Skip to main content

Home/ Advanced Concepts Team/ Group items tagged spin-in

Rss Feed Group items tagged

Filter: All | Bookmarks | Topics Simple Middle
jmlloren

Exotic matter : Insight : Nature - 5 views

www.nature.com/...index.html

nan phy

shared by jmlloren on 03 Aug 10 - Cached
LeopoldS liked it
  • jmlloren on 03 Aug 10
     
    Trends in materials and condensed matter. Check out the topological insulators. amazing field.
  • ...12 more comments...
  • Luzi Bergamin on 03 Aug 10
     
    Aparently very interesting, will it survive the short hype? Relevant work describing mirror charges of topological insulators and the classical boundary conditions were done by Ismo and Ari. But the two communities don't know each other and so they are never cited. Also a way to produce new things...
  • jmlloren on 04 Aug 10
     
    Thanks for noticing! Indeed, I had no idea that Ari (don't know Ismo) was involved in the field. Was it before Kane's proposal or more recently? What I mostly like is that semiconductors are good candidates for 3D TI, however I got lost in the quantum field jargon. Yesterday, I got a headache trying to follow the Majorana fermions, the merons, skyrnions, axions, and so on. Luzi, are all these things familiar to you?
  • Luzi Bergamin on 04 Aug 10
     
    Ismo Lindell described in the early 90's the mirror charge of what is now called topological insulator. He says that similar results were obtained already at the beginning of the 20th century... Ismo Lindell and Ari Sihvola in the recent years discussed engineering aspects of PEMCs (perfect electro-megnetic conductors,) which are more or less classical analogues of topological insulators. Fundamental aspects of PEMCs are well knwon in high-energy physics for a long time, recent works are mainly due to Friedrich Hehl and Yuri Obukhov. All these works are purely classical, so there is no charge quantisation, no considerations of electron spin etc. About Majorana fermions: yes, I spent several years of research on that topic. Axions: a topological state, of course, trivial :-) Also merons and skyrnions are topological states, but I'm less familiar with them.
  • LeopoldS on 04 Aug 10
     
    "Non-Abelian systems1, 2 contain composite particles that are neither fermions nor bosons and have a quantum statistics that is far richer than that offered by the fermion-boson dichotomy. The presence of such quasiparticles manifests itself in two remarkable ways. First, it leads to a degeneracy of the ground state that is not based on simple symmetry considerations and is robust against perturbations and interactions with the environment. Second, an interchange of two quasiparticles does not merely multiply the wavefunction by a sign, as is the case for fermions and bosons. Rather, it takes the system from one ground state to another. If a series of interchanges is made, the final state of the system will depend on the order in which these interchanges are being carried out, in sharp contrast to what happens when similar operations are performed on identical fermions or bosons." wow, this paper by Stern reads really weired ... any of you ever looked into this?
  • jmlloren on 04 Aug 10
     
    C'mon Leopold, it's as trivial as the topological states, AKA axions! Regarding the question, not me!
  • LeopoldS on 04 Aug 10
     
    just looked up the wikipedia entry on axions .... at least they have some creativity in names giving: "In supersymmetric theories the axion has both a scalar and a fermionic superpartner. The fermionic superpartner of the axion is called the axino, the scalar superpartner is called the saxion. In some models, the saxion is the dilaton. They are all bundled up in a chiral superfield. The axino has been predicted to be the lightest supersymmetric particle in such a model.[24] In part due to this property, it is considered a candidate for the composition of dark matter.[25]"
  • jmlloren on 04 Aug 10
     
    Thank's Leopold. Sorry Luzi for being ironic concerning the triviality of the axions. Now, Leo confirmed me that indeed is a trivial matter. I have problems with models where EVERYTHING is involved.
  • Luzi Bergamin on 04 Aug 10
     
    Well, that's the theory of everything, isn't it?? Seriously: I don't think that theoretically there is a lot of new stuff here. Topological aspects of (non-Abelian) theories became extremely popular in the context of string theory. The reason is very simple: topological theories are much simpler than "normal" and since string theory anyway is far too complicated to be solved, people just consider purely topological theories, then claiming that this has something to do with the real world, which of course is plainly wrong. So what I think is new about these topological insulators are the claims that one can actually fabricate a material which more or less accurately mimics a topological theory and that these materials are of practical use. Still, they are a little bit the poor man's version of the topological theories fundamental physicists like to look at since electrdynamics is an Abelian theory.
  • jmlloren on 04 Aug 10
     
