Ultracold gases Jami Kinnunen & Jani-Petri Martikainen Masterclass 2016

Radiation pressure: photon has wavevector q

Zeeman slower  Change the resonance frequency along the way as atoms are cooled by radiation pressure…

Zeeman slower William Phillips

Finnish connection in the early years

Laser cooling: below Doppler limit??

Sisuphys cooling  Two linearly polarized laser beams with orthogonal polarizations interfere  polarization varies in space

Sisuphys cooling This could 400 nK + prefactor

Sisuphys cooling

Quantum statistics

Boltzmann, Bose-Einstein, Fermi-Dirac

Interesting points  BE gives higher occupations for small energies  FD gives lower occupations for small energies (n=1 upper limit)  Derivation is kind of cleaner and more elegant for bosons and fermions…classical result is more of a mess.

Gross-Pitaevskii etc.

What to condense?

Bose-Einstein condensate: wavefunction?  What is it???

Interactions: scattering length  Contact interaction…  Billiard ball with radius “a”  That is a lie: complications exist

Dilute/weak interactions  What does it mean?  Gas of billiard balls at density n is dilute if…?  Check this for  ultracold cloud of Rb atoms  Liquid helium

Gross-Pitaevskii equation  Pure BEC governed by… This works very well in many realistic settings. Generalizations exist

Solid body rotation Impossible with a wavefunction?

Vortex: phase of the wavefunction

Vortex: higher “winding number”

How to get something like a classical solid body rotation?

Ongoing now: samples

Ultracold fermions Image: Moritz group,Hamburg Harder or easier than bosons?

Optical lattices

Slow light/light stopping 6sU

Can you swim in a superfluid

Swimming in a superfluid

Multicomponent swimmer

Quantum gas microscopes

Multicomponent systems  What are those?

Strongly interacting systems: beyond mean-field  Bye bye Gross-Pitaevskii  Weak to strong coupling transitions  Effective spin model

Throw the BEC from 146m tower  Because…why not!

Precision measurements  Clocks  Gravity  Acceleration

Long range interactions  Beyond billiard balls  Erbium magnetic dipole moment of 7 μB

Quantum information  Maybe a platform for some QI approaches?  Easy to get carried away with this though…buzzword