[Aspuru-Guzik Group List] [qip] more talks

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) _______________________________________________ CMT_seminar mailing list CMT_seminar(a)mit.edu http://mailman.mit.edu/mailman/listinfo/cmt_seminar _______________________________________________ qip mailing list qip(a)mit.edu http://mailman.mit.edu/mailman/listinfo/qip