Scientists manage to study the physics that connect the classical the quantum world

Sep 09, 2013
Principle of the experiment: In the beginning the atom cloud is prepared in an almost perfectly ordered quantum state (symbolized by gray atoms). Over time, this quantum order is lost and disorder spreads through the system with a certain well-defined velocity (symbolized by the mixture of red and gray atoms). This disorder can be associated with the emergence of a temperature. The initial quantum properties are lost only through interactions between the atoms, without any influence from the outside world.

How does a classical temperature form in the quantum world? An experiment at the Vienna University of Technology has directly observed the emergence and the spreading of a temperature in a quantum system. Remarkably, the quantum properties are lost, even though the quantum system is completely isolated and not connected to the outside world. The experimental results are being published in this week's issue of Nature Physics.

Quantum and classical physics: From the microscopic to the macroscopic world

The connection between the of and our everyday experience, which is concerned with much larger objects, still remains puzzling. When a quantum system is measured, it is inevitably disturbed and some of its are lost.

A cloud of atoms, for example, can be prepared in such away that each atom is simultaneously located at two different places, forming a perfect . As soon as the location of the atoms is measured, however, this superposition is destroyed. All that is left are atoms sitting at some well-defined places. They behave just as classical objects would.

In this case, the transition from to classical behavior is initiated by the measurement – a contact with the outside world. But what happens, if a is not influenced from the outside at all? Can classical properties still emerge?

Atom chip used to cool and manipulate the ultracold atomic clouds.

Disorder in the quantum world

"We are studying clouds consisting of several thousand atoms", explains Tim Langen, lead author of the study from Professor Jörg Schmiedmayer's research team at Vienna University of Technology. "Such a cloud is small enough to effectively isolate it from the rest of the world, but it is large enough to study how quantum properties are lost".

In the experiment, the atom clouds are split into two halves. After a certain time the two halves are compared to each other. In that way, the scientists can measure the amount of quantum mechanical connection between the clouds. Initially, this connection is perfect; all atoms are in a highly ordered quantum state. But as the cloud is a large object consisting of thousands of particles, this order does not remain for long.

Loss of quantum properties without influence from outside

As the atoms interact with each other, disorder begins to spread with a certain velocity. Atoms in the already disordered regions lose their quantum properties. A temperature can be assigned to them – just as in a classical gas. "The velocity with which the disorder spreads depends on the number of atoms", says Tim Langen. This defines a clear border between the regions which can be described by a classical temperature and regions where quantum properties remain unchanged.

After a certain time the disorder has spread over the whole cloud. The remarkable observation is that this loss of quantum properties happens just because of quantum effects inside the atom cloud, without any influence from the outside world. "So far, such a behavior had only been conjectured, but our experiments demonstrate that nature really behaves like this", Jörg Schmiedmayer points out.

Atomic clouds: A world on its own

In a way, the atomic cloud behaves like its own miniature universe. It is isolated from the environment, so its behavior is solely determined by its internal properties. Starting with a completely quantum mechanical state, the cloud looks "classical" after some time, even though it evolves according to the laws of quantum physics. That is why the experiment could not just help us to understand the behavior of large atom clouds, it could also help to explain, why the world that we experience every day looks so classical, even though it is governed by quantum laws.

Explore further: When parallel worlds collide, quantum mechanics is born

More information: www.nature.com/nphys/journal/v… /full/nphys2739.html

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vacuum-mechanics
1 / 5 (16) Sep 09, 2013
How does a classical temperature form in the quantum world? An experiment at the Vienna University of Technology has directly observed the emergence and the spreading of a temperature in a quantum system. Remarkably, the quantum properties are lost, even though the quantum system is completely isolated and not connected to the outside world. The experimental results are being published in this week's issue of Nature Physics.


The problem seems arisen because of our ignorance in quantum mechanics; maybe understand its working mechanism could help to explain what happen ….
http://www.vacuum...19〈=en

beleg
1 / 5 (2) Sep 09, 2013
No one told an isolated (insulated?)quantum order to get lost.
Fluctuation-ists did it.
hemitite
1 / 5 (1) Sep 09, 2013
Looks like entropy increasing to me.
Noumenon
1 / 5 (7) Sep 09, 2013
It just seems like quantum decoherence with the system being it's own environment.
clay_ferguson
2.1 / 5 (11) Sep 09, 2013
Anybody else bothered by the typo in the title? Shouldn't there be a "to" in there ?
clay_ferguson
1.9 / 5 (9) Sep 09, 2013
The problem seems arisen because of our ignorance in quantum mechanics; maybe understand its working mechanism could help to explain what happen ….
http://www.vacuum...19〈=en

@vaccum-head, you have been posting nonsense on this site for years, and none of it has ever made any sense to the ones of us who know some physics, and who find your delusions of grandeur at least amusing if not pathological.

Torbjorn_Larsson_OM
3 / 5 (2) Sep 09, 2013
It is also amusing that a d-o-g person* takes an experiment that disproves his claims as a cause of claiming the exact opposite. Who would even bother to follow a link from an obviously insane person?

* Q: If a delusion-of-grandeur person is a d-o-g person, what is a c-a-t person?
beleg
1 / 5 (3) Sep 10, 2013
Label entropy the artifact of this negative energy experiment.
And the objection to call entropy an artifact is one of resentment than reason.
MikeBowler
1 / 5 (1) Sep 10, 2013
they say that the systems changes are determined solely by its own internal properties, can things such as virtual particles not be factored into this?
MikeBowler
4 / 5 (4) Sep 10, 2013
... this study didn't observe nothing conceptually new ...--- Teech2

or put another way:
this study "did" observe "something" conceptually new
DonGateley
1 / 5 (2) Sep 10, 2013
Re isolation. I don't believe we have yet achieved a gravity shield. Could that be a player here? Just askin' ya unnerstan'.
Q-Star
5 / 5 (2) Sep 10, 2013
this study "did" observe "something" conceptually new
Now, what is it?


He's referring to your double negative. Ya said the exact opposite of what ya wanted to say.
DonGateley
3 / 5 (2) Sep 10, 2013
So Teech2 and Franklins really are the same sock puppets! Why the ruse?