Coherent spinor dynamics in all-optical spin-1 condensates

M.-S. Chang, Qishu Qin, Wenxian Zhang +2 more

M.-S. Chang

Bose-Einstein condensation (BEC) is a phenomenon in which identical bosons occupy the same quantum state below a certain critical temperature. A hallmark of BEC is the coherence between particles every particle shares the same quantum wavefunction and phase. This coherence has been demonstrated for the external (motional) degrees of freedom of the atomic condensates by interfering two condensates. In this thesis, the coherence is shown to extend to the internal spin degrees of freedom of a spin-1 Bose gas evidenced by the observed coherent and reversible spin-changing collisions. The observed coherent dynamics are analogous to Josephson oscillations in weakly connected superconductors and represent a type of matter-wave four-wave mixing. Control of the coherent evolution of the system using magnetic fields is also demonstrated. The studies on spinor condensates begin by creating spinor condensates directly using all-optical approaches that were first developed in our laboratory. All-optical formation of Bose-Einstein condensates (BEC) in 1D optical lattice and single focus trap geometries are developed and presented. These techniques offer considerable flexibility and speed compared to magnetic trap approaches, and the trapping potential can be essentially spin-independent and are ideally suited for studying spinor condensates. Using condensates with well-defined initial non-equilibrium spin configuration, spin mixing of F = 1 and F = 2 spinor condensates of rubidium-87 atoms confined in an optical trap is observed. The equilibrium spin configuration in the F = 1 manifold confirms that 87Rb is ferromagnetic. The coherent spinor dynamics are demonstrated by initiating spin mixing deterministically with a non-stationary spin population configuration. Finally, the interplay between the coherent spin mixing and spatial dynamics in spin-1 condensates with ferromagnetic interactions is investigated.

Zhi Li, Ai‐Xia Zhang, Juan Ma +1 more

N. Lundblad, R. J. Thompson, D. C. Aveline +1 more

We demonstrate a novel dual-beam atom laser formed by outcoupling oppositely polarized components of an all-optical F = 1 spinor Bose-Einstein condensate whose Zeeman sublevel populations have been coherently evolved through spin dynamics. The condensate is formed through all-optical means using a single-beam running-wave dipole trap. We create a condensate in the magnetic field-insensitive m(F) = 0 state, and drive coherent spin-mixing evolution through adiabatic compression of the initially weak trap. Such dual beams, number-correlated through the angular momentum-conserving reaction 2m(0) ?m(+1) +m(-1), have been proposed as tools to explore entanglement and squeezing in Bose-Einstein condensates, and have potential use in precision phase measurements.

Hardesty-Shaw, Zachary N.

A Bose Einstein Condensate (BEC) is an extraordinarily versatile state of matterthat allows for the simulation of quantum phenomena on the macroscopic scale. This powerful platform features rich physics such as superfluidity, quantum phase coherence, long range order, and spontaneous symmetry breaking. A spinor BEC, or a BEC with a spin degree of freedom, in particular is highly controllable as a quantum simulator, especially under the application of customizable optical lattices. In this thesis I present a study of spinor BECs in moving optical lattices. The results of this thesis open the way for the exploitation of not only quantum based properties of a BEC, but also the classical spatial dynamics inherit to the system for simulating many-body quantum spin dynamics with highly tunable, time-dependent interactions.

Weiping Zhang, Han Pu, Christopher P. Search +1 more