1. Sorry for my mistake about the day in Netta's talk on black holes.
2. There is another conference this week, on random quantum circuits
https://www.pks.mpg.de/dcurqc20/program/
3. See below for a talk by Soonwon on Mon, Oct 5.
---------- Forwarded message ---------
From: Lesley Keaney <lkeaney(a)mit.edu>
Date: Tue, Sep 29, 2020 at 8:54 AM
Subject: [CMT Seminar] Chez Pierre seminar-Monday, October 5, 2020 (via Zoom)
To: chezpierre <chezpierre(a)mit.edu>du>, cmt_seminar <cmt_seminar(a)mit.edu>
Hello everyone,
The next Chez Pierre Seminar for the Fall 2020 semester will be held
on Monday, October 5, 2020 at 12:00pm noon EDT.
The seminar will be broadcast via password protected Zoom link. The
details are listed below.
Soonwon Choi – Massachusetts Institute of Technology
“Symmetry and information flow in quantum circuits with measurements”
We will discuss novel quantum phases and phase transitions that emerge
in the dynamics of quantum circuits and exhibit distinct modes of
information flow. We consider a quantum system undergoing time
evolution generated by random unitary gates which are occasionally
interrupted by local measurements. It was previously found that such
evolution leads to a phase transition in the entanglement of the
wavefunction: at steady state it is characterized by volume law
entanglement for small measurement rate, while it is an area law above
a threshold rate. We investigate this phase transition by mapping the
quantum dynamics into classical statistical mechanics models in
equilibrium. Furthermore, we show that more phases are possible if we
impose symmetries on the dynamics. To identify the phases, we develop
a mapping between the dynamics in a broad class of quantum circuits to
the ground states of effective spin Hamiltonians, which possess a
higher symmetry than the original circuit. The different ground state
phases admitted by the higher symmetry correspond to distinct patterns
of information flow and scrambling in the circuit dynamics. We
illustrate these ideas with two examples: (i) a quantum circuit with
Z_2 symmetry resulting in non-abelian D_4 symmetry in an effective
Hamiltonian and (ii) a quadratic fermionic circuit leading to U(1)
symmetry. The latter exhibits Kosterlitz–Thouless transition in 1D
between a critical phase with log(L) entanglement and "trivial" area
law phases. Our work is a first step toward the classification of
information flow in generic quantum circuits with symmetries.
Talk: 12:00pm noon
Date: Monday, October 5, 2020
Broadcast via: Zoom (details are listed below)
Host: Senthil Todadri
Time: October 5, 2020 12:00pm Eastern Time (US and Canada)
Join Zoom Meeting:
https://mit.zoom.us/j/98108729602?pwd=QXpCSkdBRVJWUkNFSWlOcnovMUFEZz09
Password: 799417
One tap mobile
+16465588656,,98108729602# US (New York)
+16699006833,,98108729602# US (San Jose)
Meeting ID: 981 0872 9602
US : +1 646 558 8656 or +1 669 900 6833
International Numbers:
https://mit.zoom.us/u/adC66pLaYX
Join by SIP
98108729602(a)zoomcrc.com
Join by Skype for Business
https://mit.zoom.us/skype/98108729602Chez Pierre seminars are usually
scheduled for Mondays at 12:00pm noon EDT. Seminar speakers, titles
and abstracts will be posted on the Chez Pierre seminar website:
http://web.mit.edu/physics/cmt/chezp.html.
Thank you,
Lesley
Lesley Keaney
Administrative Assistant
Condensed Matter Theory Group
MIT Department of Physics
Room 6C-339
Cambridge, MA 02139
617.253.4878 (phone); 617.253.2562 (fax)
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