Slashdot Mirror
'Zeno Effect' Verified: Atoms Won't Move While You Watch (cornell.edu)
An anonymous reader writes: One of the oddest predictions of quantum theory – that a system can't change while you're watching it – has been confirmed in an experiment by Cornell physicists. Graduate students Yogesh Patil and Srivatsan Chakram created and cooled a gas of about a billion Rubidium atoms inside a vacuum chamber and suspended the mass between laser beams (abstract).
In that state the atoms arrange in an orderly lattice just as they would in a crystalline solid. But at such low temperatures the atoms can "tunnel" from place to place in the lattice. The famous Heisenberg uncertainty principle says that position and velocity of a particle are related and cannot be simultaneously measured precisely.
The researchers observed the atoms under a microscope by illuminating them with a separate imaging laser. A light microscope can't see individual atoms, but the imaging laser causes them to fluoresce, and the microscope captured the flashes of light. When the imaging laser was off, or turned on only dimly, the atoms tunneled freely. But as the imaging beam was made brighter and measurements made more frequently, the tunneling reduced dramatically.
In that state the atoms arrange in an orderly lattice just as they would in a crystalline solid. But at such low temperatures the atoms can "tunnel" from place to place in the lattice. The famous Heisenberg uncertainty principle says that position and velocity of a particle are related and cannot be simultaneously measured precisely.
The researchers observed the atoms under a microscope by illuminating them with a separate imaging laser. A light microscope can't see individual atoms, but the imaging laser causes them to fluoresce, and the microscope captured the flashes of light. When the imaging laser was off, or turned on only dimly, the atoms tunneled freely. But as the imaging beam was made brighter and measurements made more frequently, the tunneling reduced dramatically.
Weeping Atoms dept
Is it the laser or is it the looking? Sounds to me like you found an effect triggered by the laser over a certain intensity, as, the way I read it, under that intensity everything works just great, even if you enter a staring contest.
Put another way, imagine the universe is a simulation. The programmer didn't want to waste CPU cycles simulating every single atomic particle, so when no meaningful atomic-scale interactions are occurring, the simulation uses a simpler statistical model instead.
When the laser light is striking the atoms in the lattice, the interactions between the light and lattice force the simulation to model every individual atom and photon. So each them are modeled precisely, and no tunneling occurs.
When the laser light is not striking the atoms in the lattice, there's no need to model every (non-)interaction and the simulation reverts to a statistical model. When the laser is turned on again you can locate the position of every atom again. Since the original lattice arrangement was not "saved", the simulation has to generate a new arrangement of atoms in the lattice. This new arrangement is statistically identical to the original, but little details like the positions of individual atoms are not identical. The misplaced atoms appear to have "moved", and we call those movements "tunneling".
Have fun sleeping tonight. -- The Matrix