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BEGIN:VEVENT
SUMMARY:Samuel Garratt (Oxford University)
DTSTART:20200917T150000Z
DTEND:20200917T160000Z
DTSTAMP:20260422T225926Z
UID:QChaos2020/1
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QChaos2020/1
 /">Many-body quantum chaos and local pairing of Feynman histories</a>\nby 
 Samuel Garratt (Oxford University) as part of Quantum Chaos 2020 Seminars\
 n\nAbstract: TBA\n
LOCATION:https://researchseminars.org/talk/QChaos2020/1/
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BEGIN:VEVENT
SUMMARY:Adolfo del Campo (Donostia International Physics Center)
DTSTART:20200924T150000Z
DTEND:20200924T160000Z
DTSTAMP:20260422T225926Z
UID:QChaos2020/2
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QChaos2020/2
 /">Quantum Chaos versus Decoherence</a>\nby Adolfo del Campo (Donostia Int
 ernational Physics Center) as part of Quantum Chaos 2020 Seminars\n\n\nAbs
 tract\nQuantum chaos imposes universal spectral signatures that govern the
  thermofield dynamics of a many-body system in isolation. The fidelity bet
 ween the initial and time-evolving thermofield double states exhibits as a
  function of time a decay\, dip\, ramp and plateau. Sources of decoherence
  give rise to a non-unitary evolution and result in information loss. Ener
 gy dephasing gradually suppresses quantum noise fluctuations and the dip a
 ssociated with spectral correlations. Decoherence further delays the appea
 rance of the dip and shortens the span of the linear ramp associated with 
 chaotic behavior. The interplay between signatures of quantum chaos and in
 formation loss is determined by the competition among the decoherence\, di
 p and plateau characteristic times\, as demonstrated in the stochastic Sac
 hdev-Ye-Kitaev model.\n
LOCATION:https://researchseminars.org/talk/QChaos2020/2/
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BEGIN:VEVENT
SUMMARY:Anabelle Bohrdt (Technical University Munich)
DTSTART:20201001T150000Z
DTEND:20201001T160000Z
DTSTAMP:20260422T225926Z
UID:QChaos2020/3
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QChaos2020/3
 /">Probing dynamics in quantum simulators</a>\nby Anabelle Bohrdt (Technic
 al University Munich) as part of Quantum Chaos 2020 Seminars\n\n\nAbstract
 \nIn this talk I will discuss new possibilities to probe the dynamics of q
 uantum many-body systems\, in particular the Bose-Hubbard model with and w
 ithout disorder. \nOut-of-time-ordered (OTO) correlation functions have be
 en proposed to describe the distribution or “scrambling” of informatio
 n across a quantum state. We investigate both time-ordered and OTO correla
 tion functions in the non-integrable\, one-dimensional Bose-Hubbard model 
 at high temperatures where well-defined quasiparticles cease to exist. We 
 propose an interferometric scheme to approach the challenge of measuring t
 hese correlation functions in real space and time. Performing numerical si
 mulations based on matrix product operators\, we observe a linear light-co
 ne spreading of quantum information in the OTO correlators. In contrast wi
 th the fast spreading of information\, the thermalization of the system ta
 kes parametrically longer due to the slow diffusion of conserved quantitie
 s. Adding strong disorder can inhibit thermalization\, leading to a many-b
 ody localized (MBL) phase. Beyond the absence of transport\, the MBL phase
  has distinctive signatures\, such as slow dephasing and logarithmic entan
 glement growth. We experimentally probe these signatures in a system of co
 upled superconducting qubits.\n
LOCATION:https://researchseminars.org/talk/QChaos2020/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Lennart Dabelow (Bielefeld University)
DTSTART:20201008T150000Z
DTEND:20201008T160000Z
DTSTAMP:20260422T225926Z
UID:QChaos2020/4
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QChaos2020/4
 /">Typicality approach to perturbed quantum many-body relaxation</a>\nby L
 ennart Dabelow (Bielefeld University) as part of Quantum Chaos 2020 Semina
 rs\n\n\nAbstract\nWe develop an analytical prediction for the relaxation o
 f isolated many-body quantum systems subject to weak-to-moderate perturbat
 ions. Provided that the unperturbed behavior is known\, we employ a typica
 lity approach modeling the essential characteristics of the perturbation o
 perator to describe the time evolution of expectation values in the pertur
 bed system. In particular\, the prediction identifies two decisive paramet
 ers of the perturbation: its overall strength and its energy range or band
  width. The theory provides a unified framework for such diverse phenomena
  as prethermalization\, quantum quenches\, or the relaxation of system-bat
 h compounds. We demonstrate its wide applicability by comparison with vari
 ous experimental and numerical examples.\n
LOCATION:https://researchseminars.org/talk/QChaos2020/4/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Daniel Ranard (Stanford University)
DTSTART:20201015T150000Z
DTEND:20201015T160000Z
DTSTAMP:20260422T225926Z
UID:QChaos2020/5
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QChaos2020/5
 /">Bounding the spread of quantum information\, and emergent classicality 
 in dynamics of large systems</a>\nby Daniel Ranard (Stanford University) a
 s part of Quantum Chaos 2020 Seminars\n\n\nAbstract\nHow can information a
 bout a single subsystem spread through a many-body environment?  We show t
 hat whenever a subsystem interacts with an environment\, for almost everyw
 here in the environment\, any locally accessible information about the sub
 system must be approximately classical\, i.e. obtainable from some fixed m
 easurement. The result strengthens the earlier result of arXiv:1310.8640. 
