190 research outputs found
Quantum interference experiments, modular variables and weak measurements
We address the problem of interference using the Heisenberg picture and
highlight some new aspects through the use of pre-selection, post-selection,
weak measurements, and modular variables, We present a physical explanation for
the different behaviors of a single particle when the distant slit is open or
closed: instead of having a quantum wave that passes through all slits, we have
a localized particle with non-local interactions with the other slit(s). We
introduce a Gedankenexperiment to measure this non-local exchange. While the
Heisenberg picture and the Schrodinger pictures are equivalent formulations of
quantum mechanics, nevertheless, the results discussed here support a new
approach which has led to new insights, new intuitions, new experiments, and
even the possibility of new devices that were missed from the old perspective
Each instant of time a new Universe
We present an alternative view of quantum evolution in which each moment of
time is viewed as a new "universe" and time evolution is given by correlations
between them.Comment: 8 pages, 8 figure
New Insights on Emergence from the Perspective of Weak Values and Dynamical Non-Locality
In this article, we will examine new fundamental aspects of emergence and information using novel approaches to quantum mechanics which originated from the group around Aharonov. The two-state vector formalism provides a complete description of pre- and post-selected quantum systems and has uncovered a host of new quantum phenomena which were previously hidden. The most important feature is that any weak coupling to a pre- and post-selected system is effectively a coupling to a weak value which is given by a simple expression depending on the two-state vector. In particular, weak values, are the outcomes of so called weak measurements which have recently become a very powerful tool for ultra-sensitive measurements. Using weak values, we will show how to separate a particle from its properties, not unlike the Cheshire cat story: Well! I\u27ve often seen a cat without a grin, thought Alice; but a grin without a cat! It\u27s the most curious thing I ever saw in all my life! Next, we address the question whether the physics on different scales emerges from quantum mechanics or whether the laws of physics at those scales are fundamental. We show that the classical limit of quantum mechanics is a far more complicated issue; it is in fact dramatically more involved and it requires a complete revision of all our intuitions. The revised intuitions can then serve as a guide to finding novel quantum effects. Next we show that novel experimental aspects of contextuality can be demonstrated with weak measurements and these suggest new restrictions on hidden variable approaches. Next we emphasize that the most important implication of the Aharonov-Bohm effect is the existence of non-local interactions which do not violate causality. Finally, we review some generalizations of quantum mechanics and their implications for emergence and information. First, we review an alternative approach to quantum evolution in which each moment of time is viewed as a new universe and time evolution is given by correlations between different moments. Next, we present a new solution to the measurement problem involving future boundary conditions placed on the universe as a whole. Finally, we introduce another fundamental approach to quantum evolution which allows for tremendous richness in the types of allowable Hamiltonians
Topological bound states for quantum charges
We discuss how, in appropriately designed configurations, solenoids carrying
a semifluxon can be used as topological energy barriers for charged quantum
systems. We interpret this phenomenon as a consequence of the fact that such
solenoids induce nodal lines in the wave function describing the charge, which
on itself is a consequence of the Aharonov-Bohm effect. Moreover, we present a
thought experiment with a cavity where two solenoids are sufficient to create
bound states.Comment: Close to published versio
Pre- and post-selection, weak values, and contextuality
By analyzing the concept of contextuality (Bell-Kochen-Specker) in terms of
pre-and-post-selection (PPS), it is possible to assign definite values to
observables in a new and surprising way. Physical reasons are presented for
restrictions on these assignments. When measurements are performed which do not
disturb the pre- and post-selection (i.e. weak measurements), then novel
experimental aspects of contextuality can be demonstrated including a proof
that every PPS-paradox with definite predictions implies contextuality. Certain
results of these measurements (eccentric weak values with e.g. negative values
outside the spectrum), however, cannot be explained by a "classical-like"
hidden variable theory.Comment: Identical content; stream-lined verbal presentatio
Gravitational sensing with weak value based optical sensors
Using weak values amplification angular resolution limits, we theoretically
investigate the gravitational sensing of objects. By inserting a force-sensing
pendulum into a weak values interferometer, the optical response can sense
accelerations to a few 10's of
, with optical powers of
. We convert this precision into range and mass sensitivity,
focusing in detail on simple and torsion pendula. Various noise sources present
are discussed, as well as the necessary cooling that should be applied to reach
the desired levels of precision.Comment: 9 pages, 4 figures, Quantum Stud.: Math. Found. (2018
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