Electrons and liquid helium advance understanding of zero-resistance

Electrons and liquid helium advance understanding of zero-resistance
A cell (container) where the electrons on liquid helium experiments are conducted. Credit: OIST

The end of Moore's Law, the prediction that transistor density would double every two years, was one of the hottest topics in electronics-related discussions in 2015. Silicon-based technologies have nearly reached the physical limits of the number and size of transistors that can be crammed into one chip, but alternative technologies are still far from mass implementation. The amount of heat generated during operation and the sizes of atoms and molecules in materials used in transistor manufacturing are some of problems that need to be solved for Moore's Law to persist.

Atomic and molecular sizes cannot be changed, but the heat problem is not unsolvable. Recent research has shown that in two-dimensional systems, including semiconductors, electrical resistance decreases and can reach almost zero when they are subjected to magnetic and microwave influence. Electrical resistance produces a loss of energy in the form of heat; therefore, a decrease in resistance reduces heat generation. There are several different models and explanations for the zero-resistance phenomenon in these systems. however, the scientific community has not reached an agreement on this matter because semiconductors used in electronics are complex and processes in them are difficult to model mathematically.

Research conducted by the Quantum Dynamics Unit at Okinawa Institute of Science and Technology graduate University (OIST) could represent an important step in understanding two-dimensional semiconductors. The Unit's latest paper, published in Physical Review Letters, describes anomalies in the behaviour of in electrons on liquid helium two-dimensional system.

Electrons and liquid helium advance understanding of zero-resistance
Copper mirrors direct and focus microwave photons in electrons on liquid helium system. The focusing mirror (on the left) is made by pressing a hard stainless steel ball (also shown in the picture) into a soft piece of copper. The flat mirror (on the right) shows two concentric circular electrodes (aka a Corbino pair) that are used to measure electron conductivity. Credit: OIST

The system is maintained at a temperature close to absolute zero (-272.75ºC or 0.4K) to keep the helium liquefied. Extraneous electrons are bound to the helium surface because their presence causes slight changes in the orbits of helium electrons, inducing a subtle positive charge at the helium surface. At the same time, lack the energy required to penetrate the surface to enter the liquid. The resulting system is ideal for studying various electron properties, as it has virtually zero impurities, which avoids artefacts caused by defects of surface and structure, or due to the presence of other chemical elements. Prof. Denis Konstantinov, head of the Quantum Dynamics Unit, and his team study conditions under which electrons can violate selection rules regulating transitions from one state to another.

In a macro-world we perceive transitions from one state to another as happening gradually. For example, a person travelling from town A to town B can make an infinite number of stops. In micro-world that is not always the case. Properties, such as energy, position, speed, and colour, can be quantised, i.e. they can occur only in discrete quantities. In other words, the traveller can be either in town A, or town B, but not somewhere in-between.

Since electron energy is quantised, electrons can occupy only specific energy levels. Quantum theory predicts that in a two-dimensional electron system, where moving electrons are confined to one plane, under a strong magnetic field electrons also will be restricted to climbing only one step of the energy level ladder at a time. however, the experiments show that electrons can jump to higher energy levels, skipping levels between. Prof. Konstantinov and his team are very excited about this discovery: "It is not everyday that we get a chance to observe the violation of quantum theory predictions!"

Electrons and liquid helium advance understanding of zero-resistance
In order to study abnormalities in electron state changes, the scientists applied a strong vertical magnetic field and then bombarded the electrons on liquid helium system with microwave photons. Credit: OIST

In order to study abnormalities in electron state changes, the scientists applied a strong vertical magnetic field and then bombarded the system with microwave photons. Under these conditions, selection rules seem to stop working. Prof. Konstantinov says that his group had theorised that such a phenomenon is possible and now they have proven it.

Selection rules describe a theoretical, absolutely pure, and homogenous system with no disorders. Real-life systems are more complex. In the case of electrons on helium, the system is pure and homogenous, but the surface of is nonetheless disturbed by capillary waves—ripples associated with the surface tension and similar to small, circular ripples in a pond when a pebble is tossed into the water. The height of these ripples is only the diameter of a hydrogen atom, but in combination with microwave radiation they create enough deviation from an ideal system for selection rules to change.

Conditions modelled in the Quantum Dynamics Unit's experiment are similar to those that led to observations of zero resistance in semiconductors. however, the electrons on helium system is relatively simple and can be described mathematically with great precision. Studying this system will further the development of quantum physics and will contribute to our understanding of electrons and various electrical phenomena. moreover, with some adjustments models, based on electrons on helium systems can be adapted to more complex systems, such as two-dimensional semiconductors.