  It may also be seen as a new consequence of the principles of no-cloning 
 or monogamy of entanglement. The proof offers a constructive optimization 
 procedure for determining the effective "measurement" on the subsystem ind
 uced by the dynamics. Alternatively\, under channel-state duality\, these 
 results characterize the marginals of multipartite states.  Talk based pri
 marily on arXiv:2001.01507.\n
LOCATION:https://researchseminars.org/talk/QChaos2020/5/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shreya Vardhan (MIT)
DTSTART:20201022T150000Z
DTEND:20201022T160000Z
DTSTAMP:20260422T225926Z
UID:QChaos2020/6
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QChaos2020/6
 /">A universal approximation for entanglement entropies of equilibrated pu
 re states</a>\nby Shreya Vardhan (MIT) as part of Quantum Chaos 2020 Semin
 ars\n\n\nAbstract\nWhen a pure state in a non-integrable quantum many-body
  system is evolved to late times\, we expect it to thermalize—that is\, 
 we expect its macroscopic properties to resemble those of an equilibrium d
 ensity matrix. However\, the entanglement entropies of such a state must o
 bey certain constraints coming from unitarity\, which are not obeyed by an
  equilibrium density matrix. In this talk\, I will explain an approximatio
 n method that leads to a simple universal expression for the entanglement 
 entropies of an equilibrated pure state in any quantum many-body system. T
 his expression is independent of the details of the initial state and henc
 e reflects thermalization\, while also being manifestly consistent with un
 itarity. I will also discuss how this method can be applied to equilibrate
 d pure states in gravitational systems\, such as those involving black hol
 es\, where it can be used to address the information loss paradox of Hawki
 ng.\n
LOCATION:https://researchseminars.org/talk/QChaos2020/6/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Vedika Khemani (Stanford University)
DTSTART:20201029T180000Z
DTEND:20201029T190000Z
DTSTAMP:20260422T225926Z
UID:QChaos2020/7
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QChaos2020/7
 /">Entanglement dynamics in non-unitary circuits</a>\nby Vedika Khemani (S
 tanford University) as part of Quantum Chaos 2020 Seminars\n\n\nAbstract\n
 Recent work has shown that unitary circuits subject to repeated projective
  measurements can undergo an entanglement transition as a function of the 
 measurement rate. This transition is generally understood in terms of a co
 mpetition between the scrambling effects of unitary dynamics and the disen
 tangling effects of measurements. I will discuss how\, surprisingly\, enta
 nglement transitions are possible even in the absence of unitary dynamics 
 in “measurement only” models. I will talk about the entanglement phase
  diagrams in these models\, and also present results on measures of locali
 ty under non-unitary dynamics. Finally\, I will discuss a recent proposal 
 to measure entanglement without issues of postselection in a class of non-
 unitary circuits using ideas of spacetime duality.\n
LOCATION:https://researchseminars.org/talk/QChaos2020/7/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Bin Yan (Los Alamos National Laboratory)
DTSTART:20201105T160000Z
DTEND:20201105T170000Z
DTSTAMP:20260422T225926Z
UID:QChaos2020/8
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/QChaos2020/8
 /">The Quantum Zoo of Butterflies</a>\nby Bin Yan (Los Alamos National Lab
 oratory) as part of Quantum Chaos 2020 Seminars\n\n\nAbstract\nClassical c
 haotic dynamics exhibit extreme sensitivity to initial conditions --  know
 n as the butterfly effect. The problem in quantum mechanics\, however\, is
  much more subtle. Conventional approaches usually address quantum chaos i
 n the energy domain\, e.g.\, spectral correlations. Recently developments 
 invented different diagnostics to reveal the quantum butterfly effect in t
 he time domain. The quantum butterfly effect has a much richer structure t
 han its classical counterpart. In this talk\, I will tell a coherent story
  and introduce various types of butterflies in the quantum world: The famo
 us Lorenz-Butterfly with circuit complexity\; a Bradbury-Butterfly known a
 s a novel correlator\, the out-of-time correlator\; and an Anti-Butterfly 
 which can heal damaged information from the past.\n
LOCATION:https://researchseminars.org/talk/QChaos2020/8/
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