36 research outputs found
Exact uncertainty principle and quantization: implications for the gravitational field
The quantization of the gravitational field is discussed within the exact
uncertainty approach. The method may be described as a Hamilton-Jacobi
quantization of gravity. It differs from previous approaches that take the
classical Hamilton-Jacobi equation as their starting point in that it
incorporates some new elements, in particular the use of a formalism of
ensembles in configuration space and the postulate of an exact uncertainty
relation. These provide the fundamental elements needed for the transition from
the classical theory to the quantum theory.Comment: 6 pages; submitted to the proceedings of DICE2004, to appear in the
Brazilian Journal of Physic
Schrodinger equation from an exact uncertainty principle
An exact uncertainty principle, formulated as the assumption that a classical
ensemble is subject to random momentum fluctuations of a strength which is
determined by and scales inversely with uncertainty in position, leads from the
classical equations of motion to the Schrodinger equation. Thus there is an
exact formulation of the uncertainty principle which precisely captures the
essence of what is "quantum" about quantum mechanics.Comment: Latex, 18pp, nature of fluctuations & differences from stochastic
mechanics clarifie
On two recent proposals for witnessing nonclassical gravity
Two very similar proposals have been made recently for witnessing
nonclassical features of gravity, by Bose et al. and by Marletto and Vedral.
However, while these proposals are asserted to be very general, they are in
fact based on a very strong claim: that quantum systems cannot become entangled
via a classical intermediary. We point out that the support provided for this
claim is only applicable to a very limited class of quantum-classical
interaction models, corresponding to Koopman-type dynamics. We show that the
claim is also valid for mean-field models, but that it is contradicted by
explicit counterexamples based on the configuration-ensemble model. Thus,
neither proposal provides a definitive test of nonclassical gravity.Comment: New references added, minor corrections. Close to final versio
Nonlocal signaling in the configuration space model of quantum-classical interactions
When interactions are turned off, the theory of interacting quantum and
classical ensembles due to Hall and Reginatto is shown to suffer from a
nonlocal signaling effect that is effectively action at a distance. This limits
the possible applicability of the theory. In its present form, it is restricted
to those situations in which interactions are always on, such as classical
gravity interacting with quantized matter.Comment: 3 pages, no figure