The presented thesis reports on the development of a broadly applicable, open-source, modular system architecture for quantum gas experiments, which has been named Heidelberg Quantum Architecture (HQA). In the ongoing rollover of quantum gas apparatuses from mere experiments to usable platforms for quantum simulation, similar to classical computing in the 1950s, such an architecture can be beneficial in the pursuit of improving the usability and raising the technology readiness level (TRL) of these systems. An exemplary quantum gas apparatus for quantum simulation with ultracold 6 Li, follow- ing the guidelines of HQA, is constructed. It is named Heidelberg Quantum Architecture based experiment described in this thesis (HQA-ONE). The modular concept of Heidel- berg Quantum Architecture (HQA), which disentangles the complexity of the quantum gas apparatus into subsystems that are attached to a common mechanical frame of reference (FOR), is demonstrated. A passive interfacing precision of the exchangeable modules mounted to the framework of around ±10µm is measured. The reconfigurable apparatus HQA-ONE is equipped with modules for deterministic preparation of atom number states in the ground state of an optical tweezer to exemplarily demonstrate a core capability of quantum simulators, quantum state initialization, with the apparatus and indirectly with the platform. Further modules to choose from when configuring the apparatus for quantum simulations in the future are developed, constructed, and presented in the thesis, underlining the reconfiguration character of the platform and its versatility.
The presented thesis reports on the development of a broadly applicable, open-source, modular system architecture for quantum gas experiments, which has been named Heidelberg Quantum Architecture (HQA). In the ongoing rollover of quantum gas apparatuses from mere experiments to usable platforms for quantum simulation, similar to classical computing in the 1950s, such an architecture can be beneficial in the pursuit of improving the usability and raising the technology readiness level (TRL) of these systems. An exemplary quantum gas apparatus for quantum simulation with ultracold 6 Li, follow- ing the guidelines of HQA, is constructed. It is named Heidelberg Quantum Architecture based experiment described in this thesis (HQA-ONE). The modular concept of Heidel- berg Quantum Architecture (HQA), which disentangles the complexity of the quantum gas apparatus into subsystems that are attached to a common mechanical frame of reference (FOR), is demonstrated. A passive interfacing precision of the exchangeable modules mounted to the framework of around ±10µm is measured. The reconfigurable apparatus HQA-ONE is equipped with modules for deterministic preparation of atom number states in the ground state of an optical tweezer to exemplarily demonstrate a core capability of quantum simulators, quantum state initialization, with the apparatus and indirectly with the platform. Further modules to choose from when configuring the apparatus for quantum simulations in the future are developed, constructed, and presented in the thesis, underlining the reconfiguration character of the platform and its versatility.
We report on the development of a modular platform for programmable quantum simulation with atomic quantum gases. The platform is centered around exchangeable optical modules with versatile functionalities. The performance of each module is disentangled from all others, enabling individual validation and maintenance of its outputs. The relative spatial positioning of the modules with respect to the position of the atomic sample is set by a global reference frame. In this way, the platform simplifies reconfiguration and upgrading of existing setups and accelerates the design of new machines in a time- and cost-efficient manner. Furthermore, it facilitates collaborations between different experimental groups. This standardized hardware design framework, which we call Heidelberg Quantum Architecture, paves the way towards a new generation of on-demand and highly adaptable quantum simulation experiments.
In this thesis, we present the first experimental results obtained from a newly developed modular quantum gas platform. The platform features exchangeable optical modules that can be individually characterized and maintained, enabling rapid reconfiguration with modules of diverse functionality. We configure the platform to carry out first quantum simulation experiments using fermionic Li-6 in optical tweezers. In particular, we realize motional ground-state systems in a one-dimensional optical tweezer, demonstrate the preparation of spin-imbalanced systems, explore scaling to multiple tweezers, and extend the system to a tunnel-coupled double well, realizing experimental cycle times as short as 800 ms. We further present the development of a novel free-space fluorescence imaging technique, which utilizes the polarization degree of freedom of the emitted photons to encode spin information. This method extends established free-space fluorescence imaging methods both conceptually and technically, and facilitates their application across a broad range of quantum gas experiments. Finally, we report on the first realization of optical shielding in Li-6, with observed light shifts on the GHz scale. We find that, due to the internal structure of Li-6, theoretical descriptions used for other systems are no longer sufficient to describe such light shifts. We therefore develop a novel theoretical model based on the numerical diagonalization of the strongly coupled multilevel Hamiltonian describing states in the 2p_1/2 , 2p_3/2 , and 3s_1/2 manifolds of Li-6. This model allows for a quantitative description of state-dependent light shifts and provides a foundation for the precise engineering of energy levels. We utilize the differential light shift to achieve high-fidelity shielding of quantum ground state systems from imaging, thereby demonstrating the ability to locally address and measure cold atomic quantum systems of Li-6. This capability for local control and measurement enables the implementation of a broad range of quantum simulation experiments.
