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Hardware

Spintronics in your Future? 148

Posted by michael from the they-do-it-with-magnets dept.
slugfro writes: "Do faster boot times and RAM that maintains memory after shutdown sound interesting? This article by a Science Magazine author details the study of utilizing the spin of electrons rather than just the charge in electronic devices (hence the name 'Spintronics'). Anyone out there researching this or have more info?" We do a story about MRAM every four months or so, and each time commercial development is a few years in the future. :)
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Spintronics in your Future? More

Spintronics in your Future?

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  • a subset of quantum computing to me. Mabey it will get us one step closer to quantum computing being a reality for joe luser.

    • Re:Sounds like (Score:3, Interesting)

      by Computer! ( 412422 )
      Not really. It's basically as binary as traditional computing, just using a different measure for "on" and "off": "up" and "down". Look:

      Just like the positive/negative duo of charge, the 0s and 1s of current information technology, this up/down pairing makes spin an attractive possibility for encoding and carrying information electronically.

      The "quantum-readyness" of this technology is the same as charge. The cat is spinning both upand down at the same time, until you open the box.
      • You would go and bring the cat into this, wouldn't you. Can't you just leave him out of it. As if that poor thing hasn't been through enough with the radiation... now you want to find out what happens when you spin it too? Leave the poor thing alone, already.

        Yeesh... I'm calling the humane society you sick puppy! heh.

        -Alex

      • Re:Sounds like (Score:2, Interesting)

        by DeePCedure ( 99267 )

        Not really. It's basically as binary as traditional computing


        Yes, but this could open the door to the possibility of trinary computing. If circuit technology becomes "spintronically" advanced, then instead of the normal two state system (on and off) there would be three states: off, on(up), and on(down). Of course, off would still be a single state, because there is no spoon... I mean, spin... without the electron. :)

  • The cheap solution for persistant RAM is to provide a constant power source for your RAM from either some form of battery or just a power source that is always on.
    Where this stuff is actually useful is for better Hard Drives. In fact it's already being used for that, and has been for a while.
    • Batteries are okay for keeping RAM persistant...

      ...until your battery gets disconnected!

      RAM that never 'forgets' would be much better.

      Think about what would happen when you need to change the battery on your computer without loosing the RAM? hmm.....

    • I won't argue that this technology is useful for hard drives; obviously everyone likes larger hard drives. However, you miss the point when you advocate merely providing a constant power source. OK, that solution works somewhat for today, if you're using a desktop or a server-type system. For laptops and portables, however, "Spintronics" would be a real boon: zero boot time, zero latency when returning from sleep mode and no power consumption while in sleep mode. As a laptop user, I'd pay for those features.

    • Another option would be having a special disk that mirrors the contents of RAM. On shutdown, the ram backup disk gets the contents of RAM, with possibly a battery backup or some huge capaciter to keep the copy going in case power goes out. Then, on reboot, you have the option of loading up the old contents of RAM or actually rebooting.
      • Thats what "Hibernate" does, it suspends to disk, but you take the hit of spin-up and extracting 32MB-4GB of data off disk on restart, which could take as much time as a boot.
      • And thinkpads already have that feature.

        Dumps the ram on a file.

        There is also a "safety net" mode where the memory is saved even if the battery life is exhausted. "The tasks are restored from the hibernation file as soon as the AC power or charged battery is installed"
  • Just a clarificaiton. Technically its Science Magazine not "a Science Magazine" as stated on the main page.

    Science is the Journal of the American Association for the Advancement of Science (AAAS) and along with "Nature" (its british counterpart) it is one of the premier general science journals.

  • I only have a doubt about this RAM that maintains memory after shutdown. If a virus gets into the memory, how does this affect the system. The same goes to memory managment.

    Now I know I may be wrong or have the wrong idea since I ain't into memory allocation.


  • This would be so great for portable computers.

    Imagine keeping a laptop/handheld with you wherever you go, but only having it on when you need it. You can instantly close the lid on it, shutting off it's power. This would preserve battery life to possibly many days at a time for a traveler. Then when you need to use the computer, just open the lid, and it's exactly where it was when you closed it.

