Can I apply what I learn in quantum mechanics to electrical engineering?

[Boltzman Oscillation]

Are there any projects I can build? What are the applications of QM in electrical engineering?

 

[analogdesign]

QM is the very bedrock of integrated circuits. The Quantum Theory of Solids that underpins all semiconductor technology is entirely based on QM. In fact, the very concept of a semiconductor makes no sense using classical models. So, if you do work that requires you to get down to the core principles of devices such as integrated circuits or solar cells or the like, you need QM.

So, most research in electronic materials requires QM. Also, the devices are getting so small doing accurate device simulations requires QM. Lasers are another QM phenomenon, so doing laser research requires QM (many interesting lasers are built using semiconductors these days so you're using QM twice). There are other applications.

 

[ZapperZ]

Are there any projects I can build? What are the applications of QM in electrical engineering?

This is rather odd. Pick up a semiconductor. We understand its behavior due to QM. I'm sure you are fully aware what semiconductors are you used in electrical engineering. If not, rip apart one of your electronic devices and look at your microchip.

Zz.

 

[Qurks]

Not really, not unless you're developing semiconductor devices. No one really uses QM when doing IC design. So in principle to understand why devices work QM is interesting but unless you're doing R&D, it doesn't matter. I actually talked to a guy leading IC development of a major company and he said they don't even touch QM, they purely use the standard device models.

 

[analogdesign]

Not really, not unless you're developing semiconductor devices. No one really uses QM when doing IC design. So in principle to understand why devices work QM is interesting but unless you're doing R&D, it doesn't matter. I actually talked to a guy leading IC development of a major company and he said they don't even touch QM, they purely use the standard device models.

I get what you're saying, but I think you're setting a pretty high bar. If what you mean by "use QM" means sit at a desk and solve Schrodinger's equation or run QCD simulations, then yes, I would say that IC designers don't use QM.

On the other hand, we deal with a lot of very QM effects (such as gate tunneling). We have simplified models to deal with them, but that doesn't change the fact that the devices act in a QM way.

If the bar for working with QM is actually solving QM equations, then even most High-Energy Physicists don't use QM!

 

[Qurks]

I get what you're saying, but I think you're setting a pretty high bar. If what you mean by "use QM" means sit at a desk and solve Schrodinger's equation or run QCD simulations, then yes, I would say that IC designers don't use QM.

On the other hand, we deal with a lot of very QM effects (such as gate tunneling). We have simplified models to deal with them, but that doesn't change the fact that the devices act in a QM way.

If the bar for working with QM is actually solving QM equations, then even most High-Energy Physicists don't use QM!

Then practically speaking, QM isn't necessary or useful to electrical engineers, which is what the OP asked. Even the semiconductor physics/devices books I have looked at don't really use QM. I'm curious if device engineers even use it in its raw form.

 

[Joshy]

All of my modules covering semiconductors and integrated circuits had coverage on quantum mechanics. I agree we didn't have to go home and solve Schrodinger's equation or use commutators, but there would at least be a chapter, a large section, an entire lecture or two, or an assignment where you'd try using your classical understanding on something with a very small channel- students walked out of the classroom with at least a vague conceptual understanding, and those who understood it better with more detail could often compensate for these effects better in their design rather than running some fine parametric sweep on a simulation. Pierret's book definitely has something on it and that book is a classic... I've seen it at so many universities and while visiting other laboratories, that I'm sure a good number of people would recognize it here. I don't recall any specific call out for it in Baker's book CMOS although I do remember seeing comparisons or explanation on using long channel designs (as opposed to small channel).

Can you apply it? I would certainly think so, or at least these concepts have appeared many times in the classroom and at the early stages of my career. It's not so rare that it would be useless to know although I'm agreeing you wouldn't need a super detailed/thorough understanding... I think it's possible to get by without knowing it although it kind of seems more like luck or just sweeping without understanding (not very good practice in my opinion).

 

[ZapperZ]

The problem here is the vague meaning of "applying" what one learns in QM. Does using a solid-state transistor qualify as "applying" QM?

