What is the smallest physically-possible voltage that can be detected or processed given the state of today's technology?

You can buy nanovoltmeters that will resolve a couple of hundred picovolts, if you're careful.

Superconductive SQUID detectors can measure a picovolt.

Single-electron transistors can sense, well, single electrons.

John

Go bugger yourself, you spamming pile of shit.

PMTs can be good enough to detect single photon events.

Oh my god please f*ck off from sci.physics. We do not want you.

Hmmm... I have a $35 digital multimeter that can measure exactly 0 volts!

Rick

No, it can't. It can display zero, even with some voltage at the input. The issues is the resolution of the meter. Even with the probes shorted, you will have some Johnson noise which is generated by the resistors in the input circuitry, if the meter is above absolute zero degrees. That voltage is too low to be displayed, but it is still there.

Just kill file the idiot. If no one replies, they will give up. Trolls thrive on attention, so you have to starve them.

Yeah, but to how many percentage accuracy?

John

But he asked a sensible question this time.

John

Never the less, into the binary bin with him I say !!

Rheilly P

Yeah, but when it's exactly zero volts, that what the $35 multimeter will display, so he wasn't incorrect.

;)

Well, but zero volts is ancient history, rather than a measurement. Which is why the people with brains invented optcal computers, flat sceeen hdtv debuggers, c++, distributed processing, blue ray, holograms, xml, usb, on-line banking, on-line shopping, on-line publishing, diigital-terrain mapping, post Ford Batteries, and self-assembling robots, rather than idiot physics anyway.

Is there any one in this group with the necessary scholastic qualifications to diagnose the reason this poster asks such esoteric questions

It probably needs someone from the astronomical and satellite-making communities (and maybe folk at Cern et al), who have necessarily to deal with the smallest detectable signals; and the answer will (a) probably have to do with the lowest-achievable noise (C --> Absolute Zero), and (b) change regularly as new technology is developed to see further back in space/time, and to detect smaller and smaller (etc) particles. To these folks, a photon or an electron is probably pretty loud.

The best I can suggest is to start with picovolts and work downwards, e.g. (from a quick google search):

Are yattovolts measured anywhere? I had not known of this unit until this question popped up, so I am already grateful for learning something new, even if its everyday usage is (for me) rather limited.

sci.physics appears not to be on the list. If it is a legitimate albeit esoteric question, I would have thought they would be the most likely to enjoy both the question and its answers. Though I have observed that as a general rule, people on newsgroups prefer questions that have answers that can be both definitive and short. Perhaps this is not one of those?

Richard Dobson

rickman wrote: > On Jun 1, 10:33 pm, ItsASecretDummy > wrote: >> On Mon, 01 Jun 2009 17:40:20 -0700, John Larkin >>

How exactly?

Jerry

aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah- ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah- ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah- ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah- ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah- ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah- ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah- ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah-ooh aah- ooh aah-ooh aah-ooh aah-ooh aah-ooh

Are there any devices that can detect, receive, record, playback, modulate/demodulate, transmit and/or otherwise process signals with peak-to-peak amplitudes around 1 femtovolt?

In comp.dsp GreenXenon wrote: (snip)

Since it is usually power, and not voltage, that is the limiting factor, it might be possible if the current is high enough.

If you go through a transformer, or a series of them, to get to a more usual voltage and current range, then it might work. I would say that it is likely not possible to measure femtovolts DC, but likely possible AC.

-- glen

He seems interested in the issues but confused about physical units.

I suppose I should get on with writing my book, to make all this stuff plain.

John