    Desktop computers would also be nice to instantly shut off and turn on at the same state, but the portable computer market seems much more useful, especially for conserving battery life.
    • Uhhmmm.....

      That's exactly what my Sony Vaio does actually right now, except for running for days, that, not yet!

    • So what risks? (Score:2, Interesting)

      by ackthpt ( 218170 )
      One of the old worries of Dynamic memory, ages ago, was that some cosmic particle could corrupt it, not that I've ever seen evidence of this happening, maybe it was just BS.

      As to the spin and orbital properties of an individual atom, particularly the risk which comes with such a density of memory, what could easily and commonly affect these properties? Strong RF? Magnetic fields? Xrays? (note: laptops currently survive airport Xrays, but I'm clueless as to how this happens and whether it's something that eventually will catch up with data stored on hard drives.)

      • It's not only real, it's not even that uncommon. This is one of the primary reasons that we have ECC RAM. I hear that it an even bigger risk at very high elevations where the atmosphere doesn't provide as much shielding.
        My Dad pointed out an article about a month ago (in EDN?) about this phenomenon even affecting really dense SRAM now.
      • One of the old worries of Dynamic memory, ages ago, was that some cosmic particle could corrupt it, not that I've ever seen evidence of this happening, maybe it was just BS.

        I just have to point out that Cosmic rays are probably not the cause. There are many causes for randomness, and especially when dealing with particles, these radnom factors become more important. Remember that all of quantum mechanics is based on probablities, not absolutes.

        This is from the Jargon File [tuxedo.org]:
        Factual note: Alpha particles cause bit rot, cosmic rays do not (except occasionally in spaceborne computers). Intel could not explain random bit drops in their early chips, and one hypothesis was cosmic rays. So they created the World's Largest Lead Safe, using 25 tons of the stuff, and used two identical boards for testing. One was placed in the safe, one outside. The hypothesis was that if cosmic rays were causing the bit drops, they should see a statistically significant difference between the error rates on the two boards. They did not observe such a difference. Further investigation demonstrated conclusively that the bit drops were due to alpha particle emissions from thorium (and to a much lesser degree uranium) in the encapsulation material. Since it is impossible to eliminate these radioactives (they are uniformly distributed through the earth's crust, with the statistically insignificant exception of uranium lodes) it became obvious that one has to design memories to withstand these hits.

        JD
    • You can instantly close the lid on it, shutting off it's power. This would preserve battery life to possibly many days at a time for a traveler.

      I already have one of those... It's called a PowerBook [apple.com]. Close the lid, and it goes to sleep in a fraction of a second and can remain that way for at least 2 weeks. Open it up and push any button, and 1 second later you're precisely where you left off...

  • ram that retains what's in memory only really comes into it's own when it's either running on a machine that is:

    1. running a stable os that doesn't need flushing

    2. i tend to leave my computer on all the time - it's got enough to do without me using it (downloading stuff for me, curing cancer, cracking codes etc...). the only time i turn it off is when it needs it OR:

    3. being used with a limited power supply

    4. a laptop running on a battery which you'll be booting much more often (saves time) because it's off (to save power).

    it'd be nice to save the environment too maybe ;)

  • So When Disk Drive Needs Repair (Score:3, Funny)

    by ackthpt ( 218170 ) on Friday November 16, 2001 @12:32PM (#2575251) Homepage Journal
    So .. when your disk drive needs repair .. take it to a quantum mechanic...
  • What happens when MS shoots me a BSOD? How the heck am I supposed to reboot if the ram is going to remember what crashed My machine in the first place?

    Heh - aside from that, it would be way cool to power off the system, come back 24 hours later and have it boot up in seconds. Heck, Technically, it should be able to freeze a moment in Unreal Tournament , allow you to go get a beer, then comeback and pick up where you left off.
    • Heck, Technically, it should be able to freeze a moment in Unreal Tournament , allow you to go get a beer, then comeback and pick up where you left off.