One doesn't need to know QM to make use of the fact that semiconductors have band gaps, even though the concept of "band gaps" came directly out of solid state physics's application of QM to the semiconductor band structure. You also don't need to know about tunneling phenomenon to make use of a tunnel diode, but the device clearly make use of a quantum mechanical phenomenon. Heterodyne mixer? Same thing.

I would even say that if you get a bunch of LEDs of different colors, you can even perform an experiment easily where you end up getting Planck's constant directly!

Zz.

 

[Qurks]

The problem here is the vague meaning of "applying" what one learns in QM. Does using a solid-state transistor qualify as "applying" QM?

One doesn't need to know QM to make use of the fact that semiconductors have band gaps, even though the concept of "band gaps" came directly out of solid state physics's application of QM to the semiconductor band structure. You also don't need to know about tunneling phenomenon to make use of a tunnel diode, but the device clearly make use of a quantum mechanical phenomenon. Heterodyne mixer? Same thing.

I would even say that if you get a bunch of LEDs of different colors, you can even perform an experiment easily where you end up getting Planck's constant directly!

Zz.

Actually, it's an interesting question - out of the physics that exists, what percentage is actually used? In particular, what aspects of the theory actually come into play when it comes to making useable things?

I suspect at best the highly theoretical subjects provide some idea why something works but separate models(maybe even based upon experiment) are created to actually describe things. The bandgap example is perfect.

QM is cool but how much application it has in its raw form? IDK, QED and QFT seem even more useless.

 

[ZapperZ]

Actually, it's an interesting question - out of the physics that exists, what percentage is actually used? In particular, what aspects of the theory actually come into play when it comes to making useable things?

I suspect at best the highly theoretical subjects provide some idea why something works but separate models(maybe even based upon experiment) are created to actually describe things. The bandgap example is perfect.

QM is cool but how much application it has in its raw form? IDK, QED and QFT seem even more useless.

The term "useless" is relative. It may be "useless" directly to everyday application, but it is not useless as in basic knowledge. And from these basic knowledge, another level of knowledge that bridge that to practical application. So these "useless" knowledge is in fact, the SEED of subsequent knowledge that leads to applications.

And let's not dismiss such things so easily. Back in the early 1900's, I'm sure people think all these talk about quantum superposition, etc.. have no clear application. Yet, we have seen how things that started out to not having direct application becomes the impetus for everything we use today. We know how to use proton beams and heavy ions for medical applications, and the use of muons for imaging not simply from trial and error, or from a dream. It came out of our intimate knowledge of elementary particles, and this includes QED and QFT.

BTW, you should open a text on condensed matter physics (which many people consider to be an "applied" physics field). It is full of QFT!

Zz

 

[Qurks]

Coming to think of this, I talked to a Professor who was a device engineer and he never used QM in anything he did. My impression from him was that QM is an unworkable model for anything which isn't trivial.

 

[analogdesign]

...the device clearly make use of a quantum mechanical phenomenon. Heterodyne mixer? Same thing.
Zz.

Great post, but I'm curious. How is heterodyne mixing a quantum phenomenon?

 

[ZapperZ]

Great post, but I'm curious. How is heterodyne mixing a quantum phenomenon?

This is an example:

https://ieeexplore.ieee.org/document/1060994/

SIS tunnel junction is a clear quantum tunneling phenomenon. Brian Josephson won the Nobel prize for that discovery.

Zz.

 

[analogdesign]

This is an example:

https://ieeexplore.ieee.org/document/1060994/

SIS tunnel junction is a clear quantum tunneling phenomenon. Brian Josephson won the Nobel prize for that discovery.

Zz.

That's very interesting, but I will quibble. What you linked to is indeed a quantum device that is a way to generate a nonlinearity that is used for heterodyne mixing. The mixing itself, though, simply requires a nonlinearity (almost any will do, in my prelims on one of the questions the professor used a wire hanger). So I would submit that while the particular device is quantum the technique itself (mixing) is not. Otherwise, you could define something as prosaic as amplification as a quantum phenomenon because transistors exist (but so do tubes and transformers).