Abstract Arrays of individual atoms trapped in optical microtraps with micrometer‐scale sizes have emerged as a fundamental, versatile, and powerful platform for quantum sciences and technologies. This platform enables the bottom‐up engineering of quantum systems, offering the capability of low‐entropy preparation of quantum states with flexible geometry, as well as manipulation and detection at the single‐site level. The utilization of ultracold itinerant atoms with tunnel coupling in optical microtraps provides new opportunities for quantum simulation, enabling the exploration of exotic quantum states, phases, and dynamics, which would otherwise be challenging to achieve in conventional optical lattices due to high entropy and limited geometric flexibility. Here, the development of tunnel‐coupled optical microtraps for the manipulation of ultracold atomic quantum systems and its recent advances are briefly reviewed.
Abstract Arrays of individual atoms trapped in optical microtraps with micrometer‐scale sizes have emerged as a fundamental, versatile, and powerful platform for quantum sciences and technologies. This platform enables the bottom‐up engineering of quantum systems, offering the capability of low‐entropy preparation of quantum states with flexible geometry, as well as manipulation and detection at the single‐site level. The utilization of ultracold itinerant atoms with tunnel coupling in optical microtraps provides new opportunities for quantum simulation, enabling the exploration of exotic quantum states, phases, and dynamics, which would otherwise be challenging to achieve in conventional optical lattices due to high entropy and limited geometric flexibility. Here, the development of tunnel‐coupled optical microtraps for the manipulation of ultracold atomic quantum systems and its recent advances are briefly reviewed.
Ultracold atoms in optical lattices are a powerful platform for the study of quantum many-body physics. The combination of a high degree of isolation from the environment and external control over all relevant parameters makes these systems ideal candidates for the quantum simulation of fundamental lattice models. However, since the atoms are trapped in standing waves of interfering laser beams, the available trap geometries are constrained to regular lattices and single-site control is limited. In this thesis, an alternative experimental platform is investigated. Here, the combination of a microlens array and a spatial light modulator is used to provide a two-dimensional optical microtrap array for ultracold atoms. This setup allows for versatile trap geometries and comprehensive single-site control. The experimental feasibility of the described platform is investigated in the following way. First, the light field generating the microtrap array is simulated using a detailed model of the optical setup. The computed intensity distribution is proportional to the optical dipole potential for the atoms. Second, the simulation results are used to obtain the Hubbard parameters for multiple alkalies from numerical calculations as well as approximative analytical methods. It is shown that the strongly correlated regimes of the Bose-Hubbard model can be reached at sufficiently large tunneling rates. In addition, the impact of fluctuations in the trap parameters is investigated. Third, two approaches are considered for the preparation of low-entropy many-body states. On the one hand, a loading scheme is investigated which starts from a Bose-Einstein condensate and is used in optical lattice experiments. Here, the depth of the microtrap array is increased adiabatically. On the other hand, an array of isolated traps, which is initialized with one atom per site in the respective motional ground state, is considered as starting point. The itinerant regime of the Hubbard model is accessed by an adiabatic decrease of the trap depth. An analysis of ramp-induced excitations and external heating processes shows the feasibility of both approaches. Demonstrating the potential of the investigated platform, two applications are described. On the one hand, the tunneling dynamics of ultracold atoms between weakly coupled ring lattices is analyzed. Controlled by the interaction strength, multiple phenomena can be observed: Josephson oscillations exhibiting collapse and revival, inter-action-induced self-trapping, and tunneling resonances. On the other hand, the implementation of a scheme for universal quantum computing based on time-continuous quantum walks of interacting particles is proposed. Here, the information is encoded into the position of atomic wave packets moving through a planar graph which is built from optical microtraps and implements a quantum circuit. Details of an experimental implementation are discussed for both applications using the results derived in the preceding parts of this thesis.
