Go Back   Science Forums Biology Forum Molecular Biology Forum Physics Chemistry Forum > General Science Forums > Physics Forum
Register Search Today's Posts Mark Forums Read

Physics Forum Physics Forum. Discuss and ask physics questions, kinematics and other physics problems.


Decoherence is caused by the thermal emission of photons from the molecules

Decoherence is caused by the thermal emission of photons from the molecules - Physics Forum

Decoherence is caused by the thermal emission of photons from the molecules - Physics Forum. Discuss and ask physics questions, kinematics and other physics problems.


Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 02-19-2004, 01:35 PM
Bubba Do Wah Ditty
Guest
 
Posts: n/a
Default Decoherence is caused by the thermal emission of photons from the molecules



Looking at decoherence
18 February 2004

Physicists in Austria have observed decoherence - the transition from
quantum to classical behaviour - in carbon-70 molecules. At temperatures
below 1000 Kelvin the molecules demonstrate quantum behaviour when they pass
through a double slit. However, the molecules gradually become classical at
higher temperatures, and the interference pattern - which is the classic
sign of quantum behaviour - becomes weaker. Markus Arndt, Anton Zeilinger
and co-workers at the University of Vienna in Austria have shown that the
decoherence is caused by the thermal emission of photons from the molecules
(L Hackermüller et al. 2004 Nature 427 711)

Researchers have seen quantum interference effects in electrons, atoms and
small molecules but never in macroscopic objects. In 1999, the Vienna group
observed wave properties in carbon-60 and carbon-70 molecules. With a
diameter of about 1 nanometre, these were the biggest objects to have shown
quantum interference at the time. Since then, the team has observed wave
properties in larger molecules such as tetraphenylporphyrin. This molecule,
which is present in chlorophyll and haemoglobin, has a diameter of about 2
nanometres.

Arndt and co-workers first sent a beam of carbon-70 molecules through a
laser system that heated them to around 5000 Kelvin. As the molecules then
cooled down by emitting photons, they were passed through an interferometer
that contained three sets of diffraction gratings. The first grating
produced a coherent beam of molecules, the second created the interference
pattern, and the third imaged this pattern. The slits in the gratings were
about 500 nanometres wide and the grating had a period of around 1000
nanometres.

The Vienna physicists found that below about 1000 Kelvin, a high-quality
interference fringe pattern characteristic of quantum behaviour could be
seen. However, these patterns gradually vanished as the molecules were
heated and started to emit thermal radiation. Since these photons could, in
principle, be detected to reveal which slit the molecule has passed through,
the wave-like quantum behaviour of the molecules disappears. The group now
hopes to observe the effect of decoherence in even larger molecules, such as
proteins.

Author
Belle Dumé is Science Writer at PhysicsWeb
--
Bubba Do Wah Ditty

"Rarely is the question asked: Is our children learning?"

- Bushisms, 2000




Reply With Quote
Reply

Tags
caused , decoherence , emission , molecules , photons , thermal


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Moving Dimensions Theory Book Due Out in Fall 05--Very Rough Draft: 4th Dimensions Expanding Relative to 3 Spatial Dimensions jollyrogership@yahoo.com Physics Forum 64 03-31-2012 10:24 AM
Simply put, MOVING DIMENSIONS THEORY is THE NEW MODEL: http://physicsmathforums.com drelliot@gmail.com Physics Forum 0 08-29-2006 06:32 AM
Moving Dimensions Theory!! Rock On!! drelliot@gmail.com Physics Forum 1 07-06-2006 05:19 PM
The Theory of Moving Dimensions: The Time Dimension is Moving Relative to The Three Spatial Dimensions Captain Ranger McCoy Physics Forum 14 07-03-2005 03:14 AM


All times are GMT. The time now is 02:02 AM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright 2005 - 2012 Molecular Station | All Rights Reserved
Page generated in 0.15771 seconds with 16 queries