Physicists Successfully Store and Retrieve Nothing

In summary, two teams have successfully stored and retrieved a "squeezed vacuum" state of light in a puff of gas, building on previous efforts to stop light in its tracks. This may lead to advancements in quantum information and telecommunication technologies. However, the concept of a "vacuum state" is not universal and can be affected by quantum mechanics, such as in the case of squeezed states. These squeezed states can also be related to canonical transformations in classical Hamiltonian dynamics. The squeezed vacuum is not actually a vacuum, as it contains a large but uncertain number of quanta and has a mean energy larger than the ground state energy. Finally, some may view this type of story as sensationalized and not truly representative of the experiment
  • #1
SF
By Adrian Cho
ScienceNOW Daily News
29 February 2008
It sounds like a headline from the spoof newspaper The Onion, but for physicists, this is actually an achievement: Two teams have stored nothing in a puff of gas and then retrieved it a split second later. Storing a strange form of vacuum builds on previous efforts in which researchers stopped light in its tracks (ScienceNOW, 22 January 2001) and may mark a significant step toward new quantum information and telecommunication technologies.

http://sciencenow.sciencemag.org/cgi/content/full/2008/229/1
 
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  • #2
SF said:
Two teams have stored nothing in a puff of gas and then retrieved it a split second later. Storing a strange form of vacuum builds on previous efforts in which researchers stopped light in its tracks (ScienceNOW, 22 January 2001) and may mark a significant step toward new quantum information and telecommunication technologies.

For the benefit of other readers, the article is about "storing" a "squeezed vacuum"
state of light.

The notion of "squeezed" states basically refers to the possibility that, given a minimum
uncertainty state, where [itex]\Delta p \Delta q =[/itex] (minimum), one can play with
the individual uncertainties in position and momentum (e.g: increasing [itex]\Delta p[/itex]
but decreasing [itex]\Delta q[/itex], while still maintaining the minimum uncertainty
product. It's called "squeezing" because if you draw a diagram of this in phase space,
a circle gets squeezed to an ellipse (while maintaining total area).

This idea applies to state of zero photons (normally called a "vacuum"). If a
"vacuum" state has (determinately) zero energy-momentum, it must have totally
indeterminate position. If confined in space (so that its position uncertainty
decreases, its momentum uncertainty must increase). The experiment just
confirms the well-known fact that the details of what's happing at the
so-called "dark" ports in a quantum optics experiment are important
quantum mechanically. There is not just a single unique universal notion of
"vacuum state" in general.

Wikipedia has more: http://en.wikipedia.org/wiki/Squeezed_state

The squeezing transformations correspond to certain "canonical transformations"
in classical Hamiltonian dynamics (which can mix position and momentum
variables without changing the form of Hamilton's equations). The full group of
these canonical transformations is not always well-represented when one passes
to a quantum theory. E.g., in (infinite-dimensional) QFT based on unitary irreps
of the Poincare group, one finds that there are physically-important
transformations (field displacements, Bogoliubov transformations) that are
useful in generalized coherent states, superconductivity, and more,
but are not implemented sensibly in the usual Hilbert-Fock space.
 
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  • #3
The squeezed vacuum is actually not a vacuum. It contains a large (but uncertain) number of quanta. Its mean energy is larger than the ground state energy. Hence it is not "nothing".
 
  • #4
yawn... this kind of story just makes physicists look like idiots, just like their earlier story on "stopping light". some droll sort of scientific sensationalism, which after written for the masses by some semi-scientist makes little sense and generally the story has next to nothing to do with the actual experiment or its results.
 

Related to Physicists Successfully Store and Retrieve Nothing

1. What does it mean to "store and retrieve nothing" in physics?

In this context, "nothing" refers to a quantum vacuum state, which is the lowest possible energy state of a quantum mechanical system. Physicists were able to manipulate and control this state, essentially storing and retrieving it for future use.

2. How is this accomplishment significant in the field of physics?

This achievement is significant because it demonstrates our growing understanding and ability to manipulate quantum states. It also has practical implications for quantum computing and communication.

3. How was this feat accomplished?

The physicists used a combination of lasers and magnetic fields to trap and manipulate a group of atoms, causing them to enter a quantum vacuum state. They were then able to retrieve the atoms from this state, essentially "storing and retrieving nothing."

4. What are the potential applications of this research?

Aside from advances in quantum computing and communication, this research could also have implications for precision measurements and quantum simulations. It may also lead to a better understanding of the fundamental nature of quantum mechanics.

5. What further research is needed in this area?

Further research is needed to better understand and control quantum vacuum states, as well as to explore potential applications and implications of this research. Additionally, more studies could be conducted to investigate the potential for creating and manipulating other quantum states.

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