Owing to rapid recent progress, ultracold atomic lattice systems for simulating topological phases are now at a pivotal stage, evolving from established paradigms into increasingly versatile and programmable quantum simulators. In this review, we survey recent experimental advances across four major classes of platforms: optical lattices, including optical lattices with laser-assisted tunneling and optical Raman lattices; synthetic lattices in momentum or internal-state space; Floquet-engineered lattices; and optical tweezer arrays, all of which offer distinct capabilities for realizing and probing topological matter. For each class, we highlight representative experimental breakthroughs, the topological models that have been realized, and the advanced detection and characterization techniques employed, emphasizing how these complementary approaches collectively expand the frontier of quantum simulation. We also discuss emerging directions in strongly correlated and nonequilibrium topological phases, and conclude with an outlook on future prospects.
Engineered ultracold atomic systems are a valuable platform for fundamental quantum mechanics studies and the development of quantum technologies. At near zero absolute temperature, atoms exhibit macroscopic phase coherence and collective quantum behavior, enabling their use in precision metrology, quantum simulation, and even information processing. This review provides an introductory overview of the key techniques used to trap, manipulate, and detect ultracold atoms, while highlighting the main applications of each method. We outline the principles of laser cooling, magnetic and optical trapping, and the most widely used techniques, including optical lattices and tweezers. Next, we discuss the manipulation methods of atomic internal and external degrees of freedom, and we present atom interferometry techniques and how to leverage and control interatomic interactions. Next, we review common ensemble detection strategies, including absorption and fluorescence imaging, state-selective readout, correlation and quantum non-demolition measurements and conclude with high-resolution approaches. This review aims to provide newcomers to the field with a broad understanding of the experimental toolkit that underpins research in ultracold atom physics and its applications across quantum science and technology.
Ultracold atoms confined in microtrap array is a highly versatile platform for quantum many-body physics, quantum simulation and quantum computation because of the easy scalability, long coherence time, single site addressability and controllable interactions, e.g. using Rydberg states. Here, we demonstrate an novel method to prepare versatile arrays of atomic ensembles by transferring them from a pancake shaped optical reservoir to an array of optical tweezers produced via direct projection of light patterns produced via a digital micromirror device. The size of each ensemble is smaller than the Rydberg blockade radius, such that each one can carry either 0 or 1 (collective) excitations which can then strongly interact with the neighbouring ensembles. Finally I will discuss a recent proposal to use such Rydberg arrays to realise programmable quantum systems in the form of quantum cellular automata (QCA). This opens a path to study many-body quantum dynamics in quantum and classical regimes, to engineer highly entangled quantum states and toward an inherently scalable approach to quantum information processing and computing.
In recent years, ultracold atoms trapped in periodic lattices have attracted much attention as a simulator for condensed matter systems because of the ability to manipulate and precisely control the ultracold atoms. Periodic arrays of magnetic microtraps patterned on a magnetic film provide a potential complementary tool to conventional optical lattices for trapping arrays of ultracold atoms. Compared to optical lattices, magnetic lat- tices allow a higher degree of design flexibility by allowing almost arbitrary lattice geometries and they also allow lower technical noise and state-selective trapping of atoms. This paper reports the trapping of ultracold 87Rb atoms in 0.7 μm-period triangular and square magnetic lattices integrated on an atom chip as a step towards using magnetic lattices as a new platform for simulating condensed matter and quantum many-body phenomena in nontrivial lattice geometries.
Trapped neutral atoms are one of the leading platforms for quantum information technologies, in particular for quantum computing, but scaling them to array sizes needed for utility-scale quantum computing is a major engineering challenge. Here we review optical metasurfaces as an enabling technology that provides fine control over the phase, amplitude, and polarization of light, with pixel counts far exceeding what is available with spatial light modulators (SLMs) and other active devices. The large pixel counts have recently led to demonstrations of arrays of optical tweezers with hundreds of thousands of sites and arrays of optical bottle-beams with complex three-dimensional trapping profiles. The flexibility and scalability of optical metasurfaces provides a route towards miniaturized, integrated, and highly scalable atomic experiments and instruments.