    I have the feeling, not the knowledge, that you are right. However, I think that the implications of this light quantum field effects are great. The fact of being able to sustain two currents polarized in spin is a technological breakthrough.
  • LeopoldS on 04 Aug 10
     
    not sure how much I can contribute to your apparently educated debate here but if I remember well from my work for the master, these non-Abelian theories were all but "simple" as Luzi puts it ... and from a different perspective: to me the whole thing of being able to describe such non-Abelian systems nicely indicates that they should in one way or another also have some appearance in Nature (would be very surprised if not) - though this is of course no argument that makes string theory any better or closer to what Luzi called reality ....
  • Luzi Bergamin on 04 Aug 10
     
    Well, electrodynamics remains an Abelian theory. From the theoretical point of view this is less interesting than non-Abelian ones, since in 4D the fibre bundle of a U(1) theory is trivial (great buzz words, eh!) But in topological insulators the point of view is slightly different since one always has the insulator (topological theory), its surrounding (propagating theory) and most importantly the interface between the two. This is a new situation that people from field and string theory were not really interested in.
  • Dario Izzo on 04 Aug 10
     
    guys... how would you explain this to your gran mothers?
  • jmlloren on 05 Aug 10
  • LeopoldS on 07 Aug 10
     
    *you* tried *your* best .... ??
pacome delva

Malagasy Spiders Spin the World's Toughest Biological Material - ScienceNOW - 0 views

news.sciencemag.org/...y-spiders-spin-the-worlds.html

bio biomaterials spiders

shared by pacome delva on 04 Jan 11 - No Cached
  • Like an engineer accounting for a skyscraper swaying in the wind, Madagascar's Darwin's bark spider (Caerostris darwini) spins enormous, river-spanning webs that stretch and contract as the trees to which they're anchored bend this way and that. A new study finds that this spider's silk is the toughest biomaterial yet discovered.
  • The spiders' colossal orb webs can span up to 2.8 square meters and are anchored by threads as long as 25 meters.
pacome delva

A New Spin on Electronics - 0 views

sciencenow.sciencemag.org/...4

phy spintronics

shared by pacome delva on 26 Nov 09 - Cached
  • Incorporating both the magnetic leads and the underlying semiconductor, a spintronics circuit could hold its memory when turned off, as the magnetic elements remain magnetized. Manipulating spin could also require far less power than steering charges does, says Ron Jansen of the University of Twente in Enschede, Netherlands. Some physicists even aspire to create a spooky quantum connection called "entanglement" between spin-polarized currents to make a quantum computer that could crack problems that stymie an ordinary one.
jcunha

Electron spins controlled using sound waves - 0 views

phys.org/...2015-03-electron.html

PHY technology FUN

shared by jcunha on 11 Mar 15 - No Cached
  • jcunha on 11 Mar 15
     
    Cornell applied physicists have demonstrated an unprecedented method of control over electron spins using extremely high-frequency sound waves - new insights in the study of the spin of the electron. Crazy idea but, no further need for complicated quantum encryption techniques of sound signals?
Thijs Versloot

Quantum entanglement at ambient conditions in a macroscopic solid-state spin ensemble - 1 views

advances.sciencemag.org/...e1501015

technology quantum entanglement

shared by Thijs Versloot on 25 Nov 15 - No Cached
  • Thijs Versloot on 25 Nov 15
     
    Quoted from one of the authors in a separate interview: "We know that the spin states of atomic nuclei associated with semiconductor defects have excellent quantum properties at room temperature," said Awschalom, Liew Family Professor in Molecular Engineering and a senior scientist at Argonne National Laboratory. "They are coherent, long-lived and controllable with photonics and electronics. Given these quantum 'pieces,' creating entangled quantum states seemed like an attainable goal." Bringing the quantum world to the macroscopic scale could see some interesting applications in sensors, or generally entanglement-enhanced applications.
  • jcunha on 26 Nov 15
     
    They were previously working on the same concept in N-V centers in diamond (as a semiconductor). Here the advantage is that SiC could in principle be integrated with Si or Ge. Anyway its all about controlling coherence. In the next 10 years some breakthroughs are expected in the field of semiconductor spintronics, but quantum computing in this way lies still in the horizon
Francesco Biscani

