An atom-by-atom assembler of defect-free arbitrary two-dimensional atomic arrays

Abstract

Large arrays of individually controlled atoms trapped in optical tweezers are a very promising platform for quantum engineering applications. However, to date, only disordered arrays have been demonstrated, due to the non-deterministic loading of the traps. Here, we demonstrate the preparation of fully loaded, two-dimensional arrays of up to ∼ 50 microtraps each containing a single atom, and arranged in arbitrary geometries. Starting from initially larger, half-filled matrices of randomly loaded traps, we obtain user-defined target arrays at unit filling. This is achieved with a real-time control system and a moving optical tweezers that performs a sequence of rapid atom moves depending on the initial distribution of the atoms in the arrays. These results open exciting prospects for quantum engineering with neutral atoms in tunable geometries.The last decade has seen tremendous progress over the control of individual quantum objects [1, 2]. Many experimental platforms, from trapped ions [3] to superconducting qubits [4], are actively explored. The current challenge is now to extend these results towards large assemblies of such objects, while keeping the same degree of control, in view of applications in quantum information processing [5], quantum metrology [6], or quantum simulation [7]. Neutral atoms offer some advantages over other systems for these tasks. Besides being well isolated from the environment and having tunable interactions, systems of cold atoms hold the promise of being scalable to hundreds of individually controlled qubits. Control of the atomic positions at the single-particle level can been achieved with optical potentials. In a 'top-down' approach using optical lattices and quantum gas microscopes, hundreds of traps can now be created and addressed individually [8]. By making use of the superfluid to Mott-insulator transition, single atom filling fractions exceeding 90% are achieved [9], albeit at the expense of relatively long experimental duty cycles and constraints in the lattice geometries.Single atoms can also be trapped in 2d arrays of microscopic optical tweezers with single-site resolution using holographic methods [10][11][12]. This bottom-up approach offers faster preparation and a higher degree of tunability of the underlying geometry. However, achieving unit filling of the arrays is hampered by the stochastic nature of the loading and has remained so far elusive. Although proof-of-principle demonstrations of quantum gates [13] and quantum simulations [14] using this latter platform have been reported [15], this non-deterministic loading poses a serious limitation for applications where large-scale ordered arrays are required. To solve this problem, several approaches have been considered, exploiting the Rydberg blockade mechanism [16], or using tailored light-assisted collisions [17]. To date, despite those efforts, loading efficiencies of around 90% at best for a single atom in a single tweezers could be achieved [18,19], making the probabilities to fully load large arrays still...

Tunable-Range, Photon-Mediated Atomic Interactions in Multimode Cavity QED

“…Wiring the network to implement a particular graphical combinatorial optimization problem simply involves placing the atoms in specific locations within the cavity modes. This may be possible with optical tweezer arrays [59,60]. The combination of local and nonlocal interactions demonstrated here will enable the construction of a wide variety of graphical combinatorial optimization problems, not just those of a complete graph.…”

Optical Control of the Resonant Dipole-Dipole Interaction between Rydberg Atoms

“…In addition, arrays of optical tweezers allow the efficient preparation of assemblies of up to 50 atoms, arranged in arbitrary geometries, as has been recently demonstrated [19,20]. One can encode a spin-1/2 between the ground-state and a Rydberg level, use the van der Waals interactions between two identical Rydberg states and map the system onto an Ising-like Hamiltonian [21].…”

Quantum simulators by design: Many-body physics in reconfigurable arrays of tunnel-coupled traps

“…2) The dynamic control over local potential depths can be utilized for Floquet engineering [33,41] with modulation frequencies of up to 10 kHz, fully adjustable modulation amplitudes, and single-site addressability. 3) A promising alternative to the loading schemes starting with BECs arises from the implementation of Raman side-band cooling in individual traps [11,12] with the targeted many-body state assembled atom by atom [15][16][17] out of the low entropy Mott-insulator phase. This facilitates studies of the many-body physics of atomic species, which are not accessible to BEC, or arbitrary mixtures of species.…”

“…Compared to state of the art holographic trap arrays generated by phase modulating spatial light modulators [15,17], it accesses the tunneling regime and omits pixelation constraints imposed to trap spacing, homogeneity and system size. With regard to potentials generated by acousto-optics through multi-tone synthesis [16] or time-averaging [22], it is scalable and avoids additional heating.…”

“…In combination with acoustooptic deflectors and spatial light modulators (SLM) this approach has been extended to few-well configurations showing tunnel-coupling [13,14] on one side and the deterministic preparation of larger defect-free 1D and 2D arrays with spacing too large for tunneling on the other side [15][16][17].…”