Decoherence of Impurities in a Fermi Sea of Ultracold Atoms

Cetina, Marko; Jag, Michael; Lous, Rianne S.; Walraven, J.T.M.; Grimm, Rudolf; Christensen, Rasmus S.; Bruun, Georg M.

doi:10.1103/physrevlett.115.135302

Cited by 125 publications

(187 citation statements)

References 33 publications

Supporting

Mentioning

177

Contrasting

Order By: Relevance

“…Firstly, the difference in polarizability of state |a and |m leads to a differential shift δ CM Lattice ∝ 2α ( 1 S0) − α m I Lattice as the external potentials experienced by the CM differ, where α ( 1 S0) is the polarizability of a ground-state atom and α m the polarizability of a molecule in state |m . Since the polarizability of weakly-bound molecules for far detuned light is close to the sum of the atomic polarizabilities of the constituent atoms we expect this shift to be small [35,36]. Secondly, the external confinement induces a differential shift on the eigenenergies of the relative motion Hamiltonian, leading to δ rel Lattice .…”

Section: Light Shifts From Lattice Lightmentioning

confidence: 99%

Efficient production of long-lived ultracold Sr2 molecules

et al. 2017

View full text Add to dashboard Cite

We associate Sr atom pairs on sites of a Mott insulator optically and coherently into weaklybound ground-state molecules, achieving an efficiency above 80%. This efficiency is 2.5 times higher than in our previous work [S. Stellmer, B. Pasquiou, R. Grimm, and F. Schreck, Phys. Rev. Lett. 109, 115302 (2012)] and obtained through two improvements. First, the lifetime of the molecules is increased beyond one minute by using an optical lattice wavelength that is further detuned from molecular transitions. Second, we compensate undesired dynamic light shifts that occur during the stimulated Raman adiabatic passage (STIRAP) used for molecule association. We also characterize and model STIRAP, providing insights into its limitations. Our work shows that significant molecule association efficiencies can be achieved even for atomic species or mixtures that lack Feshbach resonances suitable for magnetoassociation.

show abstract

Section: Light Shifts From Lattice Lightmentioning

confidence: 99%

Efficient production of long-lived ultracold Sr2 molecules

et al. 2017

View full text Add to dashboard Cite

show abstract

“…In this case, the bosons can be considered as impurities in the large Fermi sea. We now turn our attention to the specific situation of bosonic 41 K atoms in a Fermi sea of 6 Li atoms. The mixture [20,21] exhibits favorable properties for our purpose.…”

Section: A Basic Ideamentioning

confidence: 99%

“…Here, we first discuss the basic idea of our thermometry approach in general terms, before we turn our attention to the specific case of 41 K bosons in a 6 Li Fermi sea.…”

Section: Bosons As a Fermi Gas Thermometermentioning

confidence: 99%

“…For such a system, temperatures around 10% of the Fermi temperature T F or even below have been reported by various groups (see [9][10][11][12][13] for a few recent examples). Our thermometer is a small sample of bosonic 41 K atoms immersed in the Fermi sea. In addition to the condensate formation serving as the main observable, our system takes advantage of the large mass ratio and the much smaller number of bosons as compared to the fermions.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Thermometry of a deeply degenerate Fermi gas with a Bose-Einstein condensate

et al. 2017

Self Cite

View full text Add to dashboard Cite

We measure the temperature of a deeply degenerate Fermi gas, by using a weakly interacting sample of heavier bosonic atoms as a probe. This thermometry method relies on the thermalization between the two species and on the determination of the condensate fraction of the bosons. In our experimental implementation, a small sample of 41 K atoms serves as the thermometer for a 6 Li Fermi sea. We investigate the evaporative cooling of a 6 Li spin mixture in a single-beam optical dipole trap and observe how the condensate fraction of the thermometry atoms depends on the final trap depth. From the condensate fraction, the temperature can be readily extracted. We show that the lowest temperature of 5.9(5)% of the Fermi temperature is obtained, when the decreasing trap depth closely approaches the Fermi energy. To understand the systematic effects that may influence the results, we carefully investigate the role of the number of bosons and the thermalization dynamics between the two species. Our thermometry approach provides a conceptually simple, accurate, and general way to measure the temperature of deeply degenerate Fermi gases. Since the method is independent of the specific interaction conditions within the Fermi gas, it applies to both weakly and strongly interacting Fermi gases.

