SP Seminar 15.12.2015 @SISSA: Paul Fendley

[Condensed Matter Section]

-------- Forwarded Message --------
Subject: 	SP Seminar 15.12.2015 @SISSA: Paul Fendley
Date: 	Sat, 12 Dec 2015 21:18:48 +0100
From: 	Vincenzo Alba <valba at sissa.it>
Reply-To: 	joint ICTP/SISSA Statistical Physics Group Seminars 
<statistical_physics_seminar at lists.ictp.it>
To: 	statistical_physics_seminar at lists.ictp.it



JOINT ICTP/SISSA STATISTICAL PHYSICS SEMINAR

Tuesday, 15th December - 11:00 am

SISSA, room 128


*****************************************************************
Speaker: Paul Fendley (University of Oxford)

Title: Strong Zero Modes and Eigenstate Phase Transitions

Abstract: Gapless edge or zero modes surviving the presence of
disorder are common in a topological phase of matter. ``Weak'' zero
modes, guaranteeing ground-state degeneracy, necessarily survive
throughout a topological phase,  A more dramatic effect occurs in the
Ising chain/Majorana wire:  ``strong'' edge zero modes result in
identical spectra in even and odd fermion-number sectors, up to
exponentially small finite-size corrections. There is a presumption
that disorder is necessary to stabilize strong zero modes in the
presence of interactions, but I show that their presence in a clean
system is not a free-fermionic fluke. In this talk I display
explicitly a strong zero mode in the XYZ chain/coupled Majorana wires;
this operator possesses some remarkable structure apparently unknown
in the integrability literature.  I also present evidence for strong
zero modes in the parafermionic cae, implying the existence of an
unconventional ``eigenstate phase transition'' where the strong zero
mode disappears, leaving only the weak one.

*****************************************************************