Fri - 10/06/23

There is no new related paper today

There is no new related paper today

Thu - 10/05/23

What if Quantum Gravity is “just’’ Quantum Information Theory?

  • Authors: Aron C. Wall
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
  • Arxiv link: https://arxiv.org/abs/2310.02958
  • Abstract I suggest the possibility that holographic quantum gravity is, in some sense, equivalent to quantum information theory. Some radical implications would follow. First, the theory of quantum gravity should have no adjustable coupling constants, similar to string theory. Thus, all complete bulk theories of quantum gravity are dual to each other. By setting up an appropriately entangled state, it should be possible to find wormholes connecting any two quantum gravity theories (e.g. string theory and loop quantum gravity). Secondly, if we represent space at one time as a tensor network, then dynamics is automatically encoded via gauge-equivalent descriptions of the boundary state. This would appear to imply, contrary to semiclassical expectations, that a closed universe should have only one state.

There is no new related paper today

  1. [2310.02338] - Is a Quantum Gravity Era Necessary? - Bogdan Veklych

Wed - 10/04/23

Remnant loop quantum black holes

  • Authors: H. A. Borges, I. P. R. Baranov, F. C. Sobrinho, S. Carneiro
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
  • Arxiv link: https://arxiv.org/abs/2310.01560
  • Abstract Polymer models inspired by Loop Quantum Gravity (LQG) have been used to describe non-singular quantum black holes with spherical symmetry, with the classical singularity replaced by a transition from a black hole to a white hole. A recent model, with a single polymerisation parameter, leads to a symmetric transition with same mass for the black and white phases, and to an asymptotically flat exterior metric. The radius of the transition surface is, however, not fixed, increasing with the mass. Following similar procedures, in a previous paper we have fixed that radius by identifying the minimal area on the transition surface with the area gap of LQG. This allowed to find a dependence of the polymerisation parameter on the black hole mass, with the former increasing as the latter decreases. It also permitted to extend the model to Planck scale black holes, with quantum fluctuations remaining small at the horizon. In the present paper we extend this analysis to charged black holes, showing that the Cauchy horizon lies beyond of the transition surface. We also show the existence of limiting states with zero surface gravity, the lightest one with $Q = 0$ and $m = \sqrt{2}/4$, and the heaviest with $Q = m = \sqrt{2}/2$. Using our solutions to approximate quasi-steady horizons, we show that Hawking evaporation leads asymptotically to these extremal states, leaving remnant black holes of Planck size.

Symmetry TFT for Subsystem Symmetry

  • Authors: Weiguang Cao, Qiang Jia
  • Subjects: High Energy Physics - Theory (hep-th); Strongly Correlated Electrons (cond-mat.str-el)
  • Arxiv link: https://arxiv.org/abs/2310.01474
  • Abstract We generalize the idea of symmetry topological field theory (SymTFT) for subsystem symmetry. We propose the 2-foliated BF theory with level $N$ in $(3+1)$d as subsystem SymTFT for subsystem $\mathbb Z_N$ symmetry in $(2+1)$d. Focusing on $N=2$, we investigate various topological boundaries. The subsystem Kramers-Wannier and Jordan-Wigner dualities can be viewed as boundary transformations of the subsystem SymTFT and are included in a larger duality web from the subsystem $SL(2,\mathbb Z_2)$ symmetry of the bulk foliated BF theory. Finally, we construct the condensation defects and twist defects of the subsystem $SL(2,\mathbb Z_2)$ transformation, from which the fusion rule of subsystem non-invertible operators can be recovered.

Algebras and Hilbert spaces from gravitational path integrals: Understanding Ryu-Takayanagi/HRT as entropy without invoking holography

