Wide Awake Developers

Quantum Manipulations

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I work in information technology, but my first love is science.  Particularly the hard sciences of physics and cosmology.

There’ve been a series of experiments over the last few years that have demonstrated quantum manipulations of light and matter that approach the macroscopic realm.

A recent result from Harvard (HT to Dion Stewart for the link) has gotten a lot of (incorrect) play.  It involves absorbing photons with a Bose-Einstein condensate, then reproducing identical photons at some distance in time and space.  I’ve been reading about these experiments with a lot of interest, along with the experiments going the "other" direction: supraluminal group phase travel.

I wish the science writers would find a new metaphor, though.  They all talk in terms of "stopping light" or "speeding up light".  None of these have to do with changing the speed of light, either up or down.  This is about photons, not the speed of light.

In fact, this latest one is even more interesting when you view it in terms of the "computational universe" theory of Seth Lloyd.  What they’ve done is captured the complete quantum state of the photons, somehow ‘imprinted’ on the atoms in the condensate, then recreated the photons from that quantum state.

This isn’t mere matter-energy conversion as the headlines have said.  It’s something much more.

The Bose-Einstein condensate can be described as a phase of matter colder than a solid.  It’s much weirder than that, though.  In the condensate, all the particles in all the atoms achieve a single wavefunction.  You can describe the entire collection of protons, neutrons and electrons as if it were one big particle with its own wavefunction.

This experiment with the photons shows that the photons’ wavefunctions can be superposed with the wavefunction of the condesnate, then later extracted to separate the photons from the condensate.

The articles somewhat misrepresent this as being about converting light (energy) to matter, but its really about converting the photon particles to pure information then using that information to recreate identical particles elsewhere.  Yikes!