arXiv subjects

C. Ticknor

Publications and source records attributed to C. Ticknor.

25 records · Page 2Linked to original sources

arXiv2008

Binding Energies of 6Li p-wave Feshbach Molecules

We present measurements of the binding energies of $^6$Li p-wave Feshbach molecules formed in combinations of the (F = 1/2, m_F = +1/2), (1), and (F = 1/2, m_F = -1/2), (2), states. The binding energies scale linearly with magnetic field detuning for all three resonances. The relative molecular magnetic moments are found to be $113 \pm 7 μ$K/G, $111 \pm 6 μ$K/G and $118 \pm 8 μ$K/G for the (1)-(1), (1)-(2) and (2)-(2) resonances, respectively, in good agreement with theoretical predictions. Closed channel amplitudes and the size of the p-wave molecules are obtained theoretically from full closed-coupled calculations.

cond-mat.other↗

arXiv2004

Observation of Heteronuclear Feshbach Resonances in a Bose-Fermi Mixture

Three magnetic-field induced heteronuclear Feshbach resonances were identified in collisions between bosonic 87Rb and fermionic 40K atoms in their absolute ground states. Strong inelastic loss from an optically trapped mixture was observed at the resonance positions of 492, 512, and 543 +/- 2 G. The magnetic-field locations of these resonances place a tight constraint on the triplet and singlet cross-species scattering lengths, yielding -281 +/- 15 Bohr and -54 +/- 12 Bohr, respectively. The width of the loss feature at 543 G is 3.7 +/- 1.5 G wide; this broad Feshbach resonance should enable experimental control of the interspecies interactions.

cond-mat.soft↗

arXiv2003

Multiplet Structure of Feshbach Resonances in non-zero partial waves

We report a unique feature of magnetic field Feshbach resonances in which atoms collide with non-zero orbital angular momentum. P-wave ($l=1$) Feshbach resonances are split into two components depending on the magnitude of the resonant state's projection of orbital angular momentum onto the field axis. This splitting is due to the magnetic dipole-dipole interaction between the atoms and it offers a means to tune anisotropic interactions of an ultra-cold gas of atoms. A parameterization of the resonance in terms of an effective range expansion is given.

physics.atom-ph↗

arXiv2003

Detection of spatial correlations in an ultracold gas of fermions

Spatial correlations are observed in an ultracold gas of fermionic atoms close to a Feshbach resonance. The correlations are detected by inducing spin-changing rf transitions between pairs of atoms. We observe the process in the strongly interacting regime for attractive as well as for repulsive atom-atom interactions and both in the regime of high and low quantum degeneracy. The observations are compared with a two-particle model that provides theoretical predictions for the measured rf transition rates.

cond-mat.soft↗

arXiv2003

Creation of ultracold molecules from a Fermi gas of atoms

Since the realization of Bose-Einstein condensates (BEC) in atomic gases an experimental challenge has been the production of molecular gases in the quantum regime. A promising approach is to create the molecular gas directly from an ultracold atomic gas; for example, atoms in a BEC have been coupled to electronic ground-state molecules through photoassociation as well as through a magnetic-field Feshbach resonance. The availability of atomic Fermi gases provides the exciting prospect of coupling fermionic atoms to bosonic molecules, and thus altering the quantum statistics of the system. This Fermi-Bose coupling is closely related to the pairing mechanism for a novel fermionic superfluid proposed to occur near a Feshbach resonance. Here we report the creation and quantitative characterization of exotic, ultracold $^{40}$K$_2$ molecules. Starting with a quantum degenerate Fermi gas of atoms at T < 150 nanoKelvin we scan over a Feshbach resonance to adiabatically create over a quarter million trapped molecules, which we can convert back to atoms by reversing the scan. The small binding energy of the molecules is controlled by detuning from the Feshbach resonance and can be varied over a wide range. We directly detect these weakly bound molecules through rf photodissociation spectra that probe the molecular wavefunction and yield binding energies that are consistent with theory.

cond-mat↗

arXiv2002

Tuning p-wave interactions in an ultracold Fermi gas of atoms

We have measured a p-wave Feshbach resonance in a single-component, ultracold Fermi gas of potassium atoms. We have used this resonance to enhance the normally suppressed p-wave collision cross-section to values larger than the background s-wave cross-section between potassium atoms in different spin-states. In addition to the modification of two-body elastic processes, the resonance dramatically enhances three-body inelastic collisional loss.

cond-mat↗

arXiv2001

Resonant control of elastic collisions in an optically trapped Fermi gas of atoms

We have loaded an ultracold gas of fermionic atoms into a far off resonance optical dipole trap and precisely controlled the spin composition of the trapped gas. We have measured a magnetic-field Feshbach resonance between atoms in the two lowest energy spin-states, |9/2, -9/2> and |9/2, -7/2>. The resonance peaks at a magnetic field of 201.5 plus or minus 1.4 G and has a width of 8.0 plus or minus 1.1 G. Using this resonance we have changed the elastic collision cross section in the gas by nearly 3 orders of magnitude.

cond-mat.stat-mech↗