  • Authors: Eugenia Colafranceschi, Xi Dong, Donald Marolf, Zhencheng Wang
  • Subjects: High Energy Physics - Theory (hep-th); General Relativity and Quantum Cosmology (gr-qc)
  • Arxiv link: https://arxiv.org/abs/2310.02189
  • Abstract Recent works by Chandrasekaran, Penington, and Witten have shown in various special contexts that the quantum-corrected Ryu-Takayanagi (RT) entropy (or its covariant Hubeny-Rangamani-Takayanagi (HRT) generalization) can be understood as computing an entropy on an algebra of bulk observables. These arguments do not rely on the existence of a holographic dual field theory. We show that analogous-but-stronger results hold in any UV-completion of asymptotically anti-de Sitter quantum gravity with a Euclidean path integral satisfying a simple and familiar set of axioms. We consider a quantum context in which a standard Lorentz-signature classical bulk limit would have Cauchy slices with asymptotic boundaries $B_L \sqcup B_R$ where both $B_L$ and $B_R$ are compact manifolds without boundary. Our main result is then that (the UV-completion of) the quantum gravity path integral defines type I von Neumann algebras ${\cal A}^{B_L}L$, ${\cal A}^{B_R}{R}$ of observables acting respectively at $B_L$, $B_R$ such that ${\cal A}^{B_L}L$, ${\cal A}^{B_R}{R}$ are commutants. The path integral also defines entropies on ${\cal A}^{B_L}_L, {\cal A}^{B_R}_R$. Positivity of the Hilbert space inner product then turns out to require the entropy of any projection operator to be quantized in the form $\ln N$ for some $N \in {\mathbb Z}^+$ (unless it is infinite). As a result, our entropies can be written in terms of standard density matrices and standard Hilbert space traces. Furthermore, in appropriate semiclassical limits our entropies are computed by the RT-formula with quantum corrections. Our work thus provides a Hilbert space interpretation of the RT entropy. Since our axioms do not severely constrain UV bulk structures, they may be expected to hold equally well for successful formulations of string field theory, spin-foam models, or any other approach to constructing a UV-complete theory of gravity.

  1. [2310.01487] - Kinetic gases in static spherically symmetric modified dispersion relations - Manuel Hohmann

  2. [2310.01734] - New $4D$ and Extra dimensional quantum–like black holes with localized sources of matter and its thermodynamics - Milko Estrada

  3. [2310.01925] - Black hole graviton and quantum gravity - Yusuke Kimura

  4. [2310.02186] - Equating Extrapolate Dictionaries for Massless Scattering - Eivind Jørstad, Sabrina Pasterski, Atul Sharma

Tue - 10/03/23

Quantum Gravity as a Theory of Connections

  • Authors: Hassan Mehmood
  • Subjects: General Relativity and Quantum Cosmology (gr-qc)
  • Arxiv link: https://arxiv.org/abs/2309.16734
  • Abstract Consider the interior of a black hole or the very early universe: matter is so densely localized that neither the effects of gravity nor those of quantum theory can be ignored. But this entails that neither general relativity nor quantum theory on its own can fully describe such a situation, for some of the most fundamental principles inhering in these two theories are haunted by the specter of incompatibility. Quantum gravity is the name for the bewildering penumbra of theories that seek to exorcise this demon. But it turns out that the metrical variables of general relativity constitute a lamp too narrow to bottle the phantom, and loop quantum gravity is a fascinating enterprise that seeks the Aladdin who does possess the required lamp. This is achieved by recasting general relativity as a theory of connections, rather than that of metrics. This shift of emphasis allows one to use a number of mathematical tools that make it possible to arrive at a fully consistent, almost background-independent theory of quantum gravity. This thesis endeavours to probe these ideas in detail.

There is no new related paper today

  1. [2309.17043] - Effective action and black hole solutions in asymptotically safe quantum gravity - Jan M. Pawlowski, Jan Tränkle

Mon - 10/02/23

Quantum Gravity as a Theory of Connections

  • Authors: Hassan Mehmood
  • Subjects: General Relativity and Quantum Cosmology (gr-qc)
  • Arxiv link: https://arxiv.org/abs/2309.16734
  • Abstract Consider the interior of a black hole or the very early universe: matter is so densely localized that neither the effects of gravity nor those of quantum theory can be ignored. But this entails that neither general relativity nor quantum theory on its own can fully describe such a situation, for some of the most fundamental principles inhering in these two theories are haunted by the specter of incompatibility. Quantum gravity is the name for the bewildering penumbra of theories that seek to exorcise this demon. But it turns out that the metrical variables of general relativity constitute a lamp too narrow to bottle the phantom, and loop quantum gravity is a fascinating enterprise that seeks the Aladdin who does possess the required lamp. This is achieved by recasting general relativity as a theory of connections, rather than that of metrics. This shift of emphasis allows one to use a number of mathematical tools that make it possible to arrive at a fully consistent, almost background-independent theory of quantum gravity. This thesis endeavours to probe these ideas in detail.

There is no new related paper today

  1. [2309.17043] - Effective action and black hole solutions in asymptotically safe quantum gravity - Jan M. Pawlowski, Jan Tränkle

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