# What technologies based on quantum mechanics affect our daily lives?

1. Sep 16, 2009

### Galteeth

I know MRIs. It seems that cell phone towers use superconductivity. What are some others?

2. Sep 16, 2009

### alxm

Define 'based on'?

You can get extremely specific, as in devices that directly utilize a quantum-mechanical phenomenon in a central capacity, such as MRI.

You can also be extremely broad, as in the fact that all the fundamental theories of chemical bonding and structure beyond the high school level are based directly on quantum mechanics. -It'd be impossible to say what the state of chemistry would be like in a world where Pauling's "The Nature of the Chemical Bond" and the theories presented would never have existed... As it turned out, the entire science of chemistry is just a specialized field of applied quantum mechanics.

I don't know that cell phone transmitters use superconductors, though? Why would they need that?

3. Sep 16, 2009

### kanato

Pretty much every piece of consumer electronics. Anything using permanent magnets, semiconductors or lasers (like CD/DVD players).

4. Sep 16, 2009

### Staff: Mentor

There are lots of uses of QM in modern electronics, but your two lead-off examples make no sense to me. If you google electronics quantum tunneling, you will get a lot more real examples.

5. Sep 17, 2009

### Galteeth

Perhaps I am wrong

http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=919285

6. Sep 17, 2009

### sokrates

Transistor

which is the principal actor of ALL modern electronic devices. No exceptions. You probably own a a couple billion of those these days...

Although the initial model proposed by Schokley did not include any quantum mechanical analysis, all the theory is based on some sort of a "band structure" , derived from quantum mechanics, and of course the effective mass theorem - another simplification from quantum mechanics.

7. Sep 17, 2009

### Staff: Mentor

Weird. Cryogenic does not necessarily mean superconducting, first of all. But to be honest, those links a) look strange, and b) are beyond my experise to comment on. I'll report this thread to ask for help from the physicists here at the PF...

8. Sep 17, 2009

### sheaf

I'm guessing these are HTS (High Temp Superconducting) components used in mast head amplifiers. In designing the receiver subsystem at the cellular base station, you put some gain as close as possible to the antenna, by siting an amplifier at the top of the tower. This provides better overall signal to noise ratio since noise generated in the downstream components doesn't get amplified. The mast head amp uses a filter to provide some rejection of unwanted bands. It looks from the links as though HTS based filter components are being trialled in mast head amplifiers. As far as I know, they're not in widespread use yet....

9. Sep 17, 2009

### nnnm4

Umm, MRIs use superconductors, which is a very quantum phase. That example holds. I don't know about antennae.

10. Sep 17, 2009

### f95toli

Superconducting filters have been used commercially in base stations for a few years, although they are not in widespread use yet (but as far as I understand we are still talking about thousands of installations in total). I'd say the main reason you don't hear much about them that the companies that sell them have learned the hard way NOT to use the fact that they use superconductors as their main "selling point". Note that I am not saying that they are hiding the fact that they use superconductors, but they've realized that performance is what counts.

The biggest seller of filters is STI

http://www.suptech.com/home.htm [Broken]

There are also a few commercial installations of HTS components in the power grid (fault current limiters etc).

Last edited by a moderator: May 4, 2017
11. Sep 17, 2009

### ZapperZ

Staff Emeritus
Your iPod, iPhones, computer chips, etc... etc.. Modern electronics was given birth by the invention of solid state transistors, and that's based on quantum mechanics. So look around you, and practically everything that you see is either a direct application of QM, or was manufactured using the capabilities made possible by QM.

Zz.

12. Sep 18, 2009

### humanino

Physics Forums !

13. Sep 18, 2009

### alxm

MRI is entirely quantum mechanical. It all works by flipping nuclear spins that've been Zeeman-split with a strong magnetic field, often using a sequence of pulses to manipulate the evolving mixed state.

The superconductors are somewhat incidental - they're just for creating the magnetic field. The first NMR experiments were done with ordinary magnets. The very first successful NMR experiment used a big magnet that'd previously been used to help discover the muon.

14. Sep 22, 2009

### muppet

15. Sep 22, 2009

### alxm

Ah, I'm not so sure of that? I think it's reasonable to assume nuclear power could've been developed on a purely empirical basis. Probably not developed as far, and with a heck of a lot more supercriticality accidents on the way.. But at least rudimentary nuclear power would've probably happened?

Neutron capture was discovered empirically (was that Curie?) and so was the effect of slowing the neutrons down. (Fermi.)

Famously, the reaction rate at Chicago Pile-1 was ultimately controlled by a guy with a fire-axe.

16. Sep 22, 2009

### ViewsofMars

“The budget request included $407.3 million in PE 61153N for defense research sciences programs. The committee recommends an increase of$1.5 million in PE 61153N for research on quantum computing and quantum mechanics that can support efforts to enhance Navy sensor and communications systems. The 2004 National Research Council study entitled Advanced Energetic Materials' characterized the U.S. effort on research and development of energetic materials as suboptimal,' but stated that the materials are `a key component of the nation's defense strategies.' To help address this identified gap, the committee recommends an increase of \$1.5 million in PE 61153N for basic research on energetic materials.”
(Senate Report 110-335 - NATIONAL DEFENSE AUTHORIZATION ACT FOR FISCAL YEAR 2009)
http://icreport.loc.gov/cgi-bin/cpquery/?&dbname=cp110&sid=cp110susc7&refer=&r_n=sr335.110&item=&sel=TOC_278710& [Broken]

I'm still thinking about the money that goes into 'defense research science programs' that are meant to protect me.

Last edited by a moderator: May 4, 2017
17. Sep 22, 2009

### Galteeth

Well, on the plus side, alot of that teach that's developed for the military winds up being useful in ways that don't kill people (like when Al Gore invented the internet)

Last edited by a moderator: May 4, 2017
18. Sep 24, 2009

### Redbelly98

Staff Emeritus
Atomic clocks. And, by extension, GPS for example.

19. Sep 24, 2009

### vanesch

Staff Emeritus
Maybe an interesting derivative of the question of the OP would be:

what technologies *are absolutely dependent on a thorough understanding* of quantum mechanical theory in order to be able to be designed ?

Because of course most of chemistry is "quantum mechanics", but one can do a lot of chemical technology without having to solve explicitly any Schrodinger equation, but base oneself on a semiclassical model and empirical data.

The same goes for micro electronics: although the transport properties of charges in semiconductors are explicitly quantum-mechanical, most intermediate-level courses on semiconductors use the semiclassical approach without needing explicit quantum-mechanical theory.

Even lasers can be understood using a semiclassical theory of lasers, once you know a few basic constants of your medium.

Almost all nuclear technology is based upon a "classical" view and empirical cross sections - with one exception: that is neutron scattering and derivatives (spin echo and so on).

So the question might rather be: for what technology does one really need to dig into quantum-mechanical theory as part of the design process ?

20. Sep 25, 2009

### PhaseShifter

Maybe we don't see a daily impact from these, but:

Scanning tunneling microscopy
SQuID magnetometers
Electron paramagnetic resonance spectroscopy
Nuclear magnetic resonance (spectroscopy or imaging)