STLport: An Interview with A. Stepanov - 2 views

www.stlport.org/...StepanovUSA.html

computer science

shared by Francesco Biscani on 23 Mar 10 - Cached
  • Generic programming is a programming method that is based in finding the most abstract representations of efficient algorithms.
  • I spent several months programming in Java.
  • for the first time in my life programming in a new language did not bring me new insights
  • ...2 more annotations...
  • it has no intellectual value whatsoever
  • Java is clearly an example of a money oriented programming (MOP).
  • Francesco Biscani on 23 Mar 10
     
    One of the authors of the STL (C++'s Standard Template Library) explains generic programming and slams Java.
  • ...6 more comments...
  • Ma Ru on 24 Mar 10
     
    "Java is clearly an example of a money oriented programming (MOP)." Exactly. And for the industry it's the money that matters. Whatever mathematicians think about it.
  • Joris _ on 24 Mar 10
     
    It is actually a good thing that it is "MOP" (even though I do not agree with this term): that is what makes it inter-operable, light and easy to learn. There is no point in writing fancy codes, if it does not bring anything to the end-user, but only for geeks to discuss incomprehensible things in forums. Anyway, I am pretty sure we can find a Java guy slamming C++ ;)
  • Francesco Biscani on 24 Mar 10
     
    Personally, I never understood what the point of Java is, given that: 1) I do not know of any developer (maybe Marek?) that uses it for intellectual pleasure/curiosity/fun whatever, given the possibility of choice - this to me speaks loudly on the objective qualities of the language more than any industrial-corporate marketing bullshit (for the record, I argue that Python is more interoperable, lighter and easier to learn than Java - which is why, e.g., Google is using it heavily); 2) I have used a software developed in Java maybe a total of 5 times on any computer/laptop I owned over 15 years. I cannot name of one single Java project that I find necessary or even useful; for my usage of computers, Java could disappear overnight without even noticing. Then of course one can argue as much as one wants about the "industry choosing Java", to which I would counterargue with examples of industry doing stupid things and making absurd choices. But I suppose it would be a kind of pointless discussion, so I'll just stop here :)
  • Joris _ on 24 Mar 10
     
    "At Google, python is one of the 3 "official languages" alongside with C++ and Java". Java runs everywhere (the byte code itself) that is I think the only reason it became famous. Python, I guess, is more heavy if it were to run on your web browser! I think every language has its pros and cons, but I agree Java is not the answer to everything... Java is used in MATLAB, some web applications, mobile phones apps, ... I would be a bit in trouble if it were to disappear today :(
  • Dario Izzo on 24 Mar 10
     
    I personally do not believe in interoperability :)
  • Ma Ru on 24 Mar 10
     
    Well, I bet you'd notice an overnight disappearance of java, because half of the internet would vanish... J2EE technologies are just omnipresent there... I'd rather not even *think* about developing a web application/webservice/web-whatever in standard C++... is it actually possible?? Perhaps with some weird Microsoft solutions... I bet your bank online services are written in Java. Certainly not in PHP+MySQL :) Industry has chosen Java not because of industrial-corporate marketing bullshit, but because of economics... it enables you develop robustly, reliably, error-prone, modular, well integrated etc... software. And the costs? Well, using java technologies you can set-up enterprise-quality web application servers, get a fully featured development environment (which is better than ANY C/C++/whatever development environment I've EVER seen) at the cost of exactly 0 (zero!) USD/GBP/EUR... Since many years now, the central issue in software development is not implementing algorithms, it's building applications. And that's where Java outperforms many other technologies. The final remark, because I may be mistakenly taken for an apostle of Java or something... I love the idea of generic programming, C++ is my favourite programming language (and I used to read Stroustroup before sleep), at leisure time I write programs in Python... But if I were to start a software development company, then, apart from some very niche applications like computer games, it most probably would use Java as main technology.
  • Francesco Biscani on 24 Mar 10
     
