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]

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

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]

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.

Perhaps I am wrong



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

Perhaps I am wrong



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

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

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]

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.

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

 

[f95toli]

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...

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]

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

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]

Umm, MRIs use superconductors, which is a very quantum phase. That example holds.

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 https://www.physicsforums.com/showthread.php?t=248487

Nuclear power would be a not-so-obvious application; nuclear decay is an intrinsically-quantum mechanical phenomenon, and you need to know about collision cross-sections etc. to control reaction rates.

The next generation of nanotechnology, quantum computers, etc. might turn out to be quite fun too

 

[alxm]

Nuclear power would be a not-so-obvious application; nuclear decay is an intrinsically-quantum mechanical phenomenon, and you need to know about collision cross-sections etc. to control reaction rates.

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/cpquery/?&dbname=cp110&sid=cp110susc7&refer=&r_n=sr335.110&item=&sel=TOC_278710&

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

 

[Galteeth]

“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&

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

Well, on the plus side, a lot 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)

 

[Redbelly98]

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

 

[vanesch]

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 Schrödinger 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 ?

 

[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)

 

[alxm]

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

No. You can do lots of chemistry without solving the Schrödinger equation, but there is no 'semiclassical model' of chemistry. Chemical theory without QM would mean going back to Lewis dot-structures. That's high-school chemistry.

All newer models than that: MO theory, Valence-Bond theory, Orbital hybridization, VSEPR, Frontier MO, etc, (which is stuff they teach to chemistry undergrads in their first year or thereabouts) are based directly on quantum mechanics.

(Add to that, all the methods that involve directly solving the S.E..)

Chemistry without quantum mechanics is like pre-Newtonian physics. A set of semi-empirical rules without any coherent unifying theory behind it all.

 

[PhaseShifter]

VSEPR based on QM? Since when?

It's basically just Lewis dot structures in 3-D, arranged with the maximum possible distance between electron pairs.
Hybridization is assigned based on the number of sigma bonds + nonbonding pairs, not actual combination of atomic orbitals to form hybrids.

 

[alxm]

VSEPR based on QM? Since when?

Since the start. (R. J. Gillespie, "The valence-shell electron-pair repulsion (VSEPR) theory of directed valency", J Chem Ed, v40, p295-301).

It's basically just Lewis dot structures in 3-D, arranged with the maximum possible distance between electron pairs.

The rationale for that separation being electrostatic repulsion and the Pauli exclusion principle.

Hybridization is assigned based on the number of sigma bonds + nonbonding pairs, not actual combination of atomic orbitals to form hybrids.

The point being.. that it's therefore not based on quantum physics? You'd be doing Pauling a grave injustice claiming that.

QM provided the theoretical basis for developing all these concepts (and to mention some more: Solid definitions of electronegativity, chemical potential, etc). As I said, this stuff is often taught to freshman chemists, and then without the theoretical justification. But that doesn't mean one should assume that there isn't one.

 

[Redbelly98]

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 ?

Good point. Otherwise, I could argue that a light bulb is related to blackbody radiation, hence QM.

 

[Phyisab****]

Spintronics. Look it up.

 

[gomunkul51]

Spintronics? The question was: "What technologies based on quantum mechanics affect our daily lives?" Personally the only person I know who's life is being affected by Spintronics is my buddy who does research in the field at the university ;)

 

[gomunkul51]

As all of us know, computers affect our lives greatly. All modern microprocessors are very much affected by quantum mechanics (quantum tunneling) and we are near the limit of current silicon based transistor functionality.

 

[meBigGuy]

I'd vote for LED's as the simplest example of everyday consumer technology that required quantum mechanical expertise to discover and perfect.

 

[Xtyn]

Isn't the photoelectric effect a quantum effect?
Digital cameras and laser printers use the photoelectric effect, therefore, they are based on quantum physics.

Am I wrong?

 

[NegativeDept]

Isn't the photoelectric effect a quantum effect?

Yes! I think that's a good example. Theories by Lenard, Planck and Einstein about the photoelectric effect were predecessors of QM and the modern use of the word `quantum.'