ICTP Seminar Series in CMSP - Thursday 5 May at 14:30 - Stasi Seminar Room - U. SCHNEIDER

[Condensed Matter Section]

ICTP Seminar Series in Condensed Matter and Statistical Physics
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PLEASE NOTE CHANGE IN TIME - afternoon

THURSDAY 5 May at 14:30 a.m.
Luigi Stasi Seminar Room, 1st floor, Leonardo Building


Ulrich SCHNEIDER
Cavendish Laboratory, University of Cambridge


PROBING BAND TOPOLOGY IN SYNTHETIC QUANTUM MATTER


Abstract:
Topology and geometry are fundamental to our understanding of modern
physics, underlying many foundational concepts from high energy theories,
quantum information, and condensed matter physics. In condensed matter
systems, a wide range of phenomena stem from the geometry of the band
eigenstates, the most prominent examples being the Quantum Hall Effect and
Topological Insulators, which are governed by the Berry curvature of
isolated bands. For general multi-band systems, the geometry of Hilbert
space is encoded in the matrix-valued Wilson line, giving rise to more
intricate transport phenomena and holding the potential for holonomic
quantum computing.
I will start with an introduction into these concepts and then present
interferometric measurements of Bloch band geometry using ultracold atoms
in optical lattices. In analogy to an Aharonov-Bohm interferometer that
measures magnetic flux, we realized an atomic interferometer measureing
Berry curvature in momentum space. For our graphene-type hexagonal optical
lattice, this interferometer enabled us to directly observe the singular
pi-Berry flux localized at each Dirac point.
We furthermore engineered strong-force dynamics in Bloch bands that are
described by Wilson lines and observed an evolution in the band
populations that directly reveals band geometry. Our techniques enable a
full determination of the dispersion relations, band eigenstates, Berry
curvature distributions, and topological invariants, including single- and
multi-band Chern and Z2 numbers.
Time permitting, I’ll also present a short update on our activities
regarding Many-Body Localization (MBL).