The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang
description
Transcript of The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang
![Page 1: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/1.jpg)
Stability of a Fermi Gas
with Three Spin StatesThe Pennsylvania State University
Ken O’Hara
Jason Williams
Eric Hazlett
Ronald Stites
Yi Zhang
John Huckans
![Page 2: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/2.jpg)
Three-Component Fermi Gases
• Many-body physics in a 3-State Fermi Gas– Mechanical stability with resonant interactions an open question
– Novel many-body phasesCompetition between different Cooper pairs
Competition between Cooper pairing and 3-body bound states
Analog to Color Superconductivity and Baryon Formation in QCD
Polarized 3-state Fermi gases: Imbalanced Fermi surfacesNovel Cooper pairing mechanismsAnalogous to mass imbalance of quarks
![Page 3: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/3.jpg)
QCD Phase Diagram
C. Sa de Melo, Physics Today, Oct. 2008
![Page 4: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/4.jpg)
Simulating the QCD Phase Diagram
Rapp, Hofstetter & Zaránd,
PRB 77, 144520 (2008)
• Color Superconducting-to-“Baryon” Phase Transition
• 3-state Fermi gas in an optical lattice– Rapp, Honerkamp, Zaránd & Hofstetter,
PRL 98, 160405 (2007)
• A Color Superconductor in a 1D Harmonic Trap– Liu, Hu, & Drummond, PRA 77, 013622 (2008)
![Page 5: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/5.jpg)
Universal Three-Body Physics
• The Efimov Effect in a Fermi system– Three independent scattering lengths– More complex than Efimov’s original scenario– New phenomena (e.g. exchange reactions)
• Importance to many-body phenomena– Two-body and three-body physics completely
described– Three-body recombination rate determines
stability of the gas
![Page 6: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/6.jpg)
Three-State 6Li Fermi Gas
2/3F
2/1F
}
}1
2
3
Hyperfine States of 6Li
2/1sm
2/1sm
![Page 7: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/7.jpg)
• No Spin-Exchange Collisions– Energetically forbidden
(in a bias field)
• Minimal Dipolar Relaxation– Suppressed at high B-field
• Electron spin-flip process irrelevant in electron-spin-polarized gas
• Three-Body Recombination– Allowed in a 3-state mixture– (Exclusion principle suppression for 2-state mixture)
2/3F
2/1F
}
}1
2
3
Inelastic Collisions
![Page 8: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/8.jpg)
Making and Probing 3-State Mixtures
Magnetic Field (Gauss)
200 400 600 800 10000
Radio-frequency magnetic fields drive transitions
Spectroscopically resolved absorption imaging
![Page 9: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/9.jpg)
The Resonant QM 3-Body Problem
Vitaly Efimov circa 1970
(1970) Efimov: An infinite number of bound 3-body states for
A single 3-body parameter:
Inner wall B.C.determined byshort-range interactions
Infinitely many 3-body bound states (universal scaling):
)0(TE
)2(TE
)1(TE
· · )(TE
a
. ·
![Page 10: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/10.jpg)
QM 3-Body Problem for Large a(1970 & 1971) Efimov: Identical Bosons in Universal Regime
Note: Only two free parameters:
Log-periodic scaling:
E. Braaten, et al. PRL 103, 073202
7.22)(*
)1(* nn aa
0a0a &Diagram from: E. Braaten & H.-W. Hammer, Ann. Phys. 322, 120 (2007)
Observable for a < 0: Enhanced 3-body recombination rate at
![Page 11: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/11.jpg)
Universal Regions in 6Li
![Page 12: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/12.jpg)
The Threshold Regime and the Unitarity Limit
• Universal predictions only valid at threshold– Collision Energy must be small
• Smallest characteristic energy scale
• Comparison to theory requires low temperature
• and low density (for fermions)
• Recombination rate unitarity limited in a thermal gas
![Page 13: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/13.jpg)
Making Fermi Gases Cold
• Evaporative Cooling in an Optical Trap
• Optical Trap Formed from two 1064 nm, 80 Watt laser beams
• Create incoherent 3-state mixture– Optical pumping into F=1/2 ground state– Apply two RF fields in presence of field gradient
![Page 14: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/14.jpg)
Making Fermi Gases UltracoldAdiabatically Release Gas into a Larger Volume Trap
![Page 15: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/15.jpg)
Low Field Loss Features
Resonances in the 3-Body Recombination Rate!
