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Researchers Create New Form of Matter (phys.org)
An anonymous reader quotes a report from Phys.Org: MIT physicists have created a new form of matter, a supersolid, which combines the properties of solids with those of superfluids. By using lasers to manipulate a superfluid gas known as a Bose-Einstein condensate, the team was able to coax the condensate into a quantum phase of matter that has a rigid structure -- like a solid -- and can flow without viscosity -- a key characteristic of a superfluid. Studies into this apparently contradictory phase of matter could yield deeper insights into superfluids and superconductors, which are important for improvements in technologies such as superconducting magnets and sensors, as well as efficient energy transport. The researchers report their results this week in the journal Nature. The team used a combination of laser cooling and evaporative cooling methods, originally co-developed by Ketterle, to cool atoms of sodium to nanokelvin temperatures. Atoms of sodium are known as bosons, for their even number of nucleons and electrons. When cooled to near absolute zero, bosons form a superfluid state of dilute gas, called a Bose-Einstein condensate, or BEC. To create the supersolid state, the team manipulated the motion of the atoms of the BEC using laser beams, introducing "spin-orbit coupling." In their ultrahigh-vacuum chamber, the team used an initial set of lasers to convert half of the condensate's atoms to a different quantum state, or spin, essentially creating a mixture of two Bose-Einstein condensates. Additional laser beams then transferred atoms between the two condensates, called a "spin flip."
For those who facepalmed when they saw that Sodium is a boson in TFS ... technically, its most common isotope (Na23) is in fact a composite boson, because the total number of fermion particles is even: 11 protons + 12 neutrons + 11 electrons = 34 fermions, each with spin 1/2. So, the composite Na23 atom is net integer spin, and thus a boson.
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Well, as near as I can make out, they are describing a phenomenon that is analogous to a standing wave in a river.
Watch water in a swift river cascade over a ledge. It will form a standing wave behind the ledge which does not move, even though all the matter in it is moving downstream. This is the opposite of a traveling wave in the ocean where the mater doesn't move but the structure does.
Now so much for analogies. Again as far as I can make out, they coaxed super-cooled sodium atoms into a crystal-like structure which is stable, but allows the constituent atoms move freely within the structure. Again, I suspect this is an analogy too, but I'm at the limit of my understanding of modern physics.
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You mean this?
https://www.youtube.com/watch?...
Managed to find this from 2008. Definitely helps, but also raises questions:
What conditions make it so a given atom in the lattice will be affected by the motion or not?
Do the atoms retain their "bonds" (if that even applies), or are they reformed when the motion stops?
Do the atoms "remember" their original place in the lattice, or do they simply re-establish the "bonds" with those nearest them?
What would happen, theoretically, if linear motion is applied, or if there was a gap in the disc (like a slice out of a pie)? Would the atoms hit the "wall" or would they pass through it? Would the effect not work under those conditions? If not, why?
See, now I want you to do more research to answer these questions, if you can't already.
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