      Yes. Lets all pray that someday the scientific community will develop some sort of hardware based solution that will allow us to freeze or "pause" a computer game.

  • More info here... (Score:2, Informative)

    by xmda ( 43558 )
    Spintronics, or spin electronics, refers to the study of the role played by electron (and more generally nuclear) spin in solid state physics, and possible devices that specifically exploit spin properties instead of or in addition to charge degrees of freedom. For example, spin relaxation and spin transport in metals and semiconductors are of fundamental research interest not only for being basic solid state physics issues, but also for the already demonstrated potential these phenomena have in electronic technology (some short reviews). The prototype device that is already in use in industry as a read head and a memory-storage cell is the giant-magnetoresistive (GMR) sandwich structure which consists of alternating ferromagnetic and nonmagnetic metal layers. Depending on the relative orientation of the magnetizations in the magnetic layers, the device resistance changes from small (parallel magnetizations) to large (antiparallel magnetizations). This change in resistance (also called magnetoresistance) is used to sense changes in magnetic fields. Recent efforts in GMR technology have also involved magnetic tunnel junction devices where the tunneling current depends on spin orientations of the electrodes.

    More of this here: http://www.physics.umd.edu/rgroups/spin/intro.html

  • The boot up time of current computer systems takes a long time because it is doing a lot of different things: 1. Power On Self Test 2. Memory Test 3. Waiting for Devices to power up and "settle" 4. Finding first available device 5. IPL from first available device 6. Setup the processor and address spaces 7. Switch to protected mode ( Intel ) 8. Search for more devices 9. Wait for devices to settle / initialize 10. Start initial program loader 11. Run startup scripts 12. Run network startup ( wait for dhcp ) 13. Initialize Graphics System A reboot would still have to perform many of these steps whether or not the Ram remembered the previous state. Since whats in Ram is dependent on what devices are present and what addreses are assigned, you would probably have to wipe the ram on each boot anyway.
  • Don't believe it...
    ...it sounds like a load of spin...

    Tom.

  • I submitted a story just recently about this story in SpaceDaily [spacedaily.com] detailing a breakthrough in magnetic semiconductors, crucial to M-RAM technology. This group created a semiconductor that shows magnetic properties at room temperature and beyond. The excitement is palpable.
  • Hmmm...
    Left-pos, Left-neg, Right-pos, Right-neg.
    Four-states per bit (quit??)
    65,536 states per byte (quyte??)

    This is computing raised to the power of two...
  • Since the only reason I ever shut my computer down is because it locks up, I think I'll stick with volatile RAM, thank you very much. Software is going to have to get A LOT more stable before I'll be willing to change my mind.

    • the only reason I ever shut my computer down is because it locks up

      If you want to avoid this problem in the future, your best bet is to switch to a more stable operating system. Under MacOS X, which is BSD-based, I've had up-times of weeks. The only real reasons to reboot are the occasional kernel panic (once in a blue moon, usually after installing a badly written kernel extension) and the occasional updates to the operating system which change the kernel.

      I would say that by using a Unix-like operating system such as Linux, MacOS X, BSD, etc., you will avoid having your computer lock up due to a program crash. You just kill the locked-up process and go right along using your system. It is so awesome to be free of crashes and lock-ups.

      • <brag>
        Uptime in weeks?

        [tim@cr660477-a tim]$ uptime
        5:15pm up 118 days, 19:01, 6 users, load average: 0.00, 0.02, 0.00

        [tim@cr660477-a tim]$ cat /etc/issue
        Red Hat Linux release 7.1 (Seawolf)
        Kernel 2.4.2-2 on an i586

        </brag>
        • Very nice!

          I'm sure I could be up in that range also, but MacOS X is pretty young and it's had a couple of updates that made changes to the kernel and required a reboot. Once it settles down a bit I'm sure I could keep it up a similar amount of time.

