Spontaneous formation and relaxation of spin domains in antiferromagnetic spin-1 condensates

Observation of photoassociation spectroscopy of 23Na spinor Bose-Einstein condensate

We report the high-resolution photoassociation (PA) spectroscopy of ²³Na excited from the spin-1 Bose-Einstein Condensate (BEC) to the molecular state of 0g-(P_3/2)v = 4 and 1_g(P_3/2)v = 91. By comparing the PA spectra of different spin configurations, we experimentally studied the effect of spin on the PA spectra. The experimental spectra comply well with the theoretical consideration. The results will play an important role in the study of the spin interaction and control of the antiferromagnetism in Na.

Single-domain Bose condensate magnetometer achieves energy resolution per bandwidth below ℏ

We present a magnetic sensor with energy resolution per bandwidth ER<ℏ. We show how a 87Rb single-domain spinor Bose–Einstein condensate, detected by nondestructive Faraday rotation probing, achieves single-shot low-frequency magnetic sensitivity of 72(8) fT measuring a volume V=1,091(30)  μm3 for 3.5 s, and thus, ER=0.075(16)ℏ. We measure experimentally the condensate volume, spin coherence time, and readout noise and use phase space methods, backed by three-dimensional mean-field simulations, to compute the spin noise. Contributions to the spin noise include one-body and three-body losses and shearing of the projection noise distribution, due to competition of ferromagnetic contact interactions and quadratic Zeeman shifts. Nonetheless, the fully coherent nature of the single-domain, ultracold two-body interactions allows the system to escape the coherence vs. density trade-off that imposes an energy resolution limit on traditional spin precession sensors. We predict that other Bose-condensed alkalis, especially the antiferromagnetic 23Na, can further improve the energy resolution of this method.

Multifaceted phase ordering kinetics of an antiferromagnetic spin-1 condensate

We study phase domain coarsening in the long time limit after a quench of magnetic field in a quasi one-dimensional spin-1 antiferromagnetic condensate. We observe that the growth of correlation length obeys scaling laws predicted by the two different models of phase ordering kinetics, namely the binary mixture and vector field. We derive regimes of clear realization for both of them. We demonstrate appearance of atypical scaling laws, which emerge in intermediate regions.

Observation of Magnetic Solitons in Two-Component Bose-Einstein Condensates

We experimentally investigate the dynamics of spin solitary waves (magnetic solitons) in a harmonically trapped, binary superfluid mixture. We measure the in situ density of each pseudospin component and their relative local phase via an interferometric technique we developed and as such, fully characterize the magnetic solitons while they undergo oscillatory motion in the trap. Magnetic solitons exhibit nondispersive, dissipationless longtime dynamics. By imprinting multiple magnetic solitons in our ultracold gas sample, we engineer binary collisions between solitons of either the same or opposite magnetization and map out their trajectories.

Observation of Dynamical Quantum Phase Transitions with Correspondence in an Excited State Phase Diagram

Dynamical quantum phase transitions are closely related to equilibrium quantum phase transitions for ground states. Here, we report an experimental observation of a dynamical quantum phase transition in a spinor condensate with correspondence in an excited state phase diagram, instead of the ground state one. We observe that the quench dynamics exhibits a nonanalytical change with respect to a parameter in the final Hamiltonian in the absence of a corresponding phase transition for the ground state there. We make a connection between this singular point and a phase transition point for the highest energy level in a subspace with zero spin magnetization of a Hamiltonian. We further show the existence of dynamical phase transitions for finite magnetization corresponding to the phase transition of the highest energy level in the subspace with the same magnetization. Our results open a door for using dynamical phase transitions as a tool to probe physics at higher energy eigenlevels of many-body Hamiltonians.