show abstract

“…Assuming the molecular and atomic magnetic moments differ μ m ≠ 2μ a , the vector light shift can bring the molecular states closer to the scattering state, inducing a resonant atom-molecule coupling. Optical shifts of a magnetic Feshbach resonance have been observed using specific bound-to-bound transitions [25][26][27][28] and recently using a far-detuned laser [38]. Since our scheme does not rely on proximity to any atomic or molecular transitions, the lifetime is only limited by the one-body off-resonant scattering rate.…”

mentioning

confidence: 94%

Casting New Light on Atomic Interactions

Vale

2015

Physics

View full text Add to dashboard Cite

Optical control of atomic interactions in quantum gases is a long-sought goal of cold atom research. Previous experiments have been hindered by rapid decay of the quantum gas and parasitic deformation of the trap potential. We develop and implement a generic scheme for optical control of Feshbach resonances which yields long quantum gas lifetimes and a negligible parasitic dipole force. We show that fast and local control of interactions leads to intriguing quantum dynamics in new regimes, highlighted by the formation of van der Waals molecules and localized collapse of a Bose condensate. DOI: 10.1103/PhysRevLett.115.155301 PACS numbers: 67.85.-d, 03.75.Kk, 34.50.-s Spatiotemporal control of interactions should bring a plethora of new quantum-mechanical phenomena into the realm of ultracold atom research. Temporal modulation of interactions is theoretically proposed as a route for creating anyonic statistics in optical lattices [1,2] as well as new types of quantum liquids [3,4] and excitations [5][6][7]. Spatial modulation should grant access to unusual soliton behavior [8,9], controlled interfaces between quantum phases [10], stable nonlinear Bloch oscillations [11], and even the dynamics of acoustic black holes [12]. The conventional technique for controlling interactions in cold atoms, magnetic Feshbach resonance [13,14], is typically insufficient for these applications because magnetic coils are generally too large for very fast or local modulation.A promising alternative is optical control of Feshbach resonances (OFR), with which high speed, spatially resolved control of interactions can be realized. Efforts toward achieving OFR in quantum gases have made significant progress [15-28] but have encountered two major obstacles. First, in previous experiments OFR has limited the quantum gas lifetime to the millisecond time scale [24,26,27] due to optical excitation to molecular states. Short lifetimes forbid studies of quantum gases in equilibrium or after typical dynamical time scales. Second, the change of interaction strength from OFR is often accompanied by an optical potential. This potential can result in a parasitic dipole force which dominates the dynamics when the interactions are spatially modulated [21].In this Letter we propose and implement a scheme for optically controlling interactions while maintaining a long quantum gas lifetime and negligible parasitic dipole force. With a far-detuned laser, a change of the scattering length a, which determines the interaction strength, by 180 Bohr radii (a 0 ) is only coupled with a slow radiative loss of 1.6 s −1 . This loss rate is sufficiently low to allow the BEC to remain in equilibrium. Furthermore, the laser operates at a magic wavelength to eliminate the atomic dipole potential. We apply OFR to test the response of Bose-Einstein condensates (BECs) to rapid oscillation of interactions down to the time scale of 10 ns, reaching beyond the van der Waals energy scale. Moreover, by spatially modulating the interaction strength we observe the intriguing...

show abstract

Decoherence of Impurities in a Fermi Sea of Ultracold Atoms

Cited by 125 publications

References 33 publications

Efficient production of long-lived ultracold Sr2 molecules

Efficient production of long-lived ultracold Sr2 molecules

Thermometry of a deeply degenerate Fermi gas with a Bose-Einstein condensate

Casting New Light on Atomic Interactions

Contact Info

Product

Resources

About