# Making computer chips requires quantum mechanics math? **URL:** \ **Category:** Factual Questions\ **Created:** [November 24, 2011, 8:46am UTC](https://boards.straightdope.com/t/making-computer-chips-requires-quantum-mechanics-math/603963 "2011-11-24T08:46:26Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Hail\_Ants](https://avatars.discourse-cdn.com/v4/letter/h/dc4da7/32.png) [@Hail\_Ants](https://boards.straightdope.com/u/Hail_Ants)\ **Post date:** [November 24, 2011, 8:46am UTC](https://boards.straightdope.com/t/making-computer-chips-requires-quantum-mechanics-math/603963/1 "2011-11-24T08:46:26Z")
At the end of a recent Nova about physics they made mention of this. It was typical, end of the story, oh the timeless wonder of it all, fluffy-speak, but still. They sort of implied that quantum mechanics equations are actually needed/used in the designing and/or manufacturing of today’s microprocessors, and that without it they could not be as advanced as they currently are. Is this even remotely true? I found it wonderfully awesome to read years ago that GPS receivers actually contain Einstein’s formulas and would be off by hundreds of yards if they didn’t. I also know enough about relativity to be able to get my head around why that is. But I never thought quantum mechanics had any practical use in today’s world. Not dissing it at all, just thought Star Trek was still the only place that actually used a tachyon pulse (for everything!) ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [November 24, 2011, 10:35am UTC](https://boards.straightdope.com/t/making-computer-chips-requires-quantum-mechanics-math/603963/2 "2011-11-24T10:35:31Z")
Well, yes, for a few reasons, first among them being that we use light to etch the circuit designs into silicon and light obeys fundamentally quantum laws. Another quantum effect we have to deal with in modern microprocessor design is electron leakage through ‘closed’ gates due to quantum tunneling, whereby an electron or something like an electron has a certain chance of being able to ghost right through a wall, that chance being dependent, in part, upon how thick the wall is. Once you’re down to transistor sizes of 25 nanometers, gates can be as small as 1.2 nanometers, which is certainly thin enough for electrons to tunnel right through unless the design explicitly makes tunneling less likely. For reference, 1.2 nanometers is less than a thousandth the size of a red blood cell; we started making gates that size around 2006, and by 2008 they were somewhat old-fashioned. Too big, you know; gotta keep shrinking the process size. ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [November 24, 2011, 10:58am UTC](https://boards.straightdope.com/t/making-computer-chips-requires-quantum-mechanics-math/603963/3 "2011-11-24T10:58:20Z")
Also transistors themselves rely upon quantum mechanical principles. Unfortunately I can’t quite remember the explanation for this – something to do with movement of _positive_ charge and not being able to account for this under classical electrodynamics? “Quantum-” is quite a buzz word at the moment, and evokes various sci-fi images, but the core QM is as old as the hills… ---
**Author:** ![Half\_Man\_Half\_Wit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/half_man_half_wit/32/21766_2.png) [@Half\_Man\_Half\_Wit](https://boards.straightdope.com/u/Half_Man_Half_Wit)\ **Post date:** [November 24, 2011, 11:16am UTC](https://boards.straightdope.com/t/making-computer-chips-requires-quantum-mechanics-math/603963/4 "2011-11-24T11:16:20Z")
An electronic element that’s very concretely quantum (if such a thing can be said) is the [tunnel diode](http://en.wikipedia.org/wiki/Tunnel_diode), which for its functioning relies on the tunnel effect, i.e. that electrons can ‘cross’ regions they are classically forbidden to cross with a certain probability in quantum mechanics. But I don’t know that you’d find any of these in your computer (not because they’re terribly high-tech elements, quite to the contrary, they’re somewhat outmoded I believe, replaced by other devices capable of filling their function more efficiently). ---
**Author:** ![Hail\_Ants](https://avatars.discourse-cdn.com/v4/letter/h/dc4da7/32.png) [@Hail\_Ants](https://boards.straightdope.com/u/Hail_Ants)\ **Post date:** [November 25, 2011, 2:54am UTC](https://boards.straightdope.com/t/making-computer-chips-requires-quantum-mechanics-math/603963/5 "2011-11-25T02:54:23Z")
Wow! Just spent two hours bouncing around Wikipedia links. As said above, I have to keep reminding myself that quantum mechanics didn’t just spring up in the 1970s… ---
