As cold as it gets

The atom trapping apparatus used to observe the physics described in the article. Credit: Washington State University

Scientists have been able to freeze a million atoms of rubidium at at temperature of a  100 billionth degrees above absolute zero in an experiment carried out at Washington State University. That is the coldest place in the whole universe (assuming there is not another lab somewhere with crazy scientists doing this kind of experiment).

At this temperature atoms stand still (almost) an enter into a state theoretically studied by Einstein and Bose (the Einstein Bose condensate) through a phase transition (the same phenomenon that happens when a solid transform into a liquid or a liquid into a gas or viceversa).

Phase transitions in physics are really interested since they change the behaviour characteristics of the set of atoms, e.g. a set of atoms in a gaseous state is compressible but after a phase transition into liquid becomes incompressible...

In this case the phase transition at this quasi 0 temperature transform the set of atoms in a coherent ensemble where each of the one million atoms is in synch with all the others and the million of them act as if it where just one. This characteristics was predicted by Robert Dyke in 1954 working at Princeton. He called this a super radiant characteristics.

Quantum effects that appears at the single atom level are now in effect in a million atoms, they are expanded and it gets easier to exploit them!  The million atoms occupy a space of about half a mm, tiny but visible at the naked eye: imagine you can see quantum effects in motion with just your eyes...  Well actually it is a bit more complicated but it gives the idea of the amazing feat achieved.

In this state the atoms show the same photon duality, particle and wave. This duality also means that an electron can be both in a spin up and down at the same time, or can be associated to 0 and 1 value at the same time. Welcome to the realm of quantum computer.

The experiment shows that we can have a quantum computer using million of atoms, rather than a single atom, and this makes its construction much easier.

Author - Roberto Saracco

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