arXiv subjects

E. L. Bolda

Publications and source records attributed to E. L. Bolda.

4 recordsLinked to original sources

arXiv2003

Quantum State Control via Trap-induced Shape Resonance in Ultracold Atomic Collisions

We investigate controlled collisions between trapped but separated ultracold atoms. The interaction between atoms is treated self-consistently using an energy-dependent delta-function pseudopotential model, whose validity we establish. At a critical separation, a "trap-induced shape resonance" between a molecular bound states and a vibrational eigenstate of the trap can occur. This resonance leads to an avoided crossing in the eigenspectrum as a function of separation. We investigate how this new resonance can be employed for quantum control.

quant-ph↗

arXiv2003

Pseudopotential model of ultracold atomic collisions in quasi-one- and two-dimensional traps

We describe a model for s-wave collisions between ground state atoms in optical lattices, considering especially the limits of quasi-one and two dimensional axisymmetric harmonic confinement. When the atomic interactions are modelled by an s-wave Fermi-pseudopotential, the relative motion energy eigenvalues can easily be obtained. The results show that except for a bound state, the trap eigenvalues are consistent with one- and two- dimensional scattering with renormalized scattering amplitudes. For absolute scattering lengths large compared with the tightest trap width, our model predicts a novel bound state of low energy and nearly-isotropic wavefunction extending on the order of the tightest trap width.

quant-ph↗

arXiv2002

Self-consistent model of ultracold atomic collisions and Feshbach resonances in tight harmonic traps

We consider the problem of cold atomic collisions in tight traps, where the absolute scattering length may be larger than the trap size. As long as the size of the trap ground state is larger than a characteristic length of the van der Waals potential, the energy eigenvalues can be computed self-consistently from the scattering amplitude for untrapped atoms. By comparing with the exact numerical eigenvalues of the trapping plus interatomic potentials, we verify that our model gives accurate eigenvalues up to milliKelvin energies for single channel s-wave scattering of $^{23}$Na atoms in an isotropic harmonic trap, even when outside the Wigner threshold regime. Our model works also for multi-channel scattering, where the scattering length can be made large due to a magnetically tunable Feshbach resonance.

physics.atom-ph↗

arXiv1998

Superluminal Signals: Causal Loop Paradoxes Revisited

Recent results demonstrating superluminal group velocities and tachyonic dispersion relations reopen the question of superluminal signals and causal loop paradoxes. The sense in which superluminal signals are permitted is explained in terms of pulse reshaping, and the self-consistent behavior which prevents causal loop paradoxes is illustrated by an explicit example.

quant-ph↗