A frontier challenge in quantum science and technology is the construction of scalable quantum systems which can operate in regimes beyond classical simulatability. Such systems can be used as tools for simulating and exploring complex phenomena in quantum physics; they can also be used to benchmark and test quantum algorithms. Several experimental platforms, based on a variety of quantum mechanical building blocks, are currently being pursued with these goals in mind, with state-of-the-art systems capable of controlling up to around fifty particles. In this thesis, we present the development of a new platform based on individually controlled neutral atoms. In this approach, hundreds of individual atoms are trapped in an array of optical tweezers, and they are sorted in real-time into programmable geometries in one and two dimensions. After initialization of an array, atom interactions are switched on by coherent excitation to highly excited Rydberg states, resulting in a rich spin Hamiltonian. We experimentally advance several key aspects of this platform, developing new tools for controlling strongly interacting atom arrays and probing novel quantum phases and non-equilibrium dynamics. We additionally utilize Rydberg interactions to entangle atoms, demonstrating high fidelity universal quantum logic gates as well as the preparation of fully entangled Schrödinger cat states. This work highlights the prospects for scalable quantum simulation and quantum information processing beyond the limit of classical computation using neutral atom arrays.
One of the main aims in the field of quantum simulation is to achieve a quantum speedup, often referred to as "quantum computational supremacy," referring to the experimental realization of a quantum device that computationally outperforms classical computers.In this work, we show that one can devise versatile and feasible schemes of two-dimensional, dynamical, quantum simulators showing such a quantum speedup, building on intermediate problems involving nonadaptive, measurement-based, quantum computation.In each of the schemes, an initial product state is prepared, potentially involving an element of randomness as in disordered models, followed by a short-time evolution under a basic translationally invariant Hamiltonian with simple nearest-neighbor interactions and a mere sampling measurement in a fixed basis.The correctness of the final-state preparation in each scheme is fully efficiently certifiable.We discuss experimental necessities and possible physical architectures, inspired by platforms of cold atoms in optical lattices and a number of others, as well as specific assumptions that enter the complexity-theoretic arguments.This work shows that benchmark settings exhibiting a quantum speedup may require little control, in contrast to universal quantum computing.Thus, our proposal puts a convincing experimental demonstration of a quantum speedup within reach in the near term.
Quantum constraint systems are crucial for designing complex quantum circuits, particularly in areas like quantum simulations and quantum algorithm development. However, existing constraint systems often suffer from limitations in scalability and flexibility. This paper introduces the Modular Quantum Constraint System (MQCS), a novel system designed to overcome these challenges by providing a modular approach to constraint design. The MQCS facilitates the creation and manipulation of modular quantum constraint systems, enabling the design of complex quantum circuits with greater flexibility and adaptability. The system's core mechanism revolves around a library of pre-built constraint modules, allowing users to combine and adapt these modules to construct diverse circuits. This research explores the design and implementation of MQCS, focusing on its ability to support a wide range of constraint types and offer enhanced design capabilities. We present the system's architecture, discuss its advantages, and outline potential future directions. The aim is to provide a robust and extensible framework for quantum constraint design, ultimately empowering researchers and engineers to explore novel quantum circuit designs.
Quantum simulators are a promising technology on the spectrum of quantum devices from specialized quantum experiments to universal quantum computers. These quantum devices utilize entanglement and many-particle behaviors to explore and solve hard scientific, engineering, and computational problems. Rapid development over the last two decades has produced more than 300 quantum simulators in operation worldwide using a wide variety of experimental platforms. Recent advances in several physical architectures promise a golden age of quantum simulators ranging from highly optimized special purpose simulators to flexible programmable devices. These developments have enabled a convergence of ideas drawn from fundamental physics, computer science, and device engineering. They have strong potential to address problems of societal importance, ranging from understanding vital chemical processes, to enabling the design of new materials with enhanced performance, to solving complex computational problems. It is the position of the community, as represented by participants of the NSF workshop on "Programmable Quantum Simulators," that investment in a national quantum simulator program is a high priority in order to accelerate the progress in this field and to result in the first practical applications of quantum machines. Such a program should address two areas of emphasis: (1) support for creating quantum simulator prototypes usable by the broader scientific community, complementary to the present universal quantum computer effort in industry; and (2) support for fundamental research carried out by a blend of multi-investigator, multi-disciplinary collaborations with resources for quantum simulator software, hardware, and education.