IFQ-ExU joint mini workshop: Extreme Universe from Qubits
December 16 th -18th, 2021
Organizers: Yasuhiro Sekino (Takushoku), Tadashi Takayanagi (Kyoto) ,Tomonori Ugajin (Kyoto)
Embedded Files
Invited speakers
Matthew Headrick (Brandeis)
Patrick Hayden (Stanford)
Veronika Hubeny (UC. Davis)
Norihiro Iizuka (Osaka)
Yoshifumi Nakata (Tokyo)
Edgar Shaghoulian (Penn)
Douglas Stanford (Stanford)
Beni Yoshida (Perimeter)
Program
This workshop will be held online (using zoom)
Dec 16th (Thu)
Evening
22:50-23:00:(JST) :Opening (Video)
23:00-24:00 (JST)
Matthew Headrick: Covariant bit threads, minimax surfaces, and entropy inequalities (Video)
The HRT covariant holographic entropy formula admits two equivalent formulations, the original extremal surface version and Wall’s maximin version. Having these two versions has proven invaluable for understanding important properties of the HRT surface, the entanglement wedge, and the entropy. On the general principle that more is better, in this talk I will introduce and explore eight more equivalent versions of the HRT formula. The new formulations involve threads of various kinds, minimax surfaces, and other constructs. Focusing on the minimax formula, I will then explain how to use it to prove entropy inequalites beyond those provable using maximin.
Dec 17th (Fri)
Morning (Video)
9:00-10:00 (JST)
Douglas Stanford:Subleading Weingartens
Abstract: Averages over large unitary matrices contain small terms that are important consequences of unitarity. We will explore the semiclassical origin of these terms in two systems: JT gravity and Brownian SYK.
10:00-11:00 (JST)
Veronika Hubeny : Holographic Entropy Cone from Marginal Independence
11:00-12:00 (JST)
Norihiro Iizuka: Defining entanglement without tensor factoring: a Euclidean hourglass prescription
Abstract: We consider entanglement across a planar boundary in flat space. Entanglement entropy is usually thought of as the von Neumann entropy of a reduced density matrix, but it can also be thought of as half the von Neumann entropy of a product of reduced density matrices on the left and right. The latter form allows a natural regulator in which two cones are smoothed into a Euclidean hourglass geometry. Since there is no need to tensor-factor the Hilbert space, the regulated entropy is manifestly gauge-invariant and has a manifest state-counting interpretation. We explore this prescription for scalar fields, where the entropy is insensitive to a non-minimal coupling, and for Maxwell fields, which have the same entropy as d-2 scalars.
22:00 -23:00 (JST)
Edgar Shaghoulian : The central dogma and cosmological horizons
23:00 -24:00 (JST)
Beni Yoshida : Decoding monitored quantum circuits (and black holes)
Abstract: Given an output wavefunction of a monitored quantum circuit consisting of both unitary gates and projective measurements, we ask whether two complementary subsystems are entangled or not. For Clifford circuits, we find that this question can be mapped to a certain classical error-correction problem where various entanglement measures can be explicitly computed from the recoverability. The dual classical code is constructed from spacetime patterns of out-of-time ordered correlation functions among local operators and measured Pauli operators in the past, suggesting that the volume-law entanglement in a monitored circuit emerges from quantum information scrambling, namely the growth of local operators. We also present a method of verifying quantum entanglement by providing a simple deterministic entanglement distillation algorithm, which can be interpreted as decoding of the dual classical code. Applications of our framework to various physical questions, including non-Clifford systems, are discussed as well. Namely, we argue that the entanglement structure of a monitored quantum circuit in the volume-law phase is largely independent of the initial states and past measurement outcomes except recent ones, due to the decoupling phenomena from scrambling dynamics, up to a certain polynomial length scale which can be identified as the code distance of the circuit. We also derive a general relation between the code distance and the sub-leading contribution to the volume-law entanglement entropy. Applications of these results to black hole physics are discussed as well.
Dec 18th (Sat)
Morning (Video)
9:00-10:00 (JST)
Patrick Hayden: A canonical definition of energy in strongly interacting open quantum systems (provisional title)
10:00-11:00 (JST)
Yoshifumi Nakata: Decoding the Hayden-Preskill protocol: from classical to quantum information
Registration
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