.  In particular, by focusing on the 
illustrative case of a one-dimensional spin-1/2 XY model in a 
transverse field, I will show how generalized entanglement provides 
useful diagnostic tools for identifying broken-symmetry quantum phase 
transitions.

References:
- "A subsystem-independent generalization of entanglement," H. 
Barnum, E. Knill, G. Ortiz, R. Somma, and L. Viola, Phys. Rev. Lett. 
92, 107902 (2004).
- "Nature and measure of entanglement in quantum phase transitions," 
R. Somma, G. Ortiz, H. Barnum, E. Knill, and L. Viola, 
quant-ph/0403035.
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