2022 Simons Collaboration on It from Qubit Annual Meeting

Date & Time

Patrick Hayden, Stanford University
Matthew Headrick, Brandeis University

Past Meetings:

Meeting Goals:
The 2022 Simons Collaboration on It from Qubit will be devoted to recent developments at the interface of fundamental physics and quantum information theory, spanning topics such as chaos and thermalization in many-body systems and their realization in quantum gravity; gravitational wormholes and their information-theoretic implications; calculable lower-dimensional models of quantum gravity; the entanglement structure of semi-classical states in quantum gravity; quantum error-correcting codes in quantum field theory and quantum gravity; complexity in field theory and gravity; the black-hole information puzzle; and quantum simulation and measurement-induced phase transitions.

  • Agendaplus--large


    9:30 AMTadashi Takayanagi | Pseudo Entropy and AdS(dS)/CFT
    10:30 AMBREAK
    11:00 AMHoracio Casini | Duality Defects, Entropic Order Parameters, and Noether's Theorem
    12:00 PMLUNCH
    1:00 PMLeonard Susskind | The Semiclassical Limit of De Sitter Space In (2+1)-Dimensions and the Double-Scaled Limit of SYK at Infinite Temperature
    2:00 PMBREAK
    2:30 PMPoster Session | IFQ Postdocs
    3:30 PMBREAK
    4:00 PMMark Van Raamsdonk | Cosmology via Holography


    9:30 AMDorit Aharonov | A Polynomial-Time Classical Algorithm for Noisy Random Circuit Sampling
    10:30 AMBREAK
    11:00 AMJohn Preskill | Learning Quantum Dynamics
    12:00 PMLUNCH
    1:00 PMPatrick Hayden | Entanglement, Complexity and Teleportation
  • Abstractsplus--large

    Dorit Aharonov
    Hebrew University

    A Polynomial-Time Classical Algorithm for Noisy Random Circuit Sampling

    The field of quantum computation heavily relies on the belief that quantum computation violates the extended Church Turing thesis, namely, that quantum many body systems cannot be simulated by classical ones with only polynomially growing overhead. What experimental evidence do we have for this assumption? Dorit Aharonov will overview the inherent difficulty in collecting such evidence. A major effort towards providing evidence for quantum advantage concentrates on “quantum supremacy” experiments via quantum random circuit sampling (RCS).

    These experiments can be modeled as sampling from a random quantum circuit where each gate is subject to a small amount of noise. Aharonov will give a polynomial time classical algorithm for sampling from the output distribution of a noisy random quantum circuit in the regime of anti-concentration to within inverse polynomial total variation distance. It should be noted that our algorithm is not practical in its current form, and does not address finite-size RCS based quantum supremacy experiments. Our result gives strong evidence that random circuit sampling (RCS) cannot be the basis of a scalable experimental violation of the extended Church-Turing thesis.

    Based on recent joint work with Xun Gao, Zeph Landau Yunchao Liu and Umesh Vazirani, arxiv: 2211.03999

    Horacio Casini
    CONICET, Instituto Balseiro

    Duality Defects, Entropic Order Parameters, and Noether’s Theorem

    Horacio Casini will review aspects of the existence of duality defects in quantum field theories. These appear in theories where the assignment of algebras to regions is not unique and give a precise way to understand completeness and the existence of generalized symmetries. Casini will show how entropic order parameters can be defined through the existence of the multiple algebras and the entropic certainty relation obeyed by dual order parameters. Casini will sketch the way different phases of QFT show up in terms of these order parameters. The interplay between duality defects and global symmetries leads to possible obstructions to strong forms of the Noether theorem and illuminates the reason behind known cases where this theorem does not apply. Several further consequences are suggested, such as the impossibility of charge-less electrodynamics.

    Patrick Hayden
    Stanford University

    Entanglement, Complexity and Teleportation

    The boundary realization of a quantum computer operating in the bulk of anti-de Sitter space is a distributed computation that implements the same computation without ever assembling all the input data in one place. Attempts to understand the power of those distributed computations led Alex May to prove that the complexity of the bulk computation can be bounded in terms of the boundary entanglement. In this talk, Patrick Hayden will describe a computationally efficient implementation of port-based teleportation, a protocol at the heart of those arguments, that leads to an exponential tightening of May’s bound.

