Neutron star quantum death by small black holes
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
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Holography for Ising spins on the hyperbolic plane
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Power-law inflation satisfies Penrose’s Weyl curvature hypothesis
Based on entropy considerations and the arrow of time Penrose argued that the Universe must have started in a special initial singularity with vanishing Weyl curvature. This is often interpreted to be at odds with inflation. Here we argue just the opposite, that Penrose’s persuasions are in fact consistent with inflation. Using the example of power law inflation, we show that inflation begins with a past null singularity, where Weyl tensor vanishes when the metric is initially exactly conformally flat. This initial state precisely obeys Penrose’s conditions. The initial null singularity breaks T-reversal spontaneously and picks the arrow of time. It can be regulated and interpreted as a creation of a universe from nothing, initially fitting in a bubble of Planckian size when it materializes. Penrose’s initial conditions are favored by the initial O(4) symmetry of the bubble, selected by extremality of the regulated Euclidean action. The predicted observables are marginally in tension with the data, but they can fit if small corrections to power law inflation kick in during the last 60e-folds.
79 ASTRONOMY AND ASTROPHYSICS↗
’t Hooft anomalies for staggered fermions
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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Testing high scale supersymmetry via second order gravitational waves
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79 ASTRONOMY AND ASTROPHYSICS↗
Higher spin mode stability for STU black hole backgrounds
This article studies mode stability of a four-dimensional rotating black hole with four pairwise equal U(1) charges derived in the framework of supergravity or the low energy string theory which is known now as STU black hole. We investigate bosonic perturbations in a proposed equation of the Teukolsky type for probe fields of different spins through the transformation technique devised by Whiting in 1989. Lastly, we introduce connection relations inspired by the work of Duztaş to prove the absence of unstable modes that solve the torsion-modified Dirac equation appropriate for this black hole background.
Astronomy & Astrophysics↗
Geometric quantum states beyond the AdS/CFT correspondence
We characterize the quantum states dual to entanglement wedges in arbitrary spacetimes, in settings where the matter entropy can be neglected compared to the geometric entropy. In AdS/CFT, such states obey special entropy inequalities known as the holographic entropy cone. In particular, the mutual information of CFT subregions is monogamous (MMI). We extend this result to arbitrary spacetimes, using a recent proposal for the generalized entanglement wedge e ( a ) of a gravitating region a . Given independent input regions a , b , and c , we prove MMI: Area [ e ( a ) ] + Area [ e ( b ) ] + Area [ e ( c ) ] − Area [ e ( a b ) ] − Area [ e ( b c ) ] − Area [ e ( c a ) ] + Area [ e ( a b c ) ] ≤ 0 . We expect that the full holographic entropy cone can be extended to arbitrary spacetimes using similar methods. Published by the American Physical Society 2024
Astronomy & Astrophysics↗
Decoherence as a detector of the Unruh effect
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71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Supersymmetric lattice theories on curved space
We show how to construct Hamiltonian lattice theories with one exact supersymmetry on arbitrary triangulations of curved space in any number of dimensions. Both bosons and fermions satisfy discrete Kähler-Dirac equations. The quantization of the fermions proceeds by imposing conventional anticommutation relations while the bosons require a modification of the usual canonical commutator. On regular lattices we construct parity, time reversal and translation-by-one (shift) symmetries. We argue that the latter are generically noninvertible symmetries. We also show how to couple these degrees of freedom to background gauge fields which leads to a theory with enhanced supersymmetry.
Anomalies↗
Mirror at the edge of the universe: Reflections on an accelerated boundary correspondence with de Sitter cosmology
An accelerated boundary correspondence (ABC) is solved for the de Sitter moving mirror cosmology. The beta Bogoliubov coefficients reveal the particle spectrum is a Planck distribution with temperature inversely proportional to horizon radius. The quantum stress tensor indicates a constant emission of energy flux consistent with eternal equilibrium, while the total energy carried by the particles remains finite. In conclusion, the curved spacetime transformation to flat spacetime with an accelerated boundary is illustrated, and also shown for anti-de Sitter (AdS) spacetime.
79 ASTRONOMY AND ASTROPHYSICS↗
Cosmology at the end of the world
In the last two decades the anti-de Sitter/conformal field theory (AdS/CFT) correspondence has emerged as a focal point of many research interests. In particular, it functions as a stepping stone to a still-missing full quantum theory of gravity. In this context, a pivotal question is if and how cosmological physics can be studied using AdS/CFT. Motivated by string theory, braneworld cosmologies propose that our universe is a four-dimensional membrane embedded in a bulk five-dimensional AdS spacetime. We show how such a scenario can be microscopically realized in AdS/CFT using special field theory states dual to an ‘end-of-the-world brane’ moving in a charged black hole spacetime. Observers on the brane experience cosmological physics and approximately four-dimensional gravity, at least locally in spacetime. Finally, this result opens a path towards a description of quantum cosmology and the simulation of cosmology on quantum machines.
79 ASTRONOMY AND ASTROPHYSICS↗
Theory and Simulations of Emergent Geometry in Quantum Gravity (Final Technical Report)
This is the final technical report for the QuantISED Award to PIs Hartman, Ginsparg, and McMahon at Cornell University, outlining the goals of the research project and summarizing its main technical achievements. These include the discovery of new non-perturbative effects in quantum gravity known as replica wormholes which play an important role in the black hole information paradox, new methods to study cosmological spacetimes using the tools of holographic duality, and new experimental results on error mitigation in quantum computing.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Quantum area fluctuations from gravitational phase space
We study the gravitational phase space associated to a stretched horizon within a finite-sized causal diamond in (d + 2)-dimensional spacetimes. By imposing the Raychaudhuri equation, we obtain its constrained symplectic form using the covariant phase space formalism and derive the relevant quantum commutators by inverting the symplectic form and quantizing. Finally, we compute the area fluctuations of the causal diamond by taking a Carrollian limit of the stretched horizon in pure Minkowski spacetime, and derive the relationship $\left\langle {\left(\Delta A\right)}^2\right\rangle \ge \frac{2\pi G}{d}\left\langle A\right\rangle$, showing that the variance of the area fluctuations is proportional to the area itself.
classical theories of gravity↗
Quantum dynamics of photon in rainbow gravity
In the present article, quantum dynamics of the photon is investigated in the cosmic string spacetime via gravity’s rainbow. We solve the mDKP (massless Duffin–Kemmer–Petiau) equation exactly and obtain the energy spectrum of photon. Then, we solve the Maxwell equations in the same gravity’s rainbow background and show that the solutions obtained are equivalent to the results of the photon equation. The energy spectrum of the photon is analyzed for three different rainbow functions.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Postselection-Free Entanglement Dynamics via Spacetime Duality
The dynamics of entanglement in 'hybrid' non-unitary circuits (for example, involving both unitary gates and quantum measurements) has recently become an object of intense study. A major hurdle toward experimentally realizing this physics is the need to apply postselection on random measurement outcomes in order to repeatedly prepare a given output state, resulting in an exponential overhead. We propose a method to sidestep this issue in a wide class of non-unitary circuits by taking advantage of spacetime duality. This method maps the purification dynamics of a mixed state under non-unitary evolution onto a particular correlation function in an associated unitary circuit. This translates to an operational protocol which could be straightforwardly implemented on a digital quantum simulator. We discuss the signatures of different entanglement phases, and demonstrate examples via numerical simulations. With minor modifications, the proposed protocol allows measurement of the purity of arbitrary subsystems, which could shed light on the properties of the quantum error correcting code formed by the mixed phase in this class of hybrid dynamics.
74 ATOMIC AND MOLECULAR PHYSICS↗