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Quantum World 2 Seminar

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Every Thursday, BME FA Seminar room

Upcoming sessions:


April 25, 2025, Thursday, 8.30
Paper: I. Duque, P. Strasberg: Toy Model Challenging Prevailing Definitions of Classicality link
By János Asbóth


May 8, 2025, Thursday, 8.30
Title: Locality and subsystems from the spectrum
Abstract: The minimal ingredients to describe a quantum system are a Hamiltonian, an initial state, and a preferred tensor product structure that encodes a decomposition into subsystems. I will discuss a top-down approach in which the decomposition into subsystems emerge from the spectrum of the whole system. This approach has been referred to as quantum mereology. In practice, it is interesting to understand whether a given Hamiltonian is compatible with some given tensor product structure. Addressing this question allows us to suggest a possible mechanism for the emergence of locality and subsystems from quantum mechanics itself.
Discussion of papers link and link
By Nicolas Loizeau (online)


Previous sessions:


February 6, 2025, Thursday, 10.00
Short Paper: J. Finkelstein: Definition of decoherence link
Longer Paper: C. Riedel, W. Zurek, M. Zwolak: Objective past of a quantum universe: Redundant records of consistent histories link
By Tibor Rakovszky


February 13, 2025, Thursday, 8.30
Paper: C. Riedel, W. Zurek, M. Zwolak: Objective past of a quantum universe: Redundant records of consistent histories link
Short comment: L. Diósi: Anomalies of Weakened Decoherence Criteria for Quantum Histories link
By Tibor Rakovszky


February 20, 2025, Thursday, 8.30
Paper: P. Strasberg, J. Schindler: First Principles Numerical Demonstration of Emergent Decoherent Histories link
By Daniel Varjas


February 27, 2025, Thursday, 8.30
Paper: P. Strasberg, J. Schindler: First Principles Numerical Demonstration of Emergent Decoherent Histories link
By Daniel Varjas


March 6, 2025, Thursday, 8.30
Paper: part of K. Hornberger: Introduction to decoherence theory link
Notes: Pointer states link
By Győző Egri

Paper: P. Strasberg, J. Schindler: Shearing Off the Tree: Emerging Branch Structure and Born’s Rule in an Equilibrated Multiverse link
By János Asbóth


March 13, 2025, Thursday, 8.30
Paper: N. Loizeau, F. Morone and D. Sels: Unveiling Order from Chaos by approximate 2-localization of random matrices link
By István Csépányi


March 20, 2025, Thursday, 8.30
Paper: N. Loizeau, F. Morone and D. Sels: Quantum mereology and subsystems from the spectrum link
By Márton Kormos


March 27, 2025, Thursday, 8.30
Paper: J. Wang, P. Strasberg: Decoherence of Histories: Chaotic Versus Integrable Systems link
By Solomon Brhanu Samuel


April 3, 2025, Thursday, 8.30
Title: Decoherent histories and a quantitative understanding of the many worlds interpretation
Abstract: This talk overviews and advertises the decoherent histories framework as a useful tool to make sense of a unitarily evolving Universe. In particular, observers can find records about past events if and only if the associated quantum histories are decoherent. I then review three recent quantitative insights about decoherent histories. First, I show that decoherence arises exponentially fast as a function of system size for slow and coarse observables. Second, this result only holds for chaotic systems, whereas integrable systems show a very different scaling. Third, I give preliminary insights into the structure of decoherence that arises for very long histories.
Discussion of papers link, link and link
By Philipp Strasberg (online)


April 10, 2025, Thursday, 8.30
Paper: L. Vaidman: Role of potentials in the Aharonov-Bohm effect link
Notes: Aharonov-Bohm link
By Győző Egri


April 17, 2025, Thursday, 8.30
Paper: P. Pearle, A. Rizzi: Quantized vector potential and alternative views of the magnetic Aharonov-Bohm phase shift link
Original idea: L. Vaidman: Role of potentials in the Aharonov-Bohm effect link
Notes: Aharonov-Bohm link
By Győző Egri


List of interesting papers:


Add new papers here


C. Overstreet, P. Asenbaum, J. Curti, M. Kim, M. Kasevich: Observation of a gravitational Aharonov-Bohm effect link


W. Zurek: Consensus About Classical Reality in a Quantum Universe link


D. Carney, M. Karydas, T. Scharnhorst, R. Singh, J. Taylor: On the quantum mechanics of entropic forces link


J. Taylor, P. McCulloh: Wavefunction branching: when you can’t tell pure states from mixed states link


Adil et al: A Search for Classical Subsystems in Quantum Worlds link


R. Blume-Kohout, W. Zurek: A Simple Example of “Quantum Darwinism”: Redundant Information Storage in Many-Spin Environments link


F. Brandao, M. Piani, P. Horodecki: Generic emergence of classical features in quantum Darwinism link


R. Blume-Kohout, H. Ng, D. Poulin, L. Viola: Information-preserving structures: A general framework for quantum zero-error information link


J. Cotler, G. Penington, D. Ranard: Locality from the spectrum link


C-J. Cao: From Quantum Codes to Gravity: A Journey of Gravitizing Quantum Mechanics link


S. Carroll, A. Singh: Quantum mereology: Factorizing Hilbert space into subsystems with quasiclassical dynamics link


E. Doucet, S. Deffner: Compatibility of quantum measurements and the emergence of classical objectivity link


B. Ferté, X. Cao: Solvable model of quantum Darwinism-encoding transitions link


X-L Qi, D. Ranard: Emergent classicality in general multipartite states and channels link


G. Lindblad: Decoherence properties of finite quantum systems link


G. Higgens, A. Di Biaggio, M. Christodoulou: A truly relativistic gravity mediated entanglement protocol using superpositions of rotational energies link


L. Diósi: A healthier stochastic semiclassical gravity: world without Schrödinger cats link


A. Bassi, K. Lochan, S. Satin, T. P. Singh, H. Ulbricht: Models of wave-function collapse, underlying theories, and experimental tests link


D. Schmid, K. Ried, R. W. Spekkens: Why initial system-environment correlations do not imply the failure of complete positivity: A causal perspective link


F. Giacomini, E. Castro-Ruiz, C. Brukner: Quantum mechanics and the covariance of physical laws in quantum reference frames link