SP and CMSP Seminars - Thursday 24 at 2:00 p.m. and Friday 25 January 11:00 a.m.

[CM Section]

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NEW - Joint ICTP/SISSA Statistical Physics Seminar

Venue at SISSA, Via Bonomea 265, room 128
Thursday 24 January at 14:00 hrs.

Mario COLLURA
University of Oxford, U.K.

'Tensor Network Methods for Probability Distribution Functions and
beyond...'

Abstract:
One of the paradigms of quantum mechanics is the statistical nature of
measurements: the result of measurements is indeed described by a
probability distribution function (PDF), and measuring the same observable
in identical systems will give different outcomes in accordance with this
distribution. The PDF carries very detailed information about the system,
going much beyond the simple average. Here I exploit the Matrix Product
Operator (MPO) representation of the Generating Functions to efficiently
perform local measurements in one-dimensional spin systems using Tensor
Network Methods, both in and out-of-equilibrium. Finally, inspired by such
formulation, I show some preliminary results connecting MPS with Neural
Network Quantum States.

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REMINDER - Condensed Matter and Statistical Physics Seminar

Venue at ICTP, Luigi Stasi Seminar Room, first floor, Leonardo building
Friday 25 January at 11:00 a.m.

Michele FILIPPONE
Theory of Quantum Matter, Physics, Univ. de Geneve, Switzerland

'Identical Suppression and Universality of the Hall Response in
Interacting Quantum Lattices'

Abstract:
The Hall effect is known as the voltage drop V perpendicular to the
current I and magnetic field B (perpendicular to I) measurable in electric
conductors. Its importance relies in the fact that, at weak field, the Hall
constant R_H= V/IB ~ -1/nq   and measures the charge q and density n
of charge carriers. Nevertheless, its calculation remains an open problem
in strongly correlated systems. We demonstrate the identical suppression
of the Hall response in quasi two-dimensional ballistic lattices, which is
robust  to large variations of magnetic field, Fermi level, temperature,
disorder and absence of particle-hole symmetry. This suppression is
unexpected and we show its relation to the topological properties of the
Fermi surface: namely its central charge. We show that this suppression
is commonly achieved in standard (Landauer) quantum transport settings
and we rely on DMRG to show that our results equally apply to strongly
interacting regimes [1].
Time permitting, I will also discuss how, in some particular cases,
interactions do not affect the Hall response at all, universally leading to
the non-interacting result R_H=-1/nq.

[1] Michele Filippone, Charles-Edouard Bardyn, Sebastian Greschner and
Thierry Giamarchi. To appear soon
[2] Sebastian Greschner, Michele Filippone and Thierry Giamarchi
arXiv:1809.10927