Nonequilibrium Quantum Magnetism in a Dipolar Lattice Gas

Abstract

We report on the realization of quantum magnetism using a degenerate dipolar gas in an optical lattice. Our system implements a lattice model resembling the celebrated t-J model. It is characterized by a nonequilibrium spinor dynamics resulting from intersite Heisenberg-like spin-spin interactions provided by nonlocal dipole-dipole interactions. Moreover, due to its large spin, our chromium lattice gases constitute an excellent environment for the study of quantum magnetism of high-spin systems, as illustrated by the complex spin dynamics observed for doubly occupied sites.

Entanglement and fluctuations in the XXZ model with power-law interactions

“…Indeed the Hamiltonian (1) with α = 3 in d = 2 is realized by the Mott insulating phase of magnetic atoms [8] when imposing the conservation of the magnetization along the quantization axis. Furthermore its d = 1 implementation can be envisioned in trapped ions [3,64], which also enable to vary continuously the α exponent of the power-law decay of interactions.…”

“…Within this setup, experimentalists were able to observe how the dynamics of correlation spreading after a quantum quench is modified by the long-range interactions with respect to the case of ultracold neutral atoms interacting via a contact potential [6]. Within the context of ultracold neutral gases several groups have attained the quantum degeneracy of atoms possessing a large intrinsic magnetic moment, namely fermionic and bosonic isotopes of Cr [7][8][9], Dy [10,11] and Er [12,13], and they were able to observe the coherent spin-exchange dynamics in these systems, induced by the large dipole-dipole (1/r 3 ) interaction [8,14]. Moreover infinite-range cavity-mediated interactions in a Bose-Einstein condensate have been experimentally demonstrated [15,16], leading to the spontaneous formation of long-range ordered phases (solid and supersolid).…”

Landau Levels in Strained Optical Lattices

“…At 2=3 filling of the zeroth Landau level, tuning the ratio of long and short range interactions is predicted to drive the formation of a triplet superfluid, a fractional topological insulator, and the 2=3 fractional quantum Hall effect [6]. In comparison to natural graphene, our proposal gives the advantages of (1) better control over the strain patterns and (2) control over both short [5] and long-rang interactions (using methods based on Rydberg atoms [44], dipolar atoms [45], or dipolar molecules [46]) and (3) control over filling factors, and (4) the availability of low disorder potentials, making it particularly promising for realizing these exotic phases.…”

Two-dimensional superexchange-mediated magnetization dynamics in an optical lattice

“…However, the perturbative origin of superexchange in these systems requires that it be weak compared to tunneling, and thus the manifestation of superexchange requires extremely low motional entropy. Dipolar gases [10] and ultracold polar molecules [11] in lattices provide a promising route toward achieving large (non-perturbative) magnetic interactions [12], but, technical limitations in these systems currently complicate the simultaneous observation of motional and spin-exchange effects.Here, we study the magnetization dynamics of effective spin-1/2 bosons in a 2D optical lattice following a global quench from an initially antiferromagnetically ordered state [13]. The dynamics we observe is governed by a bosonic t-J model [14,15].…”

“…However, the perturbative origin of superexchange in these systems requires that it be weak compared to tunneling, and thus the manifestation of superexchange requires extremely low motional entropy. Dipolar gases [10] and ultracold polar molecules [11] in lattices provide a promising route toward achieving large (non-perturbative) magnetic interactions [12], but, technical limitations in these systems currently complicate the simultaneous observation of motional and spin-exchange effects.…”