# 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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#### 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.

#### 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.

#### 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.

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

#### You WHAT?

I = V/R

Simples

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#### Re: You WHAT?

But R=V/I

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...

> 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).

#### 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.

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?

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...

#### Hmmm

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 !

#### 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.

#### Re: Hmmm

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

#### Re: Hmmm

How can you tell? Electrons are indistinguishable.

#### Re: Hmmm

by indistinguishable I take it you mean unique?

#### Re: Hmmm

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

#### Is this the 21st Century equivalent

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

#### Re: Is this the 21st Century equivalent

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

#### 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.

#### Impressive

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.

#### quantum metrologists

here we go!

(should have gone to specsavers)

#### 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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