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Wigner sharpened the paradox by imagining a (human) friend of his shut in a lab, measuring a quantum system. He argued it was absurd to say his friend exists in a superposition of having seen and not seen a decay unless and until Wigner opens the lab door. [Nora] Tischler and her colleagues have carried out a version of the Wigner’s friend test. By combining the classic thought experiment with another quantum head-scratcher called entanglement—a phenomenon that links particles across vast distances—they have also derived a new theorem, which they claim puts the strongest constraints yet on the fundamental nature...

Quantum mechanics’ core assumption is that on the smallest scales, atomic properties are quantized...For example, an electron can be in a lowest-energy state, but if you add a little more energy, it doesn’t slowly transition into the new higher-energy state. Rather, it unpredictably snaps into the new state. If you’re not looking at it, the atom can take on intermediate states—but these aren’t midway points. The atom would be in both states at the same time, and then once you observed it, it would immediately snap into one state or the other. The team’s artificial atom is an experimental apparatus...

A laser pulse bounced off a rubidium atom and entered the quantum world — taking on the weird physics of "Schrödinger's cat." Then another one did the same thing. Then another. The laser pulses didn't grow whiskers or paws. But they became like the famous quantum-physics thought experiment Schrödinger's cat in an important way: They were large objects that acted like the simultaneously dead-and-alive creatures of subatomic physics — existing in a limbo between two simultaneous, contradictory states. And the lab in Finland where they were born had no limit on how many they could make. Pulse after pulse turned...

A lot of scientists think that major quantum effects like entanglement, in which particles separated by vast distances mysteriously link up their states, shouldn't work for living things. But a new paper argues that it already has — that scientists in 2016 have already created a sort of Schrödinger's cat — only with quantum-entangled bacteria. Usually, we describe quantum physics as a set of rules that governs the behavior of extremely tiny things: light particles, atoms and other infinitesimally small objects. The larger world, at the bacterial scale (which is also our scale — the chaotic realm of life) isn't...

Physicists have learned how they could breed Schrödinger cats in optics. Scientists tested a method that could potentially amplify superpositions of classical states of light beyond microscopic limits and help determine the boundaries between the quantum and classical worlds. ... Co-author and University of Calgary graduate student Anastasia Pushkina explains: "The idea of the experiment was proposed in 2003 by the group of Professor Timothy Ralph of the University of Queensland, Australia. In essence, we cause interference of two "cats" on a beam splitter. This leads to an entangled state in the two output channels of that beam splitter. In...

Scientists have developed a way to 'breed' Schrodinger's hypothetical cat in a breakthrough experiment that could bridge the gap between the quantum and the visible - or classical - worlds. The cat in the famous thought experiment can be alive and dead at the same time, in a quantum phenomenon known as superposition. But, whether this effect translates to larger objects has long remained a mystery. Physicists have now created a way to amplify pairs of classical states of light to generate 'enlarged' cats, in effort to uncover the limit (if there is one) of the quantum world.

Schrödinger's cat now has a second box to play in, thanks to an international team of physicists that has created a two-mode "Schrödinger's cat state" for the first time. The experiment brings together two purely quantum properties, in that the "cat" (i.e. the photons) is simultaneously "alive and dead" (in a superposition of states) while also in two locations at once (the two boxes are entangled with one another).

Yale physicists have given Schrödinger's cat a second box to play in. Credit: Michael S. Helfenbein/Yale University ====================================================================================================================== Yale physicists have given Schrödinger's famous cat a second box to play in, and the result may help further the quest for reliable quantum computing. Schrödinger's cat is a well-known paradox that applies the concept of superposition in quantum physics to objects encountered in everyday life. The idea is that a cat is placed in a sealed box with a radioactive source and a poison that will be triggered if an atom of the radioactive substance decays. Quantum physics suggests that the...

In a paper published in the current issue of the scientific journal Nature Communications and titled "Direct measurement of a 27-dimensional orbital-angular-momentum state vector," a team of physicists led by the University of Rochester's Mehul Malik describe how they circumvented a basic principle of uncertainty that requires that some states of a quantum system must be understood poorly if other states are to be understood well. Determining a quantum state, such as the position of an electron or the momentum of a photon, is tricky, to say the least. That's because subatomic particles behave nothing at all like billiard balls,...

Schrodinger's Cat A cat is placed in a box, together with a radioactive atom. If the atom decays, a hammer kills the cat; if the atom doesn't decay, the cat lives. As the atom is considered to be in either state before the observer opens the box, the cat must thus be considered to be simultaneously dead and alive. -ERWIN SCHODINGER'S CAT PARADOX, 1935 Wittgenstein's Banana A banana is flying first class from New York to L.A. Two scientists, one in each city, are talking on the phone about the banana. Because it is moving in relationship to its noun,...