Friday, June 08, 2012

#QUANTUM: "Physicists Say Quantum States Ubiquitous"

Physicists have demonstrated a breakdown in the classical description of system involving simultaneous electrical and magnetic fields, such as mechanical and electrical oscillators. By demonstrating for a single photon the violation of a simple criterion must be fulfilled for any joint probability distribution for simultaneous electrical- and magnetic-fields in classical physics, the researchers claim to demonstrate that quantum mechanical principles like Heisenberg's uncertainty principle apply to macroscopic systems: R. Colin Johnson

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.

Here is what the University of Copenhagen says about light having electrical or magnetic fields, but not both simultaneously: 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.

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.

Eran Kot, a PhD-student in the research group of professor of quantum physics Anders S. Sørensen, maintains that systems possess measurable quantum properties, just like atomic particles. Based on a series of experiments in the quantum optics laboratories, the researchers examined the state of light. In classical physics, light possesses both an electric and a magnetic field.

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 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.
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