back to article Boffins hampered by the ampere hanker for a quantum answer

The search for a new ampere standard has moved a little further on, with a paper claiming that accurate quantum-level electron generation is feasible. Hans Schumacher of the Federal Institute of Physical and Technical Affairs (PTB) in Braunschweig, Germany, and a group of collaborators, say they have been able to demonstrate “ …


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  1. Eponymous Cowherd

    Nail that Electron

    "A quantum-based standard would be preferable, but it's proved elusive because counting individual electrons is prone to error."

    They just need to recalibrate their Heisenberg compensator.

    1. FrankAlphaXII

      Re: Nail that Electron

      Have to be careful with that. Otherwise you'll blow out a good portion of your EPS grid the first time you use the transporter afterward and noone wants that, especially not anyone who might be caught in the buffer at the time.

      Damn, I know way too much about that fictional universe.

      1. Trevor_Pott Gold badge

        Re: Nail that Electron

        Reroute the EPS flow through secondary relays and cycle the pattern through the cargo pad buffers. Once there, you should be able to get a lock on the pattern in the cargo pad buffers by using a second annular confinement beam.

        Just make sure you track both beams and re-integrate them, otherwise you'll clone whatever's in the buffer.

  2. umacf24

    Lovely subhead. Would read again. 5*

  3. Allan George Dyer Silver badge

    So we need to hunt down small things that move unpredictably. Sounds like a job for Schrödinger's cat!

  4. dervheid

    You WHAT?

    I = V/R


    1. This post has been deleted by its author

    2. Suricou Raven Silver badge

      Re: You WHAT?

      But R=V/I

  5. ElectricFox

    I always thought it odd that the Ampere is a base SI unit. It's considered a flow rate of one coulomb per second. Surely, the coulomb should be considered the base unit here?

    Any explanation would be greatly appreciated...

    1. vagabondo

      > It's considered a flow rate of one coulomb per second

      (I am not sure if you are joking, senile, or did not take science at school.)

      It could be if a coulomb could be measured reliably. Actually the coulomb is an SI derived unit (Ampere second).

      1. Tim Bergel

        If I understand this correctly, what they are doing here is coming up with a way of counting electrons accurately. As a coulomb is equal to the charge on a fixed (& very large) number of electrons, surely this will lead to defining the ampere in terms of the coulomb?

        1. ElectricFox
          Thumb Up

          Thanks for that. I was just pointing out that the coulomb would make a better base unit than the ampere. It's interesting that they're striving to define the kilogram by counting standard isotope silicone atoms much in the same way counting electrons could give a better definition of the coulomb...

    2. tojb

      a little harsh

      "joking or senile" seems a bit excessive.

      Perhaps the point being made is that its easier to count electrons (eg Millikan's oil drop experiment, which wasn't that easy at the time but should in some form straightforward be today) and measure their charge statically. Then you just need mu_0 and epsilon_0, bingo, Ampere's law gives you the definition of an Amp as quoted. I'm guessing that this plan is why the definitions were set up the way they were.

  6. James Boag


    So not only am i being over charged by my power company but im being billed for electrons that may or may not even arrive at my house, Time to call trading standards me thinks !

    1. monkeyfish

      Re: Hmmm

      The electrons will almost certainly never arrive at your house, what with them wobbling back and forth all the time. Power will arrive at your house, but the electrons you started with are still the ones you've got today.

      1. Patched Out

        Re: Hmmm

        Only if the DC offset of the AC waveform is perfectly zero.

      2. Primus Secundus Tertius

        Re: Hmmm

        How can you tell? Electrons are indistinguishable.

        1. Naughtyhorse

          Re: Hmmm

          by indistinguishable I take it you mean unique?

          1. Naughtyhorse

            Re: Hmmm

            So that will be 2 of you that haven't heard of Pauli.

  7. JimmyPage Silver badge

    Is this the 21st Century equivalent

    of counting how many angels can fit on the head of pin ?

    1. Yet Another Anonymous coward Silver badge

      Re: Is this the 21st Century equivalent

      Except that people are being charged for the number of angles delivered

    2. Ponmyword

      Re: Is this the 21st Century equivalent

      One of Feynman's postulates was that there is only one electron in the universe, and it is jolly busy.

  8. John Smith 19 Gold badge
    Thumb Up


    The trouble is 1 electron = 1.6 x 10^-19 Coulombs

    So roughly you need to count on the order of 6.25 x 10^18 electrons.

    Even at 1 GHz that's 6.25 x 10^9 seconds or 199 years.

    So probably going to mass produce this device. 1000 of them should knock it down to well below one year.

  9. Naughtyhorse

    quantum metrologists

    here we go!

    Man made quantum warming....

    (should have gone to specsavers)

  10. RobHib

    Redefining the Ampere standard biggest change since Josephson got in on the Volt act.

    ...the amount of charge flowing per second through two infinitely long wires one meter apart,..

    Well, perhaps we should put Maxwell's demon down amongst the electrons to count 'em. ;-)

    Seriously, that definition of the Ampere always seemed to be messy to me. Seems that if the standard ampere is changed then there'll have to be some tinkering with the Volt definition too as it is also defined in terms of the same parallel wires in free space as well as a more practical/measurable (and precise) standard--that's now defined by the Josephson junction (which is some 4 orders of magnitude better than the old Weston cell standard of 1.434 volts).

    If it can be done then it makes sense to count electrons this way as it does to measure frequency from a Josephson junction for the Volt standard (frequency [time] being the most precise measurement standard we have devised so far). Hopefully, come the change, this would put Ampere standard on par with that of the Volt.

    Except for the Ampere measurement, I'd reckon there'd be no change to the related maths (as with the Volt, the parallel wires defn. would also remain).

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