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SUMMARY:Stationary states and (quasi)local charges in a semi-infinite chai
 n - Maurizio Fagotti (École Normale Supérieure)
DTSTART:20160111T140000Z
DTEND:20160111T150000Z
UID:TALK64617@talks.cam.ac.uk
CONTACT:INI IT
DESCRIPTION:Motivated by the remarkable fact that a local defect can have 
 global effects  on the dynamics of local observables after global quenches
 \, I revisit the  conserved quantities of the quantum XY model with open b
 oundary conditions. I  present two approaches to determine the local conse
 rvation laws. A direct method  that relies on the diagonalization of the m
 odel and a more abstract procedure  based on a correspondence between quad
 ratic forms of fermions and  block-Toeplitz-plus-Hankel operators. Specifi
 cally\, I establish the conditions  that the symbol of a particular class 
 of block-Toeplitz-plus-Hankel operators  must satisfy in order to commute 
 with a given block-Toeplits. I exhibit new  families of (quasi)local conse
 rvation laws and discuss some physical  consequences of the results.&nbsp\
 ;
LOCATION:Seminar Room 1\, Newton Institute
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