    "I'd rather not even *think* about developing a web application/webservice/web-whatever in standard C++... is it actually possible?? Perhaps with some weird Microsoft solutions... I bet your bank online services are written in Java. Certainly not in PHP+MySQL :)" Doing in C++ would be awesomely crazy, I agree :) But as I see it there are lots of huge websites that operate on PHP, see for instance Facebook. For the banks and the enterprise market, as a general rule I tend to take with a grain of salt whatever spin comes out from them; in the end behind every corporate IT decision there is a little smurf just trying to survive and have the back covered :) As they used to say in the old times, "No one ever got fired for buying IBM". "Industry has chosen Java not because of industrial-corporate marketing bullshit, but because of economics... it enables you develop robustly, reliably, error-prone, modular, well integrated etc... software. And the costs? Well, using java technologies you can set-up enterprise-quality web application servers, get a fully featured development environment (which is better than ANY C/C++/whatever development environment I've EVER seen) at the cost of exactly 0 (zero!) USD/GBP/EUR... Since many years now, the central issue in software development is not implementing algorithms, it's building applications. And that's where Java outperforms many other technologies." Apart from the IDE considerations (on which I cannot comment, since I'm not a IDE user myself), I do not see how Java beats the competition in this regard (again, Python and the huge software ecosystem surrounding it). My impression is that Java's success is mostly due to Sun pushing it like there is no tomorrow and bundling it with their hardware business.
  • Joris _ on 24 Mar 10
     
    OK, I think there is a bit of everything, wrong and right, but you have to acknowledge that Python is not always the simplest. For info, Facebook uses Java (if you upload picture for instance), and PHP is very limited. So definitely, in company, engineers like you and me select the language, it is not a marketing or political thing. And in the case of fb, they come up with the conclusion that PHP, and Java don't do everything but complement each other. As you say Python as many things around, but it might be too much for simple applications. Otherwise, I would seriously be interested by a study of how to implement a Python-like system on-board spacecrafts and what are the advantages over mixing C, Ada and Java.
LeopoldS

An optical lattice clock with accuracy and stability at the 10-18 level : Nature : Natu... - 0 views

www.nature.com/...nature12941.html

physics clock PHY

shared by LeopoldS on 23 Jan 14 - No Cached
  • LeopoldS on 23 Jan 14
     
    Progress in atomic, optical and quantum science1, 2 has led to rapid improvements in atomic clocks. At the same time, atomic clock research has helped to advance the frontiers of science, affecting both fundamental and applied research. The ability to control quantum states of individual atoms and photons is central to quantum information science and precision measurement, and optical clocks based on single ions have achieved the lowest systematic uncertainty of any frequency standard3, 4, 5. Although many-atom lattice clocks have shown advantages in measurement precision over trapped-ion clocks6, 7, their accuracy has remained 16 times worse8, 9, 10. Here we demonstrate a many-atom system that achieves an accuracy of 6.4 × 10−18, which is not only better than a single-ion-based clock, but also reduces the required measurement time by two orders of magnitude. By systematically evaluating all known sources of uncertainty, including in situ monitoring of the blackbody radiation environment, we improve the accuracy of optical lattice clocks by a factor of 22. This single clock has simultaneously achieved the best known performance in the key characteristics necessary for consideration as a primary standard-stability and accuracy. More stable and accurate atomic clocks will benefit a wide range of fields, such as the realization and distribution of SI units11, the search for time variation of fundamental constants12, clock-based geodesy13 and other precision tests of the fundamental laws of nature. This work also connects to the development of quantum sensors and many-body quantum state engineering14 (such as spin squeezing) to advance measurement precision beyond the standard quantum limit.
LeopoldS