          I think that I've managed to lock it completely up or get a kernel panic maybe twice in the past 9 months or so. Not bad for a brand new operating system.
      • The only real reasons to reboot are the occasional kernel panic (once in a blue moon, usually after installing a badly written kernel extension)

        Like I said...

        I run Linux at home, and I have managed to lock it up, and I don't just mean X, I know how to deal with that. Don't ask me how, but I've done it.

        At work, though, I don't have the luxury of choosing my OS, and the CAD package we use isn't available for anything but windows.

        I'm glad to hear that Macs are stable these days. I haven't used a Mac since OS8, and that POS went down harder, faster, and more often than even my old win95A box.

        I don't mean that as flamebait, that was just my experience.

        • Well, I agree that MacOS 8 could crash pretty good under certain circumstances, but that's all in the past now. MacOS X is stable, easy to use, extremely compatible, looks good, and has just about every advantage a Unix-like OS can have. It's a great marriage between BSD and Macintosh.

          I'm sure that it will only get better also. There are tons of developers churning out software for it, it's gotten rave reviews and people have taken notice. A lot of open source software has been checked and compiled and there are very few roadblocks to using most software packages for Unix-like OS's.

          Hopefully a lot of the one-platform programs will branch out a bit more and become available to alternative operating systems. With modern compilers and great frameworks out there it's getting to be easier and easier to produce multiple versions of a program which will run on a variety of systems.

  • permanent windows crash??? (Score:1, Funny)

    by Anonymous Coward
    Does this mean that when your windows machine crashes and you reboot it will still be crashed???
  • First, it isn't related to Quantum Computing. It's just a regular old nonvolatile memory.

    The technology works real nice. I did technology development project management for the Air Force in the late 80s on this and other wild-ass NVM technologies. MRM is very sound, just too pricey for commercial use yet. The problem is that the manufacturing economics combined with market perceived risk keeps it from prime time. Flash (the next nearest alternative) is more mature, more familiar and comfortable (derived from EPROM and E^2PROM technologies which are 25-plus years old) dispite its speed and endurance shortcomings.

  • RAM that maintains memory after shutdown

    I usually reboot my machine to clear the memory. While I there may be some benefits to keeping the memory state, like quick bootup, I boot in 20 seconds now ( 20 seconds from pressing the power button to the win98 hourglass disappearing) so that's not much of an issue for me. I would rather have the expected effect of a clean system startup on reboot than a 1 second boot time. Having the system remember bugs etc after a reboot would be awful, IMHO.
  • Why does that sound like the name of a cheesy early-nineties techno/hip-hop group? "Tonight on In Living Color, Jim Carey does something incredibly silly, and the musical stylings of SPINTRONIC!"
  • A bunch of people have posted silly questions about what happens if they get a crash or a virus or something.

    All you'd have to do is to have something on the motherboard that resets the memory.

    Then you'd have the normal shutdown/reset buttons, and then another button (or combination thereof) that would also wipe the memory in case of bad stuff.

    There, now how hard was that...
    • Awww, but that means we'll have to buy new cases! Cases with more buttons! Unless of course you have schematics for the button in question.

      Any technological advance not capable of fitting in my current case is not really a technological advance.
  • There are alot of uses for this .....

    Just think about handhelds that don't need battery backup's .... and have alot more storage....

    Also , if memory by this system is cheap enough, could it replace smaller hard drivers , on systems which access time is critical. Eg. Large Scale web sites , (search engines..etc..)
  • I'm just throwing this out as an idea...

    But could this be combined with trinary computing? You could consider whether something is not charged, and if it is, there is the spin, which would give you 3 states, perfect for trinary computing.
  • Was awhile back, but I read that the effect of electron spin was also being used to slow, and even stop light [hackensackhigh.org].

    Is the basic phenomenon analogous in these cases? It seems like this was also reported here on /., but I can't find it right now.

  • Reboot... (Score:3, Insightful)

    by TheShadow ( 76709 ) on Friday November 16, 2001 @01:12PM (#2575465)
    A lot of people are complaining that they only reboot their machines to "clear" the RAM. And they seem to think that if Windows crashed, this new MRAM stuff will cause their computer to be in a permanent crashed state.

