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Andrea Palessandro, Tony Rothman
Fri Jan 06 2023 09:57:34 (1 day)
# 1.
As shown by Gertsenshtein in 1961, an external magnetic field can catalyze the mixing of graviton and photon states in a manner analogous to neutrino-flavor oscillations. We first present a straightforward derivation of the mechanism by a method based on unpublished notes of Freeman Dyson. We next extend his method to include boundary conditions and retrieve the results of Boccaletti et al. from 1970. We point out that, although the coupling between the graviton and photons states is extremely weak, the large magnetic fields around neutron stars $\sim 10^{14}$ G make the Gertsenshtein effect a plausible source of gravitons. Indeed, an “in principle” observable consequence would be the change of optical brightness of a neutron star between directions parallel and perpendicular to the field. We also point out that axion-photon mixing, a subject of active current research, is essentially the same process as the Gertsenshtein effect, and so the general mechanism may be of broad astrophysical and cosmological interest.
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Alexey A. Kryukov
Fri Jan 06 2023 09:57:32 (1 day)
# 2.
The motion of a ball through an appropriate lattice of round obstacles models the behavior of a Brownian particle and can be used to describe measurement on a macro system. On another hand, such motion is chaotic and a known conjecture asserts that the Hamiltonian of the corresponding quantum system must follow the random matrix statistics of an appropriate ensemble. We use the Hamiltonian represented by a random matrix in the Gaussian unitary ensemble to study the Schrodinger evolution of non-stationary states. For Gaussian states representing a classical system, the Brownian motion that describes the behavior of the system under measurement is obtained. For general quantum states, the Born rule for the probability of transition between states is derived. It is then shown that the Schrodinger evolution with such a Hamiltonian models measurement on macroscopic and microscopic systems, provides an explanation for the classical behavior of macroscopic bodies and for irreversibility of a measurement, and identifies the boundary between micro and macro worlds.
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Sinya Aoki
Fri Jan 06 2023 09:57:29 (1 day)
# 3.
Noether’s 2nd theorem applied to a total system states that a global symmetry which is a part of local symmetries does not provide a physically meaningful conserved charge but it instead leads to off-shell constraints as a form of conserved currents. In this paper, we propose a general method to derive a matter conserved current associated with a special global symmetry in the presence of local symmetries. While currents derived from local symmetries of a matter sector with a covariant background gauge field are not conserved in general, we show that the current associated with a special type of a global symmetry, called a hidden matter symmetry, is on-shell conserved. We apply this derivation to a $U(1)$ gauge theory, general relativity and a non-abelian gauge theory. In general relativity, the associated conserved charge agrees with the one recently proposed from a different point of view.
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Simone Gasparinetti
Thu Jan 05 2023 08:00:00 (2 days)
# 4.
Nature Physics, Published online: 05 January 2023; doi:10.1038/s41567-022-01896-2
The emission of light from qubits in a superconducting circuit can be controlled in order to choose the direction of the photons’ propagation, which could be used to route information in quantum networks.
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physics.hist-ph updates on arXiv.org
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John Klasios
Wed Jan 04 2023 10:08:30 (2 days)
# 5.
The cognitive scientist Donald Hoffman argues that we don’t perceive reality: spacetime, objects, colors, sounds, tastes, and so forth, are all merely an interface that we evolved to track evolutionary fitness rather than to perceive truths about external reality. In this paper, I expound on his argument, then I extend it, primarily, by looking at key ideas in physics that are quite germane to it. Among the topics in physics that I discuss are black holes, the holographic principle, string theory, duality, quantum gravity, and special relativity. I discuss these ideas from physics with an eye to their relevance for Hoffman’s view.
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PhilSci-Archive: No conditions. Results ordered -Date Deposited.
Wed Jan 04 2023 03:30:21 (3 days)
# 6.
Kastner, Ruth (2022) Quantum Systems and Identity: Against “Permutation Invariance”. [Preprint]
