Anti-phonon for Cooling
Curious
Is it possible to use anti-phonons for cooling the environment?
The quantum of heat is the phonon. An "anti-phonon" is simply a phonon
whose phase is reversed. Two phonons of opposite phases would cancel
each other. Right?
Uncle Al
Conservation of energy. A phonon is a quantized lattice vibration.
Annihalation of anti-phased phonons, if such a thing had meaning,
doesn't destroy the total energy. Positronium collapsing is an
energetic process - two 511 keV photons (and other paths depending on
initial spin state). A nulled interferometer (e.g., LIGO) doesn't
destroy its lasers' energy, it redistributes it.
--
Uncle Al
http://www.mazepath.com/uncleal/qz.pdf
http://www.mazepath.com/uncleal/eotvos.htm
(Do something naughty to physics)
Jacques Lavau
Well ! How do you produce and handle them ?
It is easy to consider and write something about phonons.
It is quite another damn thing to master, produce, direct them
individually, with a frequency, a phase, a direction, so on...
Are you a Maxwell demon, you ?
How do you consider the life-time of a phonon in a crystal, between
creation and annihilation ? What do you consider as a measuring device,
in order to copy an existing phonon, and to emit the right antiphonon ?
Well ! A pretty good troll, indeed !
--
La science se distingue de tous les autres modes de transmission des
connaissances, par une croyance de base : nous croyons que les experts
sont faillibles, que les connaissances transmises peuvent contenir
toutes sortes de fables et déerreurs, et qu=92il faut prendre la peine de
vérifier, par des expériences.
-- Jacques Lavau (retirer les anti et les spam pour le courriel)
http://perso.club-internet.fr/lavaujac/
Igor Khavkine
As far as I know, there is no quantum of heat. Heat or temperature
are statistical phenomena due to thermal (read more or less random)
motion of a large number of particles.
Phonons are quantums of lattice vibrations and are their own anti-particles,
just as photons are also their own anti-particles.
Phonons are indeed waves, and at least classically it is possible to
cancel one wave with a wave with another wave of the same amplitude
but out of phase by pi (or different by a factor of -1). However, this
property is fairly useless for the purposes of cooling. Even if you were
able to cancel out all phonon noice thermal motion of electrons and spins
would still be present. Besides, trying to remove all phonon noise
using descructive interference is like trying to dim the Sun by sending
specially modulated photons at it. It's not going to work.
Hope this helps.
Igor
jdff
k_ig...@lycos.com (Igor Khavkine) wrote in message news:<f1ac2e6e.04051...@posting.google.com>...
> curious...@yahoo.com (Curious) wrote in message news:<34a4f456.04051...@posting.google.com>...
> > Is it possible to use anti-phonons for cooling the environment?
> >
> using descructive interference is like trying to dim the Sun by sending
> specially modulated photons at it. It's not going to work.
>
> Hope this helps.
>
> Igor
OK, practically no, but not quite as stupid as it sounds at first.
Actually, you can cool things by shining light at them - optical
molasses is quite a common technique.
But also, if the object you are trying to cool has been set up with a
population inversion of states which can EM couple, it is a laser.
Fire one photon in, get two photons out, target loses net energy.
In a crystal lattice at low temperature, the phonon spectrum can show
distinct spectra. And I seem to remember reading some experiment that
showed population inversions in phonon states, although I don't have a
reference to hand. They were suggesting that their device could be
used as a "phonon laser" to probe crystal lattice defects at low
temperatures
Certainly experiments have been performed that have demonstrated
phonon ballistic transport (i.e. mean-free path of phonon > size of
test-chip) in GaAs/AlGaAs structures at 30 mK temperatures, which
means that phonon two-slit diffraction experiments are within reach
[yes, I know ballistic doesn't mean phase-coherent, phase-coherent
includes low-scattering angle events, but it shows it isn't
impossible]