NIAC 2014 Phase I Selections | NASA - 4 views

www.nasa.gov/...niac-2014-phase-i-selections

advanced NASA NIAC concepts

shared by LeopoldS on 05 Jun 14 - No Cached
  • LeopoldS on 05 Jun 14
     
    12 new NIAC 1 studies - many topics familiar to us ... please have a look at those closest to your expertise to see if there is anything new/worth investigating (and in general to be knowledgeable on them since we will get questions sooner or later on them)
    Principal Investigator Proposal Title Organization City, State, Zip Code
    Atchison, Justin Swarm Flyby Gravimetry Johns Hopkins University Baltimore, MD 21218-2680
    Boland, Eugene Mars Ecopoiesis Test Bed Techshot, Inc. Greenville, IN 47124-9515
    Cash, Webster The Aragoscope: Ultra-High Resolution Optics at Low Cost University of Colorado Boulder, CO 80309-0389
    Chen, Bin 3D Photocatalytic Air Processor for Dramatic Reduction of Life Support Mass & Complexity NASA ARC Moffett Field, CA 94035-0000
    Hoyt, Robert WRANGLER: Capture and De-Spin of Asteroids and Space Debris Tethers Unlimited Bothel, WA 98011-8808
    Matthies, Larry Titan Aerial Daughtercraft NASA JPL Pasadena, CA 91109-8001
    Miller, Timothy Using the Hottest Particles in the Universe to Probe Icy Solar System Worlds John Hopkins University Laurel, MD 20723-6005
    Nosanov, Jeffrey PERISCOPE: PERIapsis Subsurface Cave OPtical Explorer NASA JPL Pasadena, CA 91109-8001
    Oleson, Steven Titan Submarine: Exploring the Depths of Kraken NASA GRC Cleveland, OH 44135-3127
    Ono, Masahiro Comet Hitchhiker: Harvesting Kinetic Energy from Small Bodies to Enable Fast and Low-Cost Deep Space Exploration NASA JPL Pasadena, CA 91109-8001
    Streetman, Brett Exploration Architecture with Quantum Inertial Gravimetry and In Situ ChipSat Sensors Draper Laboratory Cambridge, MA 02139-3539
    Wiegmann, Bruce Heliopause Electrostatic Rapid Transit System (HERTS) NASA MSFC Huntsville, AL 35812-0000
  • annaheffernan on 11 Jun 14
     
    Eh, the swarm flyby gravimetry is very similar to the "measuring gravitational fields" project I proposed in the brewery
ESA ACT

Utilization of Photon Orbital Angular Momentum in the Low-Frequency Radio Domain - 0 views

scitation.aip.org/...GetabsServlet

NAN

shared by ESA ACT on 24 Apr 09 - No Cached
  • ESA ACT on 24 Apr 09
     
    We show numerically that vector antenna arrays can generate radio beams that exhibit spin and orbital angular momentum characteristics similar to those of helical Laguerre-Gauss laser beams in paraxial optics. For low frequencies (<~1 GHz), digital techni
Nicholas Lan

Nuclear experts clean radioactive site with Cillit Bang - 1 views

www.telegraph.co.uk/...ive-site-with-Cillit-Bang.html

NRG COTS spin-in

shared by Nicholas Lan on 10 Dec 09 - Cached
  • Nicholas Lan on 10 Dec 09
     
    Use of COTS products for low-cost nuclear reprocessing plant decommissioning. I suggest a brainstorming session for potential spin-in technologies involving walking around digros.
ESA ACT

Magnetic monopoles in spin ice : Abstract : Nature - 0 views

www.nature.com/...7C2E8E3129DCD1C74394E49F1036F1

PHY science

shared by ESA ACT on 24 Apr 09 - Cached
  • ESA ACT on 24 Apr 09
     
    "We pursue an alternative strategy, namely that of realizing monopoles not as elementary but rather as emergent particles-that is, as manifestations of the correlations present in a strongly interacting many-body system."
Annalisa Riccardi

New structures self-assemble in synchronized dance - 3 views

www.sciencedaily.com/...121121145619.htm

shared by Annalisa Riccardi on 22 Nov 12 - No Cached
LeopoldS liked it
  • Annalisa Riccardi on 22 Nov 12
     
    With self-assembly guiding the steps and synchronization providing the rhythm, a new class of materials forms dynamic, moving structures in an intricate dance. Researchers have demonstrated tiny spheres that synchronize their movements as they self-assemble into a spinning microtube.
  • johannessimon81 on 23 Nov 12
     
    This is quite similar to the following paper. Here they show how tiny variations of particle parameters can produce clearly distinct structures: Thermal and Athermal Swarms of Self-Propelled Particles --> http://arxiv.org/abs/1201.0180
johannessimon81

Practical Electrostatic Motor(?) - 3 views

www.youtube.com/watch

PHY science NRG Electrostatic Motor

shared by johannessimon81 on 14 Sep 14 - No Cached
LeopoldS liked it
  • johannessimon81 on 14 Sep 14
     
    Apparently a spin-off company of the University of Wisconsin is developing non-magnetic motors. Maybe this could be useful for reaction wheels etc. on satellites that monitor the Earth's magnetic field... (preventing magnetic interference with sensors)
  • LeopoldS on 20 Sep 14
     
    Duncan, this is one for you! - you can probably even build one in your kitchen ...
1 - 14 of 14
Showing 20▼ items per page