Experiments and General Properties What is a Roton? Our Work Summary Dipolar Interactions and Rotons in Ultracold Atomic Quantum Gases Falk W¨ achtler Workshop of the RTG 1729 L¨ uneburg March 13., 2014 Falk W¨ achtler Dipolar Interactions and Rotons in Atomic Quantum Gases
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Experiments and General Properties What is a Roton? Our ... · Experiments and General Properties What is a Roton? Our Work Summary Realization of dipolar Systems Erbium Magnetic
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Experiments and General PropertiesWhat is a Roton?
Our WorkSummary
Dipolar Interactions and Rotons in Ultracold AtomicQuantum Gases
Falk Wachtler
Workshop of the RTG 1729Luneburg
March 13., 2014
Falk Wachtler Dipolar Interactions and Rotons in Atomic Quantum Gases
Experiments and General PropertiesWhat is a Roton?
Our WorkSummary
Realization of dipolar SystemsErbium
Table of contents
1 Experiments and General PropertiesRealization of dipolar SystemsErbium
2 What is a Roton?Excitation spectrumExcitation SpectraRoton Confinement
3 Our WorkProblem of validityCalculation Scheme
4 Summary
Falk Wachtler Dipolar Interactions and Rotons in Atomic Quantum Gases
Experiments and General PropertiesWhat is a Roton?
Our WorkSummary
Realization of dipolar SystemsErbium
Dipole-Dipole Interactions
Dipolar Interactions in magnetic and electric systems
long ranged and anisotropic
U =Cdd
4π
1− 3 cos2 θ
r3
magnetic:
CBdd = µ0m
2
permanent magnetic dipoles in atoms
electric:
CEdd = 4πd2
polar molecules, Rydberg atoms, andlight-induced dipoles in atoms
Falk Wachtler Dipolar Interactions and Rotons in Atomic Quantum Gases
Experiments and General PropertiesWhat is a Roton?
Our WorkSummary
Realization of dipolar SystemsErbium
Magnetic Systems
Realized samplesBoson: 52Cr A. Griesmaier, J. Werner, S. Hensler, J. Stuhler, and
T. Pfau, PRL 94, 160401 (2005)
Fermion: 53Cr R. Chicireanu, A. Pouderous, R. Barbe, B.
Laburthe-Tolra, E. Marechal, L. Vernac, J.-C. Keller, and O.
Gorceix, PRA 73, 053406 (2006)
Boson: 87Rb M. Vengalattore, S. R. Leslie, J. Guzman, and D. M.
Stamper-Kurn, PRL 100, 170403 (2008)
Boson: 164Dy M. Lu, N. Burdick, S. Youn, and B. Lev, PRL 107,
190401 (2011)
Boson: 168Er K. Aikawa, A. Frisch, M. Mark, S. Baier, A. Rietzler,
R. Grimm, and F. Ferlaino, PRL 108, 210401 (2012)
Fermion: 167Er Aikawa et al., arXiv:1310.5676 (2013)
Falk Wachtler Dipolar Interactions and Rotons in Atomic Quantum Gases
Experiments and General PropertiesWhat is a Roton?
Our WorkSummary
Realization of dipolar SystemsErbium
Erbium: Collisional properties
producing BEC and degenerate Fermi gases of Erbium
complicated collisional properties → lot of Feshbachresonances
lot of Feshbach resonances within small B-range → bettercontrol of contact strength
Falk Wachtler Dipolar Interactions and Rotons in Atomic Quantum Gases
Experiments and General PropertiesWhat is a Roton?
Our WorkSummary
Realization of dipolar SystemsErbium
Cooling of Fermions
No s-wave collisions in spin-polarized Fermi gases
Without dipole-dipole interaction no direct evaporative cooling
Strong dipole-dipole interactions lead to thermalizationthrough p-wave interactions
Very small inelastic collisions due to large p-wave barrier
K. Aikawa, A.Frisch, M. Mark, S.Baier, R. Grimm,and F. Ferlaino,arXiv:1310.5676(2013)
Falk Wachtler Dipolar Interactions and Rotons in Atomic Quantum Gases
Experiments and General PropertiesWhat is a Roton?
Our WorkSummary
Realization of dipolar SystemsErbium
Stability
Dipole-dipole interaction is partially attractive → stabilitydepends on contact interaction and geometry
T.Lahaye et al., Rep. Prog. Phys. 72, 126401 (2009)
Falk Wachtler Dipolar Interactions and Rotons in Atomic Quantum Gases
Experiments and General PropertiesWhat is a Roton?