Ultracold Experiment Could Solve One of Physics's Biggest Contradictions — NOVA Next | PBS
'There’s a mysterious threshold that’s predicted to exist beyond the limits of what we can see. It’s called the quantum-classical transition.
If scientists were to find it, they’d be able to solve one of the most baffling questions in physics: why is it that a soccer ball or a ballet dancer both obey the Newtonian laws while the subatomic particles they’re made of behave according to quantum rules? Finding the bridge between the two could usher in a new era in physics.
We don’t yet know how the transition from the quantum world to the classical one occurs, but a new experiment, detailed in Physical Review Letters, might give us the opportunity to learn more.'http://www.pbs.org/wgbh/nova/next/physics/ultracold-experiment-could-solve-one-of-physicss-biggest-contradictions/Phys. Rev. Lett. 114, 143004 (2015) - Matter Wave Lensing to Picokelvin Temperatures
Using a matter wave lens and a long time of flight, we cool an ensemble of Rb87 atoms in two dimensions to an effective temperature of less than 50+50−30 pK. A short pulse of red-detuned light generates an optical dipole force that collimates the ensemble. We also report a three-dimensional magnetic lens that substantially reduces the chemical potential of evaporatively cooled ensembles with a high atom number. By observing such low temperatures, we set limits on proposed modifications to quantum mechanics in the macroscopic regime. These cooling techniques yield bright, collimated sources for precision atom interferometry.'http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.114.143004