Quantum weirdness: superposition (Introduction)

by David Turell , Thursday, December 31, 2015, 15:01 (3038 days ago) @ David Turell
edited by David Turell, Thursday, December 31, 2015, 15:07

Again in two places at the same time, but with atoms:-https://www.newscientist.com/article/mg22930544-500-new-quantum-record-as-ball-of-atoms-ends-up-in-two-spots-at-once/-"TRY to imagine a tiny ball sitting on one fingertip yet also on your shoulder at the same instant. Are you struggling? Most of us can't conceive of an object being in two places at once - yet physicists have just demonstrated the effect over a distance of half a metre, smashing previous records.-"It's an example of superposition, the idea that an object can exist in two quantum states at the same time. This persists until it is observed, causing a property called its wave function to collapse into one state or the other. The same principle allows Schrödinger's cat to be both dead and alive inside a box until you open the lid.-"We often think of quantum mechanics as applying only to subatomic particles, but there is nothing in the theory that limits its range. That's why experiments try to probe the transition between the quantum and everyday realms. “We're all wondering whether there is some regime where superpositions turn into classical states of matter,” says Mark Kasevich of Stanford University in California.-"To find out, Kasevich and his colleagues created a Bose-Einstein condensate (BEC) - a cloud of 10,000 rubidium atoms, all in the same quantum state. They shot this cloud, just a few millimetres across, up a 10-metre-high chamber using lasers, which also gradually push the atoms into two separate states.-"By the time the BEC reaches the top of the chamber, its wave function is a 50-50 mixture of those states, representing positions 54 centimetres apart. It stays in this superposition for about a second, then falls back down. At the bottom, the lasers turn the two states back into one, and this reveals that the atoms appear to arrive from two different heights, confirming that the BEC was indeed in a superposition at the top of the chamber."-Comment: Weirdness without a clear explanation. And this is the basis of our reality.