[seminar] seminar Giampaolo, The Frustration in being Odd: area law violation in local systems, 7. 11. 2018., 11h

[Hrvoje Buljan]

Dear colleagues,

I would like to announce a Department of Physics and QiantiXLie seminar by
Salvatore Marco Giampaolo from the Institut Ruđer Bošković. The title of
the seminar is The Frustration in being Odd: area law violation in local
systems and it will be held on Wednesday November 7th 2018 (see the
attachment and below for details).

See you there
Hrvoje Buljan

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Salvatore Marco Giampaolo
Institut Ruđer Bošković, Zagreb

Title: The Frustration in being Odd: area law violation in local systems

Place: Fizički odsjek, F-201 (2. kat)
Time:  Wednesday November 7th 2018 at 11.00

I show the existence of a new quantum phase of matter that arises in
antiferromagnetic spin chains with a weak frustration, just one bond in a
large chain. This is the case, for instance, of systems with an odd number
of spins with periodic boundary conditions. Such new phase is extended,
gapless, but not relativistic: the low-energy excitations have a quadratic
(Galilean) spectrum. Locally, the correlation functions on the ground
state do not show significant deviations compared to the non-frustrated
case, but correlators involving a number of sites (or distances) scaling
like the system size display new behaviors. In particular, the von Neumann
entanglement entropy is found to follow new rules, for which neither area
law applies, nor one has a divergence of the entropy with the system size.
Such very long-range correlations are novel and of potential technological
interest. I illustrate such new phase in a few prototypical chains using
numerical simulations and I study analytically the paradigmatic example of
the Ising chain. Through these examples we argue that this phase emerges
generally in (weakly) frustrated systems with discrete symmetries.

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