Explore further

Incompressible electrons

More information: R. Yamashiro et al. Photoconductivity Response at Cyclotron-Resonance Harmonics in a Nondegenerate Two-Dimensional Electron Gas on Liquid Helium, Physical Review Letters (2015). DOI: 10.1103/PhysRevLett.115.256802
Journal information: Physical Review Letters

Citation: Electrons and liquid helium advance understanding of zero-resistance (2016, February 2) retrieved 17 September 2019 from https://phys.org/news/2016-02-electrons-liquid-helium-advance-zero-resistance.html
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Feb 02, 2016
The end of Moore's Law, the prediction that transistor density would double every two years


That's not Moore's law.

Might seem like a petty point, but factual errors like that have profound impact on the public understanding of science and society. If you throw "facts" like that out there, people take them for granted, and think that the transistor density has indeed been doubling every two years when it hasn't.

No wonder people believe in all sorts of bullcrap like singularity and conspiracy theories, when the media continuously mis-represents the state of progress in technology.

That is the basics of moore's law. I like how you say that is not and do not even state what you think is correct. You just rant instead.

http://spectrum.i...ores-law

Feb 02, 2016
The end of Moore's Law, the prediction that transistor density would double every two years


That's not Moore's law.

Might seem like a petty point, but factual errors like that have profound impact on the public understanding of science and society. If you throw "facts" like that out there, people take them for granted, and think that the transistor density has indeed been doubling every two years when it hasn't.

No wonder people believe in all sorts of bullcrap like singularity and conspiracy theories, when the media continuously mis-represents the state of progress in technology.


If singularities are impossibilities/mathematical artifacts/what have you, and you've any proof -at all- of what could exist at the bottom of the insane gravity well of a black hole, I'd love to hear it.

Feb 02, 2016
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Feb 02, 2016
Moore's 'Law' that there would be a doubling every two years has been broken before, but the advancements immediately after that two year window were more than a doubling anyhow, so it still worked out to a degree. Doubling of the transistors usable at any one time gives rise to higher (doubled) computing power, which is what Moore was concerned with.

Watching the paid anti-REAL-science troll Eikka self-destruct on that one was beautiful! Just because something is not 'mainstream science' does not mean that it is not a real effect or that it wont overthrow previous ideas. Remember, Einstein flunked out of math because HE saw that they we doing it wrong, but that was THE Mainstream WAY. Often the non-mainstream science theories are the correct ones, look at Galileo and Copernicus vs today's view of our Solar system.

Mainstream does not mean 'Absolutely Correct' yet they pay a LOT of money to trolls to keep the real science behind their own bars of money and power!

Feb 02, 2016
Remember, Einstein flunked out of math

No. Don't remember it - because it's an urban myth. It was one of these made up factoids on "Ripley's Believe it or Not" that just sounded too good not to print (in it they even claimed Einstein was a mathematician...which just goes to show how carefully they vetted that one)

Feb 02, 2016
still ignored by morons who can;'t wrap their heads around how magnetism works....yes.....you.

So you are an unrecognised genius. And it is because of me. That's pathetic.
Why don't you explain once more that the solar system and the galaxy are held together by magnetism alone?


All I'm going to say is just because it is most likely doesn't mean it is the only one or way. Until we find out the final answers, everything is up for grabs.

Feb 04, 2016
I think that part of the problem with the whole Gravity/DM VS Plasma/EU is that the early scientists were measuring the net forces of attraction and Calling it all 'Gravity'. Obviously since we now know a LOT more on the atomic and quantum scales, and can see that gravity is a weak force while electromagnetism is a stronger force BUT THEY BOTH ADD to form the effects that we call 'Gravity'. We keep looking for a single mechanism for gravity when it almost assuredly has to do with a combination of effects, likely not only particle attraction via gravity and charge, but also the magnetic fields in space, the Van Allen Belts, actually create a tiny downward force due to the magnetics and since most matter has a charge due to electron shell valence or elementary particle charge, it can be held in that magnetic field and Has to react to it.

Gravity as the net sum of several properties is something that needs to be resolved before meaningful answers will be forthcoming.

Feb 04, 2016
Ya Know Phys 1, Apple was going to come out with a wide-screen phone/tablet but the ladies in the Marketing Department stopped it when the scientists/engineers creating it tried to release it as a Max IPad...

Feb 06, 2016
Moore's law? Is this really the problem in an article, which throws the "truth" that energy, position, speed and /attention!/ color are quantifiable /and yes, energy generally speaking is not quantifiable either, quantifiable is only the amount of energy, necessary to move a specific particle from a specific state to a specific different one in a specific system, like an atom, for "position" and "speed" somebody really needs to retake it's physics classes, specifically the ones related to Relativity, and about "color" I don't want even to start/.
But just by the way there is a logic flaw too in that same paragraph - if a bus can take infinite stops covering a distance that means space is not discrete. :)

Feb 06, 2016
@Steelwolf:

"Often the non-mainstream science theories are the correct ones..."

Any idea of how many non-mainstream theories are being debunked for every "mainstream one"? :)

And "...the Van Allen Belts, actually create a tiny downward force due to the magnetics and since most matter has a charge due to electron shell valence..." is a really elaborate nonsense...

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