Frustrated quantum magnetism with Bose gases in triangular optical lattices at negative absolute temperatures

Abstract

We propose an experimental protocol to perform analog quantum simulation of frustrated antiferromagnetism with strong quantum fluctuations by using ultracold Bose gases in triangular optical lattices with isosceles anisotoropy of hoppings. Specifically, we combine a phase-imprinting scheme with sudden sign inversion of the interatomic interaction and the trap potential to prepare a chiral superfluid state with a negative absolute temperature. In the framework of the time-dependent Gutzwiller approach, we compute the time evolution of the state subjected to a slow sweep of the hopping energy. We show that in this process the system simulates a state near equilibrium of the Bose-Hubbard model with sign-inverted hoppings. By means of the cluster mean-field method with a cluster size scaling, we quantitatively predict the quantum critical point of the superfluid-Mott insulator transition as a function of the spatial anisotropy parameter, which serves as a benchmark for quantum simulation.

Single-site-resolved imaging of ultracold atoms in a triangular optical lattice

“…Thus, a more robust deconvolution algorithm is required. Although the present experiment has been performed for 87 Rb atoms, our method can be extended to 85 Rb atoms, for which the interatomic interaction can be adjusted with a broad, low-field Feshbach resonance [31] for realising antiferromagnetic super-exchange coupling [32,33] or antiferromagnetic coupling through negative absolute temperature [8].…”

“…The simulation of classical magnets of frustrated systems has been demonstrated using Bose-Einstein condensates in a triangular optical lattice [4]. Further, theoretical proposals for the quantum simulation of frustrated quantum magnetism have been reported [5,6,7,8]. However, several technical challenges, such as the preparation of a low-entropy state, need to be overcome to realise frustrated quantum magnets in ultracold-atom experiments.…”

Formation of Matter-Wave Droplet Lattices in Multi-Color Periodic Confinements

“…Different engineered forms of OL geometries such as bi-periodic, kagome, hexagonal, double-well superlattices, etc., are regularly experimentally realized by interfering different sets of laser beams [17]. A number of interesting physical phenomena have been reported in the presence of the above-mentioned geometrically frustrated OLs, including frustrated quantum magnetism at negative absolute temperature [18], many-body localization [19], the exploration of the ionic Hubbard model with ultracold fermions [20], and Hund's metal in multicomponent Fermi systems [21].…”

Cluster mean field plus density matrix renormalization theory for the Bose Hubbard models

“…However, there are limitations in forming more extensive cluster sizes as the Hilbert space of the cluster increases exponentially with the number of sites. There has been recent reports of overcoming this limitation to build larger cluster sizes using the cluster meanfield method with DMRG [31][32][33][34][35][36].…”