    Well, obviously, computers making use of MRAM will have some way to purge the memory. And maybe the OS would set a flag on a normal shutdown that would tell the BIOS (or whatever it would be when this stuff comes out) that it can go ahead and just jump right to the OS (and the OS would clear that flag as it's first order of business). If the flag didn't exist, it would go through a boot sequence which involved loading the OS off a hard drive or whatever.

    But let's look at the advantages of having persistent RAM. If you have a journaling file system, the journal could be kept in memory without fear that it would be lost on a crash. When the system comes back up that data would be in memory and could then be used to repair the file system. Also, disk writes would be extremely fast because they could be cached and when the system is idle or when the disk is not busy, they could be written at that time instead of having to be written to a log that is physically on disk.

    Maybe, programs that are running could survive an OS crash because their state would be perfectly perserved in persistent memory.

    And if CPUs had persistent registers... recovering from a power failure would be seamless.

    Just some thoughts.
    • Just a note but MRAM is probably going to be most used (and most useful) in embedded aplications like portable electonics and automobile parts. You'll note that Motorola got out of the general RAM business some time ago but has constant need for low power parts. RAM that doesn't require refreshing and continuous power draw is perfect for things like automobiles or PDAs or small embedded controllers. Obviously, it'll also likely be too expensive in the near term for general PC type usage until the technology is better refined.
    • And if CPUs had persistent registers... recovering from a power failure would be seamless.

      Not likely. Implementing memory this way is not at all the same as implementing real logic.

  • I don't like the security implications of this. Disk access is relatively easy to monitor, and one can shred files appropriately. But having to shred memory, as would be the case in a system with persistent RAM, sounds like a management nightmare.

    I mean, as things stand, one can at least be confident that a value stored in volatile RAM is irretrievably gone if the power gets cut.

    Would it be feasible to have the OS shred all memory granted to a process when the process exits?

  • WARNING: Anti-Microsoft comment below. If you hate such commentary, stop reading now. I don't want to hear the needless whinning about all the Anti-Microsoft commentary. Guess what? This is Slashdot! It's part of the culture here. Do go preaching Atheism in church! Don't go accusing Slashdot of being unbiased! Simple right?

    ---Commentary begins---

    My knee-jerk reaction to this is that this type of RAM will not compatible with any version of Windows. Microsoft Windows, by Microsoft's explicit advice, often requires a reboot (memory clearing) of the machine upon which the operating system is loaded. Very often, powering off is used as opposed to a simply "reboot" or "reset" since memory is sometimes retained after an instantaneous restart. Cold booting is often preferred and recommended. (Interestingly, Microsoft also recommends periodic re-installation of the operating system after formatting the drive... apparently, it's not only system RAM that is prone to corruption.)

    While it can be said that this is true of all PC operating systems, it can more accurately be said
    that it's "less true" of other PC operating systems.

    Essentially, since Windows relies on the "clean machine" approach to efficient running, this memory technology is unsuitable for use with Windows without a "clear memory" switch.

    Pushing forward with the notion of "clean hard drives" wouldn't it be great if Windows Hard Drives came with an instant re-format feature?
    • SDRAM is also slightly persistant. Just rebooting doesn't necessarily clear your ram. In an embedded system I'm working on now, using industry standard PC133 dimms, I can power off, wait 2 mins, power on, and the data is *mostly* still there. (a few bit errors here and there, etc)

      One kinda cool (mis?)use of this feature is with FreeBSD's 'dmesg'. 'dmesg" shows the boot up log of the system. (kernel messages, etc). If you reboot, and the pointers still look valid, dmesg will show you the log messages as far back as the buffer will allow, sometimes spanning 2-3 boots.

      Most OS's have a "zero on allocate" method, where before they hand out any RAM to any process where it matters, they zero it. This is also an important security feature - suppose on a multi-user system, I open my e-mail program and send off a nice private e-mail and close it. Do I want you to be able to malloc() 256MB, and look through it to find my e-mail still sitting around? No. Before the OS hands out ram to a process, it usually zero's it. (note, malloc followed by free followed by malloc isn't usually zero'ed, it's assumed that within the same process, you'll wipe things out yourself if you really want it secure.)

