BEC in microgravity W. Herr, Institute for Quantum Optics, Leibniz University of Hanover
Outline Reminder: Why microgravity? Why BEC? BEC in microgravity: Pilot project, Quantus Results Ongoing activity Future prospects Further leaps towards space Quantus2 Texus Seite 2
Reminder: Why microgravity? Extended time of evolution Sensitivity: Δϕ Δϕ rot acc 2 = r h r = k a T m Atom 2 r r A Ω T 2 r Ω r a T Sagnac Interferometer Seite 3
Reminder: Why BEC? Slower free expansion compared to ultra-cold thermal atoms Slowing the free expansion by lowering the trap depth before release of the condensate Less interaction and potential energy converted into kinetic energy BEC BEC Seite 4
BEC in microgravity: Pilot project Quantus Seite 5
Results: Evolution of the wave function Time-of-flight: 50, 100, 500 and 1000 ms ω x /2π 4Hz, ω y /2π 13Hz, ω Z /2π 22Hz 1400 μm 10 000 atoms T < 20nK delocalised after 1s over 1400 μm Seite 6
Results: Comparison with theoretical model 0.55 10-2 G/cm 2 1.32 10-2 G/cm 2 In-situ magnetometer for ultra-week magnetic field inhomogenities Seite 7
Ongoing activity: Preparation of F=2, m F =0 Adiabatic rapid passage Energy of the coupled system Radiofrequenz in MHz 0.8 0.6 0.4 0.2 0-0.2-0.4-0.6 m F =1 m F =0 m F =-1 m F =2 m F =-2-0.8 20.6 20.7 20.8 20.9 21 21.1 21.2 21.3 21.4 Energieaufspaltung Radiofrequency in MHz Seite 8
Ongoing activity: Bragg atom interferometry hω h( ω + δ ) e> time Energy hδ hω g> h( ω + δ ) hδ 0 1 2 Momentum in hk Seite 9
Summary of results and ongoing activity Results 170 drops Studied the evolution of the outcoupled condensate up to 1s Control of the condensate Detection of the residual magnetic fields with m F =2 Onoing activity Preparation of F=2, m F =0 Bragg Interferometry Testing the coherence Seite 10
Future prospects: Quantum reflection U U van-der-waals U Casimir-Polder ~x -3 ~x -4 0 v x Non-classical turning point Seite 11
Future prospects: Quantum reflection The MIT experiment: Saturated at R max = 60% Low velocity quantum reflection of Bose-Einstein condensates T. A. Pasquini et al. PRL 97 (2006) Seite 12
Future prospects: Quantum reflection The theory: 0 v s = l l v s // v h² n0a / πm² peak density of the BEC Anomalous Quantum Reflection of Bose-Einstein condensates from a Silicon Surface. The role of dynamical excitations R. G. Scott, et al. PRL 95 (2005) Seite 13
Future prospects: Quantum reflection Comparison: MIT: n0 10 mm v s 0. 28 s 12 = 2.2 cm 3 Quantus: n0 1 10 3 v s 10 cm mm s 7 3 R 100% Seite 14
Future prospects: more Anderson localisation Anderson, Phys. Rev. 109, 1492 1505 (1958), Billy et al., Nature 453, 891-894 (2008), Giacomo Roati et al., Nature 453, 895 898 (2008). Atomic chip clocks Treutlein et al. PRL 92, 203005 (2004) Artificial Electromagnetism Ruseckas et al., PRA 71 053614 (2005) Non-abelian atom optics Gediminas Juzeliunas et al., PRL 100, 200405 (2008) Seite 15
Further leaps towards space: Quantus2 Reduce size of the apparatus to approx. half (to ca. 1m³) Double time of microgravity to 9s by using the catapult mode Add second atomic species: Potassium (fermionic 40 K) Add 2D-MOT for faster loading rates and better vacuum quality Optimise performance of the atom chip for use in microgravity Feasibility for precision Raman spectroscopy Test of the weak equivalence principle (part of ) Seite 16
Further leaps towards space: Texus Ballistic missile launch Quality of microgravity 10-5 (ZARM 10-6 ) 6 minutes of microgravity (ZARM 9s) Seite 17
Thank you for your attention Quantus is a collaboration of Financed by: Seite 18