Resonance Resonance
T. B. Ottenstein et al., PRL 101, 203202 (2008). J. H. Huckans et al., PRL102, 165302 (2009).
![Page 16: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/16.jpg)
Measuring 3-Body Rate Constants
Loss of atoms due to recombination:
Evolution assuming a thermal
gas at temperature T :
“Anti-evaporation” and
recombination heating:
![Page 17: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/17.jpg)
Recombination Rate in Low-Field Region
![Page 18: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/18.jpg)
Recombination Rate in Low-Field Region
P. Naidon and M. Ueda, PRL 103, 073203 (2008).
E. Braaten et al., PRL 103, 073202 (2009).
S. Floerchinger, R. Schmidt, and C. Wetterich, Phys. Rev. A 79, 053633 (2009)
![Page 19: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/19.jpg)
Recombination Rate in Low-Field Region
P. Naidon and M. Ueda, PRL 103, 073203 (2008).
E. Braaten et al., PRL 103, 073202 (2009).
S. Floerchinger, R. Schmidt, and C. Wetterich, Phys. Rev. A 79, 053633 (2009)
Better agreement if h* tunes with magnetic field – A. Wenz et al., arXiv:0906.4378 (2009).
![Page 20: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/20.jpg)
Efimov Trimer in Low-Field Region
![Page 21: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/21.jpg)
3-Body Recombination in High Field Region
![Page 22: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/22.jpg)
3-Body Recombination in High Field Region
![Page 23: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/23.jpg)
Determining the Efimov Parameters
using calculations from E. Braaten et al., PRL 103, 073202 (2009).
![Page 24: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/24.jpg)
Determining the Efimov Parameters
using calculations from E. Braaten et al., PRL 103, 073202 (2009).
![Page 25: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/25.jpg)
Determining the Efimov Parameters
using calculations from E. Braaten et al., PRL 103, 073202 (2009).
![Page 26: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/26.jpg)
Efimov Trimers in High-Field Region
also predicts 3-body loss resonances at 125(3) and 499(2) G
![Page 27: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/27.jpg)
3-Body Observables in High Field Region
from E. Braaten, H.-W. Hammer, D. Kang and L. Platter, arXiv (2009).
![Page 28: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/28.jpg)
Prospects for Color Superfluidity
• Color Superfluidity in a Lattice (increased density of states)– TC = 0.2 TF (in a lattice with d = 2 mm, V0 = 3 ER )
– Atom density ~1011 /cc– Atom lifetime ~ 200 ms (K3 ~ 5 x 10-22 cm6/s)
– Timescale for Cooper pair formation
![Page 29: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/29.jpg)
Summary• Observed variation of three-body recombination rate by 8 orders of
magnitude
• Experimental evidence for ground and excited state Efimov trimers in a three-component Fermi gas
• Observation of Efimov resonance near three overlapping Feshbach resonances
• Determined three-body parameters in the high field regime which is well described by universality
• The value of k* is nearly identical for the high-field and low-field
regions despite crossing non-universal region
• Three-body recombination rate is large but does not necessarily prohibit future studies of many-body physics
![Page 30: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/30.jpg)
Fermi Gas Group at Penn State
Ken O’Hara John Huckans Ron Stites Eric Hazlett Jason Williams Yi Zhang
![Page 31: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/31.jpg)
Future Prospects
• Efimov Physics in Ultracold Atoms– Direct observation of Efimov Trimers– Efimov Physics (or lack thereof) in lower dimensions
• Many-body phenomena with 3-Component Fermi Gases
![Page 32: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/32.jpg)
![Page 33: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/33.jpg)
![Page 34: The Pennsylvania State University Ken O’Hara Jason Williams Eric Hazlett Ronald Stites Yi Zhang](https://reader036.fdocuments.in/reader036/viewer/2022062321/56813ba6550346895da4d70f/html5/thumbnails/34.jpg)