      In any case, this isn't an issue at all. When you boot up ANY pc right now, it's not all zero'ed out, and OS's don't expect it to be. Rebooting things to cure problems is fixing things you put in RAM that got corrupted, as well as logical errors (the system is confused by something, etc).
  • A teaching assistant (grad student) at my University was hired by the National Institute of Standards after graduation to work on quantum computing methods. According to him, they have a pretty complete theory, and have obtained some fairly large grants to actually put that theory to work. Some of the things he talked about sounded really incredible.

    I found a Scientific American article from 1996 which details some of the their work, as well as the work of others, plus a lot of useful links.

    http://www.sciam.com/explorations/091696explorat io ns.html

    I remember first reading about using electron spin in quantum computing way back in 1994, in a NY times science edition.
  • There's a company called Micromem Technologies, Inc. [yahoo.com] that is nearly ready to produce the non-volatile memory that we're all talking about. Follow the link and read their yahoo profile.
  • RAM that maintains memory after shutdown sound interesting?

    Sound interesting? Hmmmm, no, actually it sounds just like the static memory in my BBC model B [zprod.org] (cerc. 1982), ok so I only had 32K of SRAM (and 32K of DRAM), but same idea (kind of).

    As for booting I also remember the BBC B could boot really fast. Using a trick that most slashdotter might find really interesting and have never heard of before, it's called putting the operation system on a rom. Neat yeah?

  • Today's computers rely on silicon-based microchips to process data in a binary form -- which allows only for "on" and "off" states. Quantum computers, however, will be able to examine data using spins, which has can have many different states.
  • How about using an etch-a-sketch for storage? Black dots mean 0, clear spaces mean 1. If you get nailed with a virus, you can erase the storage by picking up your computer and giving it a good shake. Oh, I guess that means simply moving your computer could create some hassles. Nuts... have to works the bugs out of the idea.
  • Sounds like it'd be nice to have suspension in ram, but getting rid of memory resident nasties could be a lot harder.

    Today (with Windows) most people are safe because they have to reboot every other day. :-)

  • Can you say "memory-resident virus"? Thought so.

    Yes, there are people who are clueless or ignorant enough NOT to have up-to-date virus shields. A virus that survives major system upgrades and disk sweeps would not be an impossibility. I shiver at the thought.

  • If you don't understand look up James Blish.
  • I'm a second-year graduate physics student, and although I haven't really embarked on any research projects as of yet (still taking the required coursework), I plan to study magnetoelectronics (also known by the catchy buzzword spintronics). I'll be working with C.L. Chien's Artificially-Structured Materials Laboratory [jhu.edu] at Johns Hopkins University [jhu.edu]. (The lab's webpage isn't that informative yet, but will be soon.)

    There are several groups working on spintronics-related research around the globe. You can check some of the research the spin-doctors are working on by looking at the Spintronics 2001 Conference [umd.edu] webpage. Some incredible results involved researchers injecting spin-polarized current into an LED and producing Circularly Polarized Light!!! Other researchers are trying to produced spin-transistors, to switch/amplify spin-polarized currents. Many of the recent challenges involve producing spin-polarized currents, finding materials that can transport electron-spin, and injecting spin-polarized electrons into semiconductors.

    The Chien group here at JHU has been the first to demonstrate experimentally the existence of a half-metal [jhu.edu]. Crystals of CrO2 have been shown to have spin-polarization of 96%. This was measured at the superconductor/ferromagnetic interface through Point-Contact Andreev Reflection (PCAR) techniques.

    I'll explain some of the current concepts of spintronics, but pardon any errors as I haven't really begun my research yet. The manipulation of electron spin is an extra degree of freedom that novel electronic devices can exploit. Spintronics has already, since 13 years after the discovery of GMR (Giant Magnetoresistance) in 1988, penetrated the technology industries (magnetic storage). It's rare for such new technology like this to be commercially available so soon after its discovery. Transistors were one such monumental achievement, the first Ge transistors were available within years of the transistor's invention.

