Spontaneous topological defects in the formation of a Bose-Einstein condensate Matthew Davis 1 , Ashton Bradley 1,∗ , Geoff Lee 1 , Brian Anderson 2 1 ARC Centre of Excellence for Quantum-Atom Optics, University of Queensland, Brisbane, Australia. 2 College of Optical Sciences, University of Arizona, Tuscon, USA. * Now at Jack-Dodd Centre for Quantum Technology, University of Otago, Dunedin, New Zealand. Funding: Australian Research Council, National Science Foundation, University of Queensland. . – p.1
22
Embed
Spontaneous topological defects in the formation of …€¦ · Spontaneous topological defects in the formation of a Bose ... Stochastic Gross-Pitaevskii equation ... condensate
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Spontaneous topological defects in theformation of a Bose-Einstein condensate
Matthew Davis1, Ashton Bradley1,∗, Geoff Lee1, Brian Anderson2
1ARC Centre of Excellence for Quantum-Atom Optics, University of Queensland, Brisbane, Australia.2College of Optical Sciences, University of Arizona, Tuscon, USA.
∗Now at Jack-Dodd Centre for Quantum Technology, University of Otago, Dunedin, New Zealand.
Funding: Australian Research Council, National Science Foundation, University of Queensland.. – p.1
UQ theory 2 talks:Andrew Sykes: Force on a slow moving impurity due to quantum fluctuations in a 1D BEC (Wed 1250).
Joel Corney: Quantum dynamics of ultracold Fermions (Thu 830).
Ashton Bradley∗: Scale invariant thermodynamics of a toroidally Bose gas (Fri 1720).
Simon Haine: Generating number squeezing in a BEC through nonlinear interaction (Fri 1740).
UQ theory 2 posters:Andy Ferris: Detection of continuous variable entanglement without a coherent local oscillator
Geoff Lee: Coherence properties of a continuous-wave atom laser at finite temperature
Sarah Midgley: A comparative study of simulation methods for the dissociation of molecular BECs
Tania Haigh: Macroscopic superpositions in small double well condensates
Jacopo Sabbatini: Topological defect formation in 87Rb Bose Ferromagnet with quantum noise
Michael Garrett: Bose-Einstein Condensation in a Dimple Trap
Chao Feng: Mean-field study of superfluid critical velocity in a trapped Bose-Einstein condensate
UQ experiment:Erik van Ooijen: Macroscopic superpositions in small double well condensates
Leif Humbert: Towards an all-optical BEC in optical toroidal traps
Sebastian Schnelle: Ultra-cold atoms in a time averaged optical potential
. – p.2
Overview
1. Bose-Einstein condensation “phase transition” in a trap.
2. Finite temperature Bose gases.
3. Simulating condensate formation.
4. Observations of spontaneous vortices in BEC.
5. What causes spontaneous vortices in BEC?
6. Condensate formation in flat / elongated systems.
. – p.3
What is a Bose-Einstein condensate (BEC)?
It is a mesoscopic quantum many-body system:
• Typically 105 – 107 atoms in single translational quantum state.
• Matter equivalent of a single mode laser.
• Confined by lasers / magnetic fields in a vacuum.
• 100,000 times less dense than atmosphere.
• Form at temperatures around 100 nK.
• Size ≈ 100 µm.
To a good approximation:
• All atoms in a BEC share the same wave function.
How does it arise from a boring old incoherent thermal gas?. – p.4
The BEC phase transition
. – p.5
The BEC phase transition
0 0.2 0.4 0.6 0.8 1 1.2
0
0.2
0.4
0.6
0.8
1
1.2
T / Tc
N0 /
N
. – p.6
Non-equilibrium finite temperature BEC
Challenge: is it possible to develop a practical non-equilibriumformalism for finite temperature Bose gases?
Desirable features:
• Can deal with inhomogeneous potentials.
• Can treat interactions non-perturbatively.
• Calculations can be performed on a reasonable time scale (sayunder one week).