    John Preskill
    California Institute of Technology

    Learning Quantum Dynamics

    When the It from Qubit collaboration launched in 2015, we were just beginning to appreciate the value of quantum information concepts like error correction and complexity for explorations of quantum gravity. Now these ideas are widely recognized as essential to the subject. What concepts from computer science will guide us in the next seven years? The answer is: I don’t know. But I think the IFQ community might benefit from learning about recent applications of learning theory to quantum systems, so I will describe some of these developments. I won’t explain how these ideas will be useful in quantum gravity — that’s for you to figure out. The talk draws from a recent paper with Robert Huang and Sitan Chen (https://arxiv.org/abs/2210.14894) and earlier papers referenced there.

    Leonard Susskind
    Stanford University

    The Semiclassical Limit of De Sitter Space In (2+1)-Dimensions and the Double-Scaled Limit of SYK at Infinite Temperature

    Leonard Susskind will explain the four important length scales that occur in dS(2+1) — the cosmic, Planck, micro, and string scales,  and why they are dual to the SYK scales Lc  =  1/J, Lp = 1/JN, Lc = 1/JN(1/2), Ls = 1/(Jq) in the semi-classical limit. The consistency of these correspondences is further evidence for the conjectured duality between de Sitter space in 3-dimensions and the double-scaled limit of SYK at infinite temperature.

    Tadashi Takayanagi
    Kyoto University

    Pseudo Entropy and AdS(dS)/CFT

    Pseudo entropy is a generalization of entanglement entropy such that it depends on both an initial and final state. It has a clear gravity dual via the AdS/CFT, namely the minimal surface area in a Euclidean time-dependent AdS background. In this talk, Tadashi Takayanagi will explain the definition and basic properties of pseudo entropy as well as discuss recent applications of pseudo entropy to quantum phase transition and to dS/CFT.

    Mark Van Raamsdonk
    University of British Columbia

    Cosmology via Holography

    Mark Van Raamsdonk will describe how the standard tools of holography might be used to define microscopic models of big-bang cosmology.  Van Raamsdonk will consider models where a bubble of the cosmological spacetime is embedded in an asymptotically AdS spacetime, and models where an asymptotically AdS Euclidean spacetime obtained by analytically continuing the cosmological spacetime is described via a Euclidean CFT construction. While the effective field theories we consider have negative cosmological constant, they can describe realistic accelerating cosmologies via the positive potential energy of time-dependent scalar fields.

  • Princeton/IAS IFQ Workshop, December 5-7 plus--large

    Separate Registration Required

    Program Contact: Lisa Fleischer, lisa@ias.edu


  • Participation & Fundingplus--large

    Participation in the meeting falls into the following four categories. An individual’s participation category is communicated via their letter of invitation.

    Group A – PIs and Speakers
    The foundation will arrange and pay for all air and train travel to the conference as well as hotel accommodations and reimbursement of local expenses.

    Group B – Out-of-town Participants
    The foundation will arrange and pay for all air and train travel to the conference as well as hotel accommodations and reimbursement of local expenses.

    Group C – Local Participants
    Individuals in Group C will not receive financial support, but are encouraged to enjoy all conference-hosted meals.

    Group D – Remote Participants
    Individuals in Group D will participate in the meeting remotely. Please register at the link above and a remote participation link will be sent to you approximately two weeks prior to the meeting.

  • Travel & Hotelplus--large

    Air and Train
    The foundation will arrange and pay for all air and train travel to the conference for those in Groups A and B. Please provide your travel specifications by clicking the registration link above. If you are unsure of your group, please refer to your invitation sent via email.

    Personal Car
    For participants in Groups A & B driving to Manhattan, The James NoMad Hotel offers valet parking. Please note there are no in-and-out privileges when using the hotel’s garage, therefore it is encouraged that participants walk or take public transportation to the Simons Foundation.

    Participants in Groups A & B who require accommodations are hosted by the foundation for a maximum of three nights at The James NoMad Hotel. Any additional nights are at the attendee’s own expense. To arrange accommodations, please register at the link above.

    The James NoMad Hotel
    22 E 29th St
    New York, NY 10016
    (between 28th and 29th Streets)

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  • COVID-19 Policyplus--large

    ALL in-person meeting attendees must be vaccinated against the COVID-19 and wear a mask when not eating or drinking.

  • Reimbursementplus--large

    Individuals in Groups A & B will be reimbursed for meals not hosted by the Simons Foundation as well as local expenses, including ground transportation. Additional information in this regard will be emailed on the final day of the meeting.

  • Contactsplus--large

    Registration and Travel Assistance
    Ovation Travel Group
    Phone: (917) 408-8384 (24-Hours)

    Meeting Questions and Assistance
    Meghan Fazzi
    Manager, Events and Administration, MPS, Simons Foundation
    (212) 524-6080

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