**Author:** ![Voyager](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/voyager/32/133_2.png) [@Voyager](https://boards.straightdope.com/u/Voyager)\ **Post date:** [November 25, 2011, 3:10am UTC](https://boards.straightdope.com/t/making-computer-chips-requires-quantum-mechanics-math/603963/6 "2011-11-25T03:10:42Z")
> [@Derleth](#): > > Well, yes, for a few reasons, first among them being that we use light to etch the circuit designs into silicon and light obeys fundamentally quantum laws. > > Another quantum effect we have to deal with in modern microprocessor design is electron leakage through ‘closed’ gates due to quantum tunneling, whereby an electron or something like an electron has a certain chance of being able to ghost right through a wall, that chance being dependent, in part, upon how thick the wall is. Once you’re down to transistor sizes of 25 nanometers, gates can be as small as 1.2 nanometers, which is certainly thin enough for electrons to tunnel right through unless the design explicitly makes tunneling less likely. For reference, 1.2 nanometers is less than a thousandth the size of a red blood cell; we started making gates that size around 2006, and by 2008 they were somewhat old-fashioned. Too big, you know; gotta keep shrinking the process size. I think you have a decimal point problem there - a gate can’t be smaller than a transistor. Feature sizes of products in active development are down to 18 nm ---
**Author:** ![JWT\_Kottekoe](https://avatars.discourse-cdn.com/v4/letter/j/3ec8ea/32.png) [@JWT\_Kottekoe](https://boards.straightdope.com/u/JWT_Kottekoe)\ **Post date:** [November 25, 2011, 4:44am UTC](https://boards.straightdope.com/t/making-computer-chips-requires-quantum-mechanics-math/603963/7 "2011-11-25T04:44:22Z")
> [@Voyager](#): > > I think you have a decimal point problem there - a gate can’t be smaller than a transistor. Feature sizes of products in active development are down to 18 nm Derleth is talking about the thickness of the gate, not its width. ---
**Author:** ![AaronX](https://avatars.discourse-cdn.com/v4/letter/a/7bcc69/32.png) [@AaronX](https://boards.straightdope.com/u/AaronX)\ **Post date:** [November 25, 2011, 6:04am UTC](https://boards.straightdope.com/t/making-computer-chips-requires-quantum-mechanics-math/603963/8 "2011-11-25T06:04:39Z")
> [@Half\_Man\_Half\_Wit](#): > > An electronic element that’s very concretely quantum (if such a thing can be said) is the [tunnel diode](http://en.wikipedia.org/wiki/Tunnel_diode), which for its functioning relies on the tunnel effect, i.e. that electrons can ‘cross’ regions they are classically forbidden to cross with a certain probability in quantum mechanics. But I don’t know that you’d find any of these in your computer (not because they’re terribly high-tech elements, quite to the contrary, they’re somewhat outmoded I believe, replaced by other devices capable of filling their function more efficiently). If you’re talking about tunneling, flash memory uses tunneling to store electrons as memory. ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [November 25, 2011, 6:32am UTC](https://boards.straightdope.com/t/making-computer-chips-requires-quantum-mechanics-math/603963/9 "2011-11-25T06:32:27Z")
> [@Voyager](#): > > I think you have a decimal point problem there - a gate can’t be smaller than a transistor. Feature sizes of products in active development are down to 18 nm If I’m wrong, [so is Intel](http://www.intel.com/cd/corporate/techtrends/emea/eng/209547.htm): > [@](#): > > Intel’s 65-nm transistors have a reduced gate length of 35 nm and a gate oxide thickness of 1.2 nm Unless I’m very much wrong, the ‘gate oxide’ is what’s on top of the source and drain terminals, and connects them when when the gate is on; it’s 1.2 nanometers _tall_ in the 65 nanometer process. > [@JWT\_Kottekoe](#): > > Derleth is talking about the thickness of the gate, not its width. Right. ---
**Author:** ![Voyager](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/voyager/32/133_2.png) [@Voyager](https://boards.straightdope.com/u/Voyager)\ **Post date:** [November 25, 2011, 7:15am UTC](https://boards.straightdope.com/t/making-computer-chips-requires-quantum-mechanics-math/603963/10 "2011-11-25T07:15:30Z")
> [@Derleth](#): > > If I’m wrong, [so is Intel](http://www.intel.com/cd/corporate/techtrends/emea/eng/209547.htm):Unless I’m very much wrong, the ‘gate oxide’ is what’s on top of the source and drain terminals, and connects them when when the gate is on; it’s 1.2 nanometers _tall_ in the 65 nanometer process. > > Right. Ah, your use of gate is ambiguous. I use it to refer to cells. But I’m neither a process person or a library person. Of course the stuff in the lab is a lot smaller than the stuff in production.