What technologies based on quantum mechanics affect our daily lives?

Galteeth

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

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?

kanato

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

berkeman

Your two examples are incorrect. Lordy. Please provide some links to what the heck you are talking about with them.

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.

Galteeth

Perhaps I am wrong



http://ieeexplore.ieee.org/xpl/freea...rnumber=919285

http://www.springerlink.com/content/h741867928v7j258/

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.

berkeman

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...

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....

nnnm4

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

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

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

ZapperZ

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.

humanino

Physics Forums !

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.

muppet

Quoting from http://www.physicsforums.com/showthread.php?t=248487

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.

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/cpqu...el=TOC_278710&

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

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)