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A quantum particle moving in a gravitational field may penetrate the classically forbidden region of the gravitational potential. This raises the question of whether the time of flight of a quantum particle in a gravitational field might…

Quantum Physics · Physics 2009-11-10 P. C. W. Davies

We ask the question how the (weak) equivalence principle established in classical gravitational physics should be reformulated and interpreted for massive quantum objects that may also have internal degrees of freedom (dof). This inquiry is…

Quantum Physics · Physics 2018-02-14 Charis Anastopoulos , Bei-Lok Hu

For relativistic energies the small angle classical cross section for scattering on a Coulomb potential agrees with the first Born approximation for quantum cross section for scalar particle only in the leading term. The disagreement in…

High Energy Physics - Theory · Physics 2009-11-13 A. I. Nikishov

Quantum mechanics predicts correlation between spacelike separated events which is widely argued to violate the principle of Local Causality. By contrast, here we shall show that the Schr\"odinger equation with Born's statistical…

Quantum Physics · Physics 2014-04-07 Agung Budiyono

All quantum field theories that describe interacting bosonic elementary particles, share the feature that the zeroth order perturbation expansion describes non-interacting harmonic oscillators. This is explained in the paper. We then…

High Energy Physics - Theory · Physics 2023-12-18 Gerard t Hooft

In classical physics there is a well-known theorem in which it is established that the energy per degree of freedom is the same. However, in quantum mechanics due to the non-commutativity of some pairs of observables and the possibility of…

Quantum Physics · Physics 2023-06-28 Esteban Marulanda , Alejandro Restrepo , Johans Restrepo

Gaussian quantum systems exhibit many explicitly quantum effects but can be simulated classically. Using both the Hilbert space (Koopman) and the phase-space (Moyal) formalisms we investigate how robust this classicality is. We find…

Quantum Physics · Physics 2017-02-23 Aida Ahmadzadegan , Robert B. Mann , Daniel R. Terno

Complex and spinorial techniques of general relativity are used to determine all the states of the $SU(2)$ invariant quantum mechanical systems in which the equality holds in the uncertainty relations for the components of the angular…

General Relativity and Quantum Cosmology · Physics 2023-03-10 László B. Szabados

The second-order moment quantum fluctuations or uncertainties are mass-dependent, and the incompatibility between the quantum uncertainty principle and the equivalence principle is at the second-order moment (variation) level, but not the…

General Relativity and Quantum Cosmology · Physics 2025-01-22 M. J. Luo

Experimentally, certain degrees of freedom may appear classical because their quantum fluctuations are smaller than the experimental error associated with measuring them. An approximation to a fully quantum theory is described in which the…

Quantum Physics · Physics 2007-05-23 Arlen Anderson

An adapted representation of quantum mechanics sheds new light on the relationship between quantum states and classical states. In this approach the space of quantum states splits into a product of the state space of classical mechanics and…

High Energy Physics - Theory · Physics 2021-04-14 Christoph Nölle

This paper is concerned with two questions in the decoherent histories approach to quantum mechanics: the emergence of approximate classical predictability, and the fluctuations about it necessitated by the uncertainty principle. We…

General Relativity and Quantum Cosmology · Physics 2009-10-22 J. J. Halliwell

The landscape of causal relations that can hold among a set of systems in quantum theory is richer than in classical physics. In particular, a pair of time-ordered systems can be related as cause and effect or as the effects of a common…

Quantum Physics · Physics 2017-07-20 Katja Ried , Jean-Philippe W. MacLean , Robert W. Spekkens , Kevin J. Resch

We present a new hydrodynamic analogy of nonrelativistic quantum particles in potential wells. Similarities between a real variant of the Schr\"odinger equation and gravity-capillary shallow water waves are reported and analyzed. We show…

Quantum Physics · Physics 2024-10-01 Idan Ceausu , Yuval Dagan

A classical random variable can be faithfully compressed into a sequence of bits with its expected length lies within one bit of Shannon entropy. We generalize this variable-length and faithful scenario to the general quantum source…

Quantum Physics · Physics 2009-11-07 Masato Koashi , Nobuyuki Imoto

The classical and quantum dynamics of a particle trapped in a one-dimensional infinite square well with a time periodic pulsed field is investigated. This is a two-parameter non-KAM generalization of the kicked rotor, which can be seen as…

Chaotic Dynamics · Physics 2009-11-07 R. Sankaranarayanan , A. Lakshminarayan , V. B. Sheorey

In quantum mechanics, the expectation value of a quantity on a quantum state, provided that the state itself gives in the classical limit a motion of a particle in a definite path, in classical limit goes over to Fourier series form of the…

Quantum Physics · Physics 2009-11-06 Q. H. Liu

The standard axiomatization of quantum mechanics (QM) is not fully explicit about the role of the time-parameter. Especially, the time reference within the probability algorithm (the Born Rule, BR) is unclear. Using a plausible principle…

Quantum Physics · Physics 2009-02-19 Carsten Held

The first two period behaviors of a quantum wave packet in an infinite square well potential is studied. First, the short term behavior of expectation value of a quantity on an equally weighted wave packet (EWWP) is in classical limit…

Quantum Physics · Physics 2007-05-23 Quan-Hui Liu , Wei-Hong Qi , Li-Ping Fu , Bambi Hu

Duality transformations within the quantum mechanics of a finite number of degrees of freedom can be regarded as the dependence of the notion of a quantum, i.e., an elementary excitation of the vacuum, on the observer on classical phase…

High Energy Physics - Theory · Physics 2015-06-26 J. M. Isidro