1 December 2025
Paper: J. Riedel: Wavefunction branches demand a definition link
By Jess Riedel (online)
8 December 2025
Title: Resurgence theory: from perturbation theory to non-perturbative phenomena I
Paper 1: R. C. Helling: How I Stopped Worrying and Learned to Love QFT link, section 1 and 2
Paper 2: M. Serone: Lectures on Resurgence in Integrable Field Theories link, section 1 and 2
Abstract It is well known that quantum mechanical and quantum field
theoretical perturbation theory leads to an asymptotic expansion, which
is generally divergent and used in practice only as an approximation
based on its first few terms. Resurgence theory tells us how the
large-order behaviour of this series encodes information about the
physics far beyond the perturbative regime, and how this knowledge can
be extracted to extrapolate towards the non-perturbative value of the
expanded quantity, at least in principle. Although at present this
program can be realized and tested only on certain toy models of QFT, it
is speculated that it might eventually help to provide a continuum
definition of quantum field theories, or to improve the calculated
values of quantities governed by non-perturbative effects in low-energy
quantum chromodynamics.
By István Vona
15 December 2025
Title: Resurgence theory: from perturbation theory to non-perturbative phenomena II
Paper 1: R. C. Helling: How I Stopped Worrying and Learned to Love QFT link (section 1 and 2)
Paper 2: M. Serone: Lectures on Resurgence in Integrable Field Theories link (section 1 and 2)
By István Vona
8 September 2025
Paper: C. Emary, N. Lambert, F. Nori: Leggett–Garg inequalities link
By Márton Kormos
15 September 2025
Paper: F. Pastawski, B. Yoshida, D. Harlow, J. Preskill: Holographic quantum error-correcting codes: toy models for the bulk/boundary correspondence link
By Péter Lévay
29 September 2025
Paper: A. Bassi, K. Lochan, S. Satin, T. P. Singh, H. Ulbricht: Models of wave-function collapse, underlying theories, and experimental tests link part II
By Máté Lencsés
6 October 2025
Paper: A. Tilloy: General quantum-classical dynamics as measurement based feedback link
By Antoine Tilloy (online)
13 October 2025
Paper: J. Taylor, P. McCulloh: Wavefunction branching: when you can’t tell pure states from mixed states link
By Tibor Rakovszky
20 October 2025
Paper: A. Bassi, K. Lochan, S. Satin, T. P. Singh, H. Ulbricht: Models of wave-function collapse, underlying theories, and experimental tests link part III/B
By Máté Lencsés
27 October 2025
Paper: JM. A. Allen, J. Barrett, D. C. Horsman, C. M. Lee, R. W. Spekkens: Quantum Common Causes and Quantum Causal Models link
By Szilárd Szalay
3 November 2025
Paper: N. Ormrod, J. Barrett: Quantum influences and event relativity link
By Nicholas Ormrod (online)
10 November 2025
Paper: J. Taylor, P. McCulloh: Wavefunction branching: when you can’t tell pure states from mixed states, continued from section VI link
Title: Finding Non-Interfering Decompositions in Matrix Product States
Abstract: We present practical algorithms for finding non-interfering "branch" decompositions in Matrix Product States (MPS). It establishes conditions, such as block-diagonality in tensor structure, sufficient for non-interference. Novel iterative and gradient-based algorithms are developed and tested to find these decompositions. Finally, a time evolution protocol is introduced that leverages these decompositions and samples over the branches, demonstrating advantages over standard MPS truncation methods for simulating quantum dynamics.
By Jordan Taylor (online)
17 November 2025
Paper: D. Schmid, K. Ried, R. W. Spekkens: Why initial system-environment correlations do not imply the failure of complete positivity: A causal perspective link
By David Schmid (online)
24 November 2025
Title: Approximately decoherent histories
Abstract: The decoherent histories condition is in one-to-one correspondence with records about past events in an isolated quantum system and as such is essential to study the many worlds (and related) interpretations. Alas, this is only true for exactly decoherent histories, but in reality interesting non-trivial histories are only approximately decoherent. In this talk we delve deeper into the topic of approximate decoherence assuming a Hilbert space of finite dimension D. We reveal that there are >> D many approximately decoherent histories, whereas observers inside the Multiverse can only reliably distinguish << D many records. To investigate the latter we define the "selflocation problem" as a coherent version of quantum state discrimination. Eventually, this conundrum leads to a "branch selection problem". If time permits we will also discuss the structure of decoherence between different branches of the Multiverse based on a numerical example.
By Philipp Strasberg (online)
Add new papers here
B. Ferté, D. Farci, X. Cao: Decoherent histories with(out) objectivity in a (broken) apparatus 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
R. Blume-Kohout, W. Zurek: A Simple Example of “Quantum Darwinism”: Redundant Information Storage in Many-Spin Environments 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
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G. Higgens, A. Di Biagio, 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
F. Giacomini, E. Castro-Ruiz, C. Brukner: Quantum mechanics and the covariance of physical laws in quantum reference frames link
A. Touil, F. Anza, S. Deffner, JP Crutchfield: Branching States as The Emergent Structure of a Quantum Universe link
P. Figueroa-Romero, K. Modi, and FA. Pollock: Almost Markovian processes from closed dynamics link