



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 Related Quantum Physics Current Events and Quantum Physics News ArticlesSqueezed quantum catsQuantum physics is full of fascinating phenomena. Take, for instance, the cat from the famous thought experiment by the physicist Erwin Schrodinger. Researchers find the 'key' to quantum network solution Scientists at the University of York's Centre for Quantum Technology have made an important step in establishing scalable and secure high rate quantum networks. Quantum physics  hot and cold at the same time Temperature is a very useful physical quantity. It allows us to make a simple statistical statement about the energy of particles swirling around on complicated paths without having to know the specific details of the system. A glass fiber that brings light to a standstill Light is an extremely useful tool for quantum communication, but it has one major disadvantage: it usually travels at the speed of light and cannot be kept in place. Super sensitive measurement of magnetic fieldsThere are electrical signals in the nervous system, the brain and throughout the human body and there are tiny magnetic fields associated with these signals that could be important for medical science. Scientists move closer to '2 for 1 deal' on solar cell efficiency The underlying mechanism behind an enigmatic process called "singlet exciton fission", which could enable the development of significantly more powerful solar cells, has been identified by scientists in a new study. Nanospheres cooled with light to explore the limits of quantum physics A team of scientists at UCL led by Peter Barker and Tania Monteiro (UCL Physics and Astronomy) has developed a new technology which could one day create quantum phenomena in objects far larger than any achieved so far. Frozen highly charged ions for highest precision spectroscopy A team of researchers from the Max Planck Institute for Nuclear Physics in Heidelberg, the PhysikalischTechnische Bundesanstalt in Braunschweig and the University of Aarhus in Denmark demonstrated for the first time Coulomb crystallization of highlycharged ions (HCIs). The chameleon reorganizes its nanocrystals to change colors Many chameleons have the remarkable ability to exhibit complex and rapid color changes during social interactions. A collaboration of scientists within the Sections of Biology and Physics of the Faculty of Science from the University of Geneva (UNIGE), Switzerland, unveils the mechanisms that regulate this phenomenon. Strength in numbers When scientists develop a full quantum computer, the world of computing will undergo a revolution of sophistication, speed and energy efficiency that will make even our beefiest conventional machines seem like Stone Age clunkers by comparison. More Quantum Physics Current Events and Quantum Physics News Articles

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