Rabi oscillations and Ramsey-type pulses in ultracold bosons: Role of interactions

TL;DR

This paper investigates how interactions influence Rabi oscillations and Ramsey pulses in ultracold bosonic double-well systems, revealing differences between Raman and lattice couplings through theoretical and experimental analysis.

Contribution

It provides a comparative study of interaction effects in two types of double-well systems created with Bose-Einstein condensates, highlighting the role of scattering diagrams.

Findings

Interactions cause different dynamics in Raman and lattice coupled systems.

Scattering diagrams contribute in lattice systems but not in Raman systems.

Ramsey interference sequences reveal interaction-dependent internal dynamics.

Abstract

Double-well systems loaded with one, two, or many quantum particles give rise to intriguing dynamics, ranging from Josephson oscillation to self-trapping. This work presents theoretical and experimental results for two distinct double-well systems, both created using dilute rubidium Bose-Einstein condensates with particular emphasis placed on the role of interaction in the systems. The first is realized by creating an effective two-level system through Raman coupling of hyperfine states. The second is an effective two-level system in momentum space generated through the coupling by an optical lattice. Even though the non-interacting systems can, for a wide parameter range, be described by the same model Hamiltonian, the dynamics for these two realizations differ in the presence of interactions. The difference is attributed to scattering diagrams that contribute in the lattice coupled system but vanish in the Raman coupled system. The internal dynamics of the Bose-Einstein condensates for both coupling scenarios is probed through a Ramsey-type interference pulse sequence, which constitutes a key building block of atom interferometers. These results have important implications in a variety of contexts including lattice calibration experiments and momentum space lattices used for quantum analog simulations.