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Register a new userEmergence of multi-body interactions in few-atom sites of a fermionic lattice clock
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Alkaline-earth (AE) atoms have metastable clock states with minute-long optical lifetimes, high-spin nuclei, and SU($N$)-symmetric interactions that uniquely position them for advancing atomic clocks, quantum information processing, and quantum simulation. The interplay of precision measurement and quantum many-body physics is beginning to foster an exciting scientific frontier with many opportunities. Few particle systems provide a window to view the emergence of complex many-body phenomena arising from pairwise interactions. Here, we create arrays of isolated few-body systems in a fermionic ${}^{87}$Sr three-dimensional (3D) optical lattice clock and use high resolution clock spectroscopy to directly observe the onset of both elastic and inelastic multi-body interactions. These interactions cannot be broken down into sums over the underlying pairwise interactions. We measure particle-number-dependent frequency shifts of the clock transition for atom numbers $n$ ranging from 1 to 5, and observe nonlinear interaction shifts, which are characteristic of SU($N$)-symmetric elastic multi-body effects. To study inelastic multi-body effects, we use these frequency shifts to isolate $n$-occupied sites and measure the corresponding lifetimes. This allows us to access the short-range few-body physics free from systematic effects encountered in a bulk gas. These measurements, combined with theory, elucidate an emergence of multi-body effects in few-body systems of sites populated with ground-state atoms and those with single electronic excitations. By connecting these few-body systems through tunneling, the favorable energy and timescales of the interactions will allow our system to be utilized for studies of high-spin quantum magnetism and the Kondo effect.
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Trapped Rydberg ions represent a flexible platform for quantum simulation and information processing which combines a high degree of control over electronic and vibrational degrees of freedom. The possibility to individually excite ions to high-lying Rydberg levels provides a system where strong and long-range interactions between pairs of excited ions can be engineered and tuned via external laser fields. We show that the coupling between Rydberg pair interactions and collective motional modes gives rise to effective long-range multi-body interactions, consisting of two, three, and four-body terms. Their shape, strength, and range can be controlled via the ion trap parameters and strongly depends on both the equilibrium configuration and vibrational modes of the ion crystal. By focusing on an experimentally feasible quasi one-dimensional setup of $ {}^{88}mathrm{Sr}^+ $ Rydberg ions, we demonstrate that multi-body interactions are enhanced by the emergence of a soft mode associated, e.g., with a structural phase transition. This has a striking impact on many-body electronic states and results, for example, in a three-body anti-blockade effect. Our study shows that trapped Rydberg ions offer new opportunities to study exotic many-body quantum dynamics driven by enhanced multi-body interactions.
We present a unifying theoretical framework that describes recently observed many-body effects during the interrogation of an optical lattice clock operated with thousands of fermionic alkaline earth atoms. The framework is based on a many-body master equation that accounts for the interplay between elastic and inelastic p-wave and s-wave interactions, finite temperature effects and excitation inhomogeneity during the quantum dynamics of the interrogated atoms. Solutions of the master equation in different parameter regimes are presented and compared. It is shown that a general solution can be obtained by using the so called Truncated Wigner Approximation which is applied in our case in the context of an open quantum system. We use the developed framework to model the density shift and decay of the fringes observed during Ramsey spectroscopy in the JILA 87Sr and NIST 171Yb optical lattice clocks. The developed framework opens a suitable path for dealing with a variety of strongly-correlated and driven open-quantum spin systems.
We demonstrate fluorescence microscopy of individual fermionic potassium atoms in a 527-nm-period optical lattice. Using electromagnetically induced transparency (EIT) cooling on the 770.1-nm D$_1$ transition of $^{40}$K, we find that atoms remain at individual sites of a 0.3-mK-deep lattice, with a $1/e$ pinning lifetime of $67(9),rm{s}$, while scattering $sim 10^3$ photons per second. The plane to be imaged is isolated using microwave spectroscopy in a magnetic field gradient, and can be chosen at any depth within the three-dimensional lattice. With a similar protocol, we also demonstrate patterned selection within a single lattice plane. High resolution images are acquired using a microscope objective with 0.8 numerical aperture, from which we determine the occupation of lattice sites in the imaging plane with 94(2)% fidelity per atom. Imaging with single-atom sensitivity and addressing with single-site accuracy are key steps towards the search for unconventional superfluidity of fermions in optical lattices, the initialization and characterization of transport and non-equilibrium dynamics, and the observation of magnetic domains.
We experimentally investigate a scheme for studying lattice transport phenomena, based on the controlled momentum-space dynamics of ultracold atomic matter waves. In the effective tight-binding models that can be simulated, we demonstrate that this technique allows for a local and time-dependent control over all system parameters, and additionally allows for single-site resolved detection of atomic populations. We demonstrate full control over site-to-site off-diagonal tunneling elements (amplitude and phase) and diagonal site-energies, through the observation of continuous-time quantum walks, Bloch oscillations, and negative tunneling. These capabilities open up new prospects in the experimental study of disordered and topological systems.
We show that four heavy fermions interacting resonantly with a lighter atom (4+1 system) become Efimovian at mass ratio 13.279(2), which is smaller than the corresponding 2+1 and 3+1 thresholds. We thus predict the five-body Efimov effect for this system in the regime where any of its subsystem is non- Efimovian. For smaller mass ratios we show the existence and calculate the energy of a universal 4+1 pentamer state, which continues the series of the 2+1 trimer predicted by Kartavtsev and Malykh and 3+1 tetramer discovered by Blume. We also show that the effective-range correction for the light-heavy interaction has a strong effect on all these states and larger effective ranges increase their tendency to bind.
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