Breaking the limits of classical physics

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Breaking the limits of classical physics
June 7 2012
In the quantum optical laboratories at the Niels Bohr Institute, researchers have
conducted experiments that show that light breaks with the classical physical
principles. The studies show that light can have both an electrical and a magnetic
field, but not at the same time. That is to say, light has quantum mechanical
properties.
(Phys.org) -- With simple arguments, researchers show that nature is
complicated. Researchers from the Niels Bohr Institute have made a
simple experiment that demonstrates that nature violates common sense -
the world is different than most people believe. The experiment
illustrates that light does not behave according to the principles of
classical physics, but that light has quantum mechanical properties. The
new method could be used to study whether other systems behave
quantum mechanically. The results have been published in the scientific
journal, Physical Review Letters. 
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In physics there are two categories: 
classical physics
and quantum
physics. In classical physics, objects, e.g. a car or a ball, have a position
and a velocity. This is how we classically look at our everyday world. In
the quantum world objects can also have a position and a velocity, but
not at the same time. At the atomic level, quantum mechanics says that
nature behaves quite differently than you might think. It is not just that
we do not know the position and the velocity, rather, these two things
simply do not exist simultaneously. But how do we know that they do not
exist simultaneously? And where is the border of these two worlds?
Researchers have found a new way to answer these questions.
Light on quantum mechanics
"Our goal is to use quantum mechanics in a new way. It is therefore
important for us to know that a 'system' really behaves in a way that has
no classical explanation. To this end, we first examined light," explains
Eran Kot, PhD-student in the research group, Quantum Optics at the
Niels Bohr Institute at the University of Copenhagen. 
Based on a series of experiments in the quantum optics laboratories, they
examined the state of light. In classical physics, light possesses both an
electric and a magnetic field.
"What our study demonstrated was that light can have both an electric
and a magnetic field, but not at the same time. We thus provide a simple
proof that an experiment breaks the classical principles. That is to say,
we showed light possesses quantum properties, and we can expand this to
other systems as well" says Eran Kot.
Classical and non-classical mechanics
The aim of the research is both to fundamentally understand the world,
but there is also a practical challenge in being able to exploit 
quantum
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mechanics
 in larger contexts. For 
light
it is no great surprise that it
behaves quantum mechanically, but the methods that have been
developed can also be used to study other systems.
"We are endeavouring to develop future quantum computers and we
therefore need to understand the borders for when something behaves
quantum mechanically and when it is classical mechanics," says
professor of quantum physics Anders S. Sørensen, explaining that
quantum computing must necessarily be comprised of systems with non-
classical properties. 
More information: 
prl.aps.org/abstract/PRL/v108/i23/e233601
Provided by Niels Bohr Institute
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