    GMR is an effect that occurs with a normal metal film that is sandwiched between two ferromagnetic layers. Depending on whether the spins of the ferromagnetic layer are parallel or anti-parallel, a significant change of resistance is measured across the structure. A more useful device which extrapolates off this concept is a spin-valve This is the standard GMR trilayer, with an anti-ferromagnetic layer on the bottom. This layer pins the spin of the bottom Ferromagnetic layer. The top ferromagnetic layer can then float, and have it's spin affected by the external magnetic field. This in turn creates a magnetic-field-dependent resistance across the device. Sensitive measurements of the magnetic field, obtained by measuring resistance, can be obtained in this manner .This magnetic-field-dependent resistance is known as Magnetoresistance. This concept, in a fundamental sense, is how the newer GMR-based read-heads on high-density hard drives operate.

    Another similar device is the Magnetic Tunnel Junction . This is similar to the GMR trilayer, but an insulator film is sandwiched between the ferromagnetic layers, instead of a normal metal. Current can then tunnel through the device, again dependent on whether the spins are parallel or anti-parallel in the ferromagnetic layers. The tunnel junction is the fundamental concept at the core of the MRAM's.

    Another exciting area of research with spintronics that I haven't heard anybody on slashdot mention yet is quantum computing. Electrons are spin-1/2 fermions, and hence have two distinct eigenstates of the Spin operator (the eigenstates are usually called "spin-up" and "spin-down"). This makes them perfect candidates for representation of quantum bits (qubits) for potential quantum computation. Some groups are working on this idea, by studying interactions of quantum dots for instance.

    Overall, this is a budding field that has already impacted the technology industry in it's scant 13 years of existence. Expect many more interesting and potentially groundbreaking discoveries to occur. But then again, I'm spin-biased. :-)

  • Sounds a lot like the write-only drive I developed in the 80's while a physics student in college. It used the Pauli Exclusion and Heisenberg Uncertainty principles to store tremendous amount of information. Problem was, I couldn't get the informaton back out.

    A guy called after reading our April edition of our user's group newsletter and asked if I had patented the idea and wondered if we could send him a prototype. Shortly thereafter, he received a bakelite case with a SCSI cable coming from it. He hooked it to his Mac. Took the guy three phone calls before he understood it was all a joke.

    Can I claim prior art here?
  • There will be a spintronics symposium at the upcoming Fall 2001 meeting of the Materials Research Society meeting. It appears that about half of the talks will be about MTJs (the type of structures used in TMR MRAM) and another really big block about these dilute magnetic semiconductors. These are not new per se, but have been strongly revived by spintronics research. Especially important is the development of III-V and Group IV magnetic semis, primarily the result of dilute manganese doping. Really exciting stuff nowadays.
  • What i've always wondered about quantum computers is how the devil you would measure them.

    For those that don't know, nothing is ever finite in quantum mechanics, only probable. (See heisenbergs uncertainty principle).

    also by measuring the system by some method you are interfering with the system. And thus how do you know whether the result is the result or a product of your interference.

    Now if you were using a lot of electrons on a surface (don't ask me how) all in the same starting spin state, then you performed an operation on them you could then measure the macroscopic properties of your sheet of electrons. IE the bulk magnetisation (see ESR spectroscopy), but single electrons would be impossible to discover with current theory.

    The other complication is that the electron spin states are degenerate (have the same energy)in the free state and in the abscence of an external magnetic field.

    Thus to measure a change in spin state you would have to stick the quantum device in a very large amgnetic field (5 Tesla or greater). This requires a large super conducting magnetic cooled to the temperature of liquid helium.

    Therefore this whole quantum Computer thing is a fairly difficult to achieve and willnot happen over night and probably not until someone comes up with a different theory to current QM theory, which explains in more detail the actions of small particles.

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