



Quantum cats are hard to see
December 19, 2011
International team of researchers explain the difficulty of detecting quantum effects Are there parallel universes? And how will we know? This is one of many fascinations people hold about quantum physics. Researchers from the universities of Calgary and Waterloo in Canada and the University of Geneva in Switzerland have published a paper this week in Physical Review Letters explaining why we don't usually see the physical effects of quantum mechanics. "Quantum physics works fantastically well on small scales but when it comes to larger scales, it is nearly impossible to count photons very well. We have demonstrated that this makes it hard to see these effects in our daily life," says Dr. Christoph Simon, who teaches in the Department of Physics and Astronomy at the University of Calgary and is one of the lead authors of the paper entitled: Coarsegraining makes it hard to see micromacro entanglement. It's well known that quantum systems are fragile. When a photon interacts with its environment, even just a tiny bit, the superposition is destroyed. Superposition is a fundamental principle of quantum physics that says that systems can exist in all their possible states simultaneously. But when measured, only the result of one of the states is given. This effect is known as decoherence, and it has been studied intensively over the last few decades. The idea of decoherence as a thought experiment was raised by Erwin Schrödinger, one of the founding fathers of quantum physics, in his famous cat paradox: a cat in a box can be both dead and alive at the same time. But, according to the authors of this study, it turns out that decoherence is not the only reason why quantum effects are hard to see. Seeing quantum effects requires extremely precise measurements. Simon and his team studied a concrete example for such a "cat" by using a particular quantum state involving a large number of photons. "We show that in order to see the quantum nature of this state, one has to be able to count the number of photons in it perfectly," says Simon. "This becomes more and more difficult as the total number of photons is increased. Distinguishing one photon from two photons is within reach of current technology, but distinguishing a million photons from a million plus one is not." University of Calgary

Quantum Physics: A Beginner's Guide (Beginner's Guides)
by Alastair Rae (Author)
As Alastair Rae points out in his introduction, "quantum physics is not rocket science". It may have gained a reputation as the theory that no one really understands, but its practical applications are all around us in everyday life. If it were not for quantum physics, computers would not function, metals would not conduct electricity, and the power stations that heat our homes would not produce energy. Assuming no prior scientific or mathematical knowledge, this clear and concise introduction provides a stepbystep guide to quantum theory, right from the very basic principles to the most cuttingedge developments, such as superfast computers and unbreakable codes, which could soon become reality. Finally, Rae turns to the philosophical questions posed by quantum physics and asks: if...


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Quantum Physics For Dummies
by Steve Holzner (Author)
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by Greg Kuhn (Author)
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Quantum Field Theory for the Gifted Amateur
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Quantum field theory is arguably the most farreaching and beautiful physical theory ever constructed, with aspects more stringently tested and verified to greater precision than any other theory in physics. Unfortunately, the subject has gained a notorious reputation for difficulty, with forbidding looking mathematics and a peculiar diagrammatic language described in an array of unforgiving, weighty textbooks aimed firmly at aspiring professionals. However, quantum field theory is too important, too beautiful, and too engaging to be restricted to the professionals. This book on quantum field theory is designed to be different. It is written by experimental physicists and aims to provide the interested amateur with a bridge from undergraduate physics to quantum field theory. The imagined...


Flow of Time: Quantum Gravity giving New Physics
by BookRix
Apply yesterday's variation principle to GellMann's quarks, pepper it with the inconsistencies of unfounded adhoc tactics  and there you are with grandpa's classical "Standard" model having no strategy, no future, topped only by "string" fantasies "beyond" physics, with all the great questions left open.
By marrying Planck's quanta with Einstein's General Relativity, the author is presenting the unified topdown model of a consistent "New Physics" (Quantum Gravity, including the Grand Unification) free of singularities and in accord with experiment. Spacetime is bent, fully quantized and "backgroundindependent".
Old problems of fundamental physics emerge as selfexplaining: 4dimensionality, the quark confinement, flavours, cosmic inflation, the arrow...


The Quantum Universe: (And Why Anything That Can Happen, Does)
by Brian Cox (Author), Jeff Forshaw (Author)
In The Quantum Universe, Brian Cox and Jeff Forshaw approach the world of quantum mechanics in the same way they did in Why Does E=mc2? and make fundamental scientific principles accessibleand fascinatingto everyone.The subatomic realm has a reputation for weirdness, spawning any number of profound misunderstandings, journeys into Eastern mysticism, and woolly pronouncements on the interconnectedness of all things. Cox and Forshaw’s contention? There is no need for quantum mechanics to be viewed this way. There is a lot of mileage in the weirdness” of the quantum world, and it often leads to confusion and, frankly, bad science. The Quantum Universe cuts through the Wu Li and asks what observations of the natural world made it necessary, how it was constructed, and why we are...

