New Test for the Applicability of Quantum Mechanics to the Macro-World
Since its discovery in the beginning of the 20th century there have
been speculations
whether Quantum Mechanics would only apply on a microscopic level and
its laws
would cease to be valid in the macroscopic world giving space to
classical physics.
During all this time, scientists have thus been searching for
signatures of quantum
behavior in macroscopic systems. Such signatures could for example
consist of
quantum superposition states or quantum entanglement, a very strong
correlation
between distant quantum objects that is closely related to the
violation of Bell
inequalities and that has no counterpart in the classical world.
In the 1980s a better understanding of the quantum to classical
transition was achieved
by the theory of decoherence. This explains that unavoidable
interactions of a system
with its surrounding leads to a destruction of some of its quantum
features.
In our paper, we now show how two macroscopic objects, here two
vibrating
membranes could be driven into an entangled quantum state by
illuminating them
with laser light. To keep the disturbance of quantum features by the
environment
at a tolerably low level, the two membranes are suspended inside a
high finesse
optical cavity. For this setup our analysis shows that entanglement
should be
observable if Quantum Mechanics still applies to objects such as these
membranes.
If nonetheless no entanglement would be found in an experiment, this
might indicate
that there exists a yet undiscovered mechanism which is responsible
for destroying
quantum entanglement at macroscopic scales.
***
LU11091
UEC scientists demonstrate elegant factoring method using Bose-Einstein
condensate
Security in modern communications is founded on the difficulty of
factoring large numbers. This fact has led to a flurry of research at
the intersection of number theory and physics aimed at bettering
classical methods of factoring. Recent work performed for the Japanese
Science and Technology Agency in conjunction with the University of
Electro-communications has demonstrated an elegant method of factoring
using atoms in a strange state of matter known as a Bose-Einstein
condensate (BEC). First, information about two numbers is encoded in the
phase of a laser field. When the BEC is exposed to this field, the atoms
behave as waves and form a diffraction pattern. By analysing this
pattern it is possible to tell if one of the numbers is a factor of the
other to a higher degree of accuracy than classical methods allow. The
researchers led by Ken'ichi Nakagawa hope it is possible to extend their
work to more exotic quantum states with the ideal being to realise true
fast quantum factoring.
***
LD11380
Filament turbulence: Surface dynamics tells it all
How much information do you need to distinguish between different
mechanisms for turbulent dynamics in three-dimensions? In this paper,
the authors show that the observation of the dynamics on the surface of
a medium can be sufficient. Studying mechanisms for turbulence in the
context of chemical media, the authors found that two major classes of
mechanisms leave a very different signature on what can be observed on
the surface of a three-dimensional medium. These results are of direct
relevance in the context of ventricular fibrillation - a turbulent
electrical wave activity that destroys the coherent contraction of the
ventricular muscle and its main pumping function leading to sudden
cardiac death. While it has been proposed that the three-dimensional
structure of the heart plays an important role in this type of
turbulence, only the surface of the heart is currently accessible to
experimental observation preventing the study of the full dynamics. The
results presented in this paper suggest that such observations might be
sufficient.
***
LW10928
Classical and quantum facets of light in photonic lattices
Interference and diffraction are universal wavy phenomena, common to
classical and quantum realms. For years, researchers exploited formal
analogies between light and matter waves, developing 'classical simulators'
to visualize quantum phenomena in engineered photonic structures. For
instance, a light beam propagating in photonic lattices behaves similarly
to an electron in a crystal pushed by an electric field, undergoing a
periodic motion due to Bragg scattering which is the optical analogue of
the well-known electronic Bloch oscillations.
But are such photonic analogies actually classical? Now, this manuscript
shows that there is a chance to utilize the quantum-optical analogy but in
the opposite direction - trying to observe quantum version of classical
wave phenomena. In certain conditions, light behaves as a stream of photons
showing, in addition to classic wave interference, quantum interference.
This manuscript highlights the particle-like behavior of photons undergoing
the optical analogue of Bloch oscillations and Zener tunneling among Bloch
bands, predicting quantum interference effects like photon pairs bunching
together when undergoing tunneling events.
***
LT11926
NEW POLAR MODES OF THERMAL CONVECTION FOUND IN ROTATING FLUID
SPHERICAL SHELLS
The onset of thermal convection in a rotating spherical shell of
moderate width has been studied numerically for very large rotation
rates, and a low-viscosity and high-thermal-conductivity fluid. For the
first time, it is found that the two first unstable modes (solutions of
the linear equations) of convection are polar, namely confined inside a
cylinder tangent to the inner sphere at the equator. In addition, and in
contrast to the modes known untill this date, the preferred mode
antisymmetric with respect to the equator. Both modes are confined
between the same latitudes, and their precession frequencies differ less
than 0.5%.
The linear modes are the 'genes' of the laminar flows observed in
nature. The superposition of the polar symmetric and antisymmetric
nonlinear waves provides a basic mechanism for the formation of coherent
polygonal structures without equatorial symmetry, like those observed in
the north pole of Saturn (see
http://www.astronomy.com/asy/default.aspx?c=a&id=5372). When the waves
are in phase in the north pole, they are in phase opposition in the
south, annihilating each other (see figure). Moreover, its nearly same
frequency explains the long life of the deep giant convective cells.
Up to now, the polar convection was known to grow in strongly nonlinear
regimes. However, the preceding results motivate the study of the
'laminar' nonlinear dynamics of the polar flows, and their implication
in the generation of planetary and stellar magnetic fields.
Figure caption. Contour plots of the temperature perturbation from the
conduction state in a meridional section for: (a) The preferred
antisymmetric polar mode, and (b) the symmetric polar
mode.
