Probing site-resolved correlations in a spin system of ultracold molecules

Abstract

Synthetic quantum systems with interacting constituents play an important role in quantum information processing and in elucidating fundamental phenomena in many-body physics. Following impressive advances in cooling and trapping techniques, ensembles of ultracold polar molecules have emerged as a promising synthetic system that combines several advantageous properties [1][2][3][4][5][6][7][8][9][10][11]. These include a large set of internal states for encoding quantum information, long nuclear and rotational coherence times [12][13][14][15][16][17] and long-range, anisotropic interactions. The latter are expected to allow the exploration of intriguing phases of correlated quantum matter, such as topological superfluids [18], quantum spin liquids [19], fractional Chern insulators [20] and quantum magnets [21,22]. Probing correlations in these phases is crucial to understand their microscopic properties, necessitating the development of new experimental techniques. Here we use quantum gas microscopy [23] to measure the site-resolved dynamics of quantum correlations in a gas of polar molecules in a two-dimensional optical lattice. Using two rotational states of the molecules, we realize a spin-1/2 system where the particles are coupled via dipolar interactions, producing a quantum spin-exchange model [21,22,24,25]. Starting with the synthetic spin system prepared far from equilibrium, we study the evolution of correlations during the thermalization process for both spatially isotropic and anisotropic interactions. Furthermore, we study the correlation dynamics in a spin-anisotropic Heisenberg model engineered from the native spin-exchange model using Floquet techniques [26][27][28]. These experiments push the frontier of probing and controlling interacting systems of ultracold molecules, with prospects for exploring new regimes of quantum matter and characterizing entangled states useful for quantum computation [29,30] and metrology [31].

Continuous symmetry breaking in a two-dimensional Rydberg array

“…Synthetic quantum systems are ideally suited to study these features. While ultra-cold atoms in optical lattices have investigated continuous symmetry breaking with contact interaction [28], dipolar molecules in lattices [29][30][31][32] or trapped ions [33][34][35][36] are promising platforms to realize the long-range case. Here, we use a Rydberg quantum simulator to realize a long-range interacting, two-dimensional XY spin system with either ferromagnetic (FM) or antiferromagnetic (AFM) couplings.…”

Atomic physics on a 50 nm scale: Realization of a bilayer system of dipolar atoms

“…We are currently applying the super-resolution technique to optical tweezers to place two atoms at 50 nm scale separation. This will allow the study of superradiance and radiative shifts at separations much smaller than the optical wavelength, and the study of magnetic interactions and spin exchange between two isolated atoms, as done recently with polar molecules [53][54][55][56]. The tweezer setup can be generalized to a linear array of atoms alternating in spin-up and spin-down states.…”

Continuous Symmetry Breaking in a Two-dimensional Rydberg Array

“…Even when order persists in both the short-and long-range cases, the nature of this order, including the dispersion of excitations or the decay of correlation functions, can be fundamentally distinct [24,31]. Here, we investigate continuous symmetry breaking in a long-range interacting, two-dimensional XY magnet with either ferromagnetic (FM) or antiferromagnetic (AFM) couplings [32][33][34][35][36][37].…”