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Scientists Discover a 'Tuneable' Novel Quantum State of Matter (phys.org)
An anonymous reader quotes a report from Phys.Org: An international team of researchers led by Princeton physicist Zahid Hasan has discovered a quantum state of matter that can be "tuned" at will -- and it's 10 times more tuneable than existing theories can explain. This level of manipulability opens enormous possibilities for next-generation nanotechnologies and quantum computing. Hasan and his colleagues, whose research appears in the current issue of Nature, are calling their discovery a "novel" quantum state of matter because it is not explained by existing theories of material properties. The classical phases of matter -- solids, liquids and gases -- arise from interactions between atoms or molecules. In a quantum phase of matter, the interactions take place between electrons, and are much more complex.
[Hasan] and his colleagues arranged atoms on the surface of crystals in many different patterns and watched what happened. They used various materials prepared by collaborating groups in China, Taiwan and Princeton. One particular arrangement, a six-fold honeycomb shape called a "kagome lattice" for its resemblance to a Japanese basket-weaving pattern, led to something startling -- but only when examined under a spectromicroscope in the presence of a strong magnetic field [...]. All the known theories of physics predicted that the electrons would adhere to the six-fold underlying pattern, but instead, the electrons hovering above their atoms decided to march to their own drummer -- in a straight line, with two-fold symmetry. The decoupling between the electrons and the arrangement of atoms was surprising enough, but then the researchers applied a magnetic field and discovered that they could turn that one line in any direction they chose. Without moving the crystal lattice, [one] could rotate the line of electrons just by controlling the magnetic field around them.
[Hasan] and his colleagues arranged atoms on the surface of crystals in many different patterns and watched what happened. They used various materials prepared by collaborating groups in China, Taiwan and Princeton. One particular arrangement, a six-fold honeycomb shape called a "kagome lattice" for its resemblance to a Japanese basket-weaving pattern, led to something startling -- but only when examined under a spectromicroscope in the presence of a strong magnetic field [...]. All the known theories of physics predicted that the electrons would adhere to the six-fold underlying pattern, but instead, the electrons hovering above their atoms decided to march to their own drummer -- in a straight line, with two-fold symmetry. The decoupling between the electrons and the arrangement of atoms was surprising enough, but then the researchers applied a magnetic field and discovered that they could turn that one line in any direction they chose. Without moving the crystal lattice, [one] could rotate the line of electrons just by controlling the magnetic field around them.
The most exciting phrase to hear in science, the one that heralds new discoveries, is not “Eureka!” (I found it!) but “That’s funny ” — Isaac Asimov (OK - Asimov is credit with the quote but it's more a paraphrase of a number of quotes he made)
All the known theories of physics predicted that the electrons would adhere to the six-fold underlying pattern, but instead, the electrons hovering above their atoms decided to march to their own drummer -- in a straight line, with two-fold symmetry. The decoupling between the electrons and the arrangement of atoms was surprising enough, but then the researchers applied a magnetic field and discovered that they could turn that one line in any direction they chose. Without moving the crystal lattice, [one] could rotate the line of electrons just by controlling the magnetic field around them.
Sounds classical to me:
- The layout of the substrate produced a planar potential well with no, or very little, difference of energy for electrons being in one position vs. another.
- Provided the average density of the electrons was right, they behaved like a gas of individual particles in a thin container, or marbles on a flat surface.
- The electrons repelled each other, so they tended to spread out evenly. (Spread out too far, though, and they leave some positive-charged substrate behind. So they don't just fly apart and go away.)
- But electrons also have spin, which means they are little magnets. So, with their mutual repulsion largely defeated by forces holding them at a given average spacing, they tend to line up north-pole-to-south-pole in strings (but don't all pile up because coming more than a little closer together under the slight magnetic attraction is balanced by higher repulsion.) The strings are a bit more dense than the average gas, so most of the electrons join one and reduce their total energy.
- So now you have these long magnetic strings, with no preferred orientation driven by irregularities in the substrate. Bring a magnet nearby and they'll line up with its field while spacing out by mutual magnetic AND electrostatic repulsion, much like iron filing lines.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
well that's about the number of people who really understand what all this article is about.
Slashdot, fix the reply notifications... You won't get away with it...
And that is the correct reaction. Bose-Einstein condensate is the worst offender in overhyping their significance—name a single useful thing that came out this Nobel-prize-winning discovery!
Anyone who shitposts on this... is a turd winkle. This is news. This is nerdy. This matters to me.
I'll throw the worst of shrubberies with plenty of typoeees at anyone who disobeys this edict.
I'm just an interested layperson, but the applications in nanotechnology seem pretty straightforward to me. Nanotech is basically all about building machines on a scale where a couple individual particles can be a whole part of the machine. So every weird thing you can figure out how to make particles do, on the individual level, at that scale -- as opposed to things to make huge aggregates of particles do -- is something you can use as a part of a nanomachine.
In this case, it sounds like they've figured out a way to build a kind of rod of electrons stuck to a crystal surface, that can be made to rotate based on the application of a magnetic field. That sounds like it could be as useful as, I dunno, a wooden disc that can be made to rotate around an axle is on a macroscopic scale. It sounds dumb and useless when you phrase it like that, but that's a rudimentary wheel, and there's a zillion uses in more complex machines that wheels can be put to. Who knows what exact uses a controllably spinning rod of electrons on the surface of a crystal could be in nanotechnology, but it seems like the kind of thing that could have many and varied.
-Forrest Cameranesi, Geek of all Trades
"I am Sam. Sam I am. I do not like trolls, flames, or spam."
Light takes many routes through the glass, bouncing off the many obstacles. What your eye sees is the route of maximal constructive interference. If you remove the sides of the glass, then the interference pattern is not the same. As far as you know, I'm just a random guy on the internet of course, so do double check everything I just said.
Yeah, just think back when lasers were invented, there was absolutely no use for it then. What a waste of time that was.
Are used as a matter of simplification. There is no clean boundary, only a continuum where the classical states (solid, liquid, gas, plasma) are specific islands.
Quantum doesn't mean magical, it just means something with discrete states rather than continuous states. QM is a quantum theory that mostly applies to the very small but can scale up to objects of a few millimetres under some conditions. Actually, some aspects - such as the Schrodinger Equation - applies to planetary rings, asteroid belts and accretion disks.
The first question is whether it's useful to talk of states of matter. If it is, is it useful to use traditional ones or should we decompose phenomena into the raw properties and then compose a new set of states that reduces the need for weird overlaps and talk of mysteries beyond the ken of man?
The second question (or third, if you go with the option above) is whether something that is apparently orthogonal to the original list is a state in the original sense? The original sense is a linear continuum, not a set of sets. This new thing is apparently not on that line. If matter's state is multidimensional, our naming should reflect that.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
So 20 years is your limit? What about 30 years? 100 years? Point is that the path from scientific discovery to technical application is sometimes a very long and winding road, other times a straight path (eg transistor).
The BEC was a big deal, even if we don't have an application yet. We discovered a new state of matter with unique properties. That should be what the physics field is excited about, full stop. That it hasn't resulted in an application yet on an arbitrary time horizon is irrelevant to it's scientific value. Should we stop studying dark matter, or neutrinos, because we don't have an application in mind (yet)?
This, by the way, is ignoring the side benefits of the pursuit of BEC. Cornell and others pushed the limits of lasers in order the get the laser cooling required to create the BEC. Their research has also led to advancements in atom and ion trap technologies.
The best way to predict the future is to invent it.