Quantum gas microscopy of dipolar atoms is a promising opportunity to expand upon previous quantum simulations of neutral atoms in optical lattices. Erbium atoms interact via the long-range magnetic dipole-dipole interaction, which leads to a variety of new many-body effects and strongly correlated phases that are currently unexplored in microscopes with only short-range interactions. In this thesis I will detail progress toward the construction of an erbium quantum gas microscope as well as the techniques we implemented to produce a Bose-Einstein condensate of $8\times10^4$ atoms in under a second. These include the installation of a dual-stage magneto-optical trap, a stroboscopic optical dipole trap, as well as a tunable crossed optical dipole trap that allows for efficient evaporation of both bosonic and fermionic isotopes. I will also discuss the frequency stabilization systems we have implemented to produce laser linewidths of less than $1$ kHz for near-resonant laser cooling on narrow transitions and a custom, high NA reflective objective to be used as part of a high resolution imaging system. Finally, I will discuss the noise properties of charge-coupled devices and the photon counting techniques that are needed for having high fidelities while using fast imaging schemes.
Quantum gas microscopy of dipolar atoms is a promising opportunity to expand upon previous quantum simulations of neutral atoms in optical lattices. Erbium atoms interact via the long-range magnetic dipole-dipole interaction, which leads to a variety of new many-body effects and strongly correlated phases that are currently unexplored in microscopes with only short-range interactions. In this thesis I will detail progress toward the construction of an erbium quantum gas microscope as well as the techniques we implemented to produce a Bose-Einstein condensate of 8×104 atoms in under a second. These include the installation of a dual-stage magneto-optical trap, a stroboscopic optical dipole trap, as well as a tunable crossed optical dipole trap that allows for efficient evaporation of both bosonic and fermionic isotopes. I will also discuss the frequency stabilization systems we have implemented to produce laser linewidths of less than 1 kHz for near-resonant laser cooling on narrow transitions and a custom, high NA reflective objective to be used as part of a high resolution imaging system. Finally, I will discuss the noise properties of charge-coupled devices and the photon counting techniques that are needed for having high fidelities while using fast imaging schemes.
Quantum gas microscopy provides an exciting platform for the study of in situ atom-atom interactions. Recent advances in quantum gas microscopy have allowed the probing of the Bose-Hubbard and Fermi-Hubbard Hamiltonian with a variety of atomic species. In this thesis, we are currently extending these platforms with the introduction of an Erbium Dipolar Quantum Gas Microscope which will allow us to study dipole-dipole interactions in a lattice. Erbium has several exciting properties, which increase the control and flexibility of these systems. These include stable bosonic and fermionic isotopes, a large magnetic dipole moment (7uB), a large spin value (J=6 and F=19/2 for bosonic and fermionic isotopes), a rich Feshbach spectrum, and several useful broad and narrow atomic transitions. A broad 401 nm transition can be used for imaging, which in combination with a 266 nm lattice spacing will provide fast time scales and access to a dipole-dipole interaction of approximately 30 Hz. This thesis will document the progress toward an Erbium Quantum Gas Microscope and include a variety of systems which have been developed. It will also show the first ever 841nm, red-detuned Magneto-Optical Trap with temperatures as low as 400 nK and a phase space density up to 0.05. This, in combination with other improvements, will allow for faster cycle times and more control over the system. These developments will allow us to benefit from the long-range interaction of Erbium and probe the Extended Bose-Hubbard and Extended Fermi-Hubbard Hamiltonian to an unprecedented degree.
Quantum gas microscopy is an exciting platform for the study ofin situatom-atom interactions.Erbium, a dipolar atom, presents an opportunity to extend previous quantum gas microscopy ex-periments to more complex systems influenced by long-range, anisotropic interactions. In this the-sis, I present progress towards a quantum gas microscope of erbium atoms, including details on thedesign of a novel accordion lattice system. This system will allow us to dynamically tune the spac-ing of both the vertical and horizontal optical lattices confining the atoms. In addition, I present onthe sub-second generation of erbium Bose-Einstein condensates, made possible by implementing atwo-stage magneto-optical trap and a crossed optical dipole trap with a tunable geometry.
Long-range interactions are important to complex physical systems. Specifically in quantum mechanical many-body systems, long-range interactions promote spatial structures, give rise to quantum frustration, and generate quantum entanglement. Nevertheless, quantum simulations of lattice systems have largely not been able to realize long-range interactions. Many efforts are underway to explore long-range interacting lattice systems using polar molecules, Rydberg atoms, and magnetic atoms. In this thesis, I present the realization of long-range interacting itinerant systems using magnetic erbium atoms. I start by discussing the construction of the Erbium quantum gas microscope, including the installation of an in-vacuum high-numerical-aperture objective, various optical lattices, and potential projection through the objective. Then, I present emerging quantum phases with half-filling and directly probe the spatial structures of dipolar quantum solids using site-resolved imaging. A kaleidoscope of phases emerges as we tune the dipolar interaction, demonstrating the great tunability of this experimental platform. The dipolar interactions can be tuned slowly to study first-order quantum phase transitions between different solids. Next, I discuss topological phases that emerge with unity filling. With a zoo of Fano-Feshbach resonances, erbium atoms are gifted with the flexibility of widely tunable on-site interaction, allowing continuous probing of the quantum phase transitions between topologically trivial and non-trivial phases. We explore average symmetry protected topological phases as an instance of the mixed state quantum order. Finally, I briefly discuss the observation of spin squeezing with itinerant systems and super- and sub-radiance in a sub-wavelength optical lattice.
Ultracold atoms are powerful platforms through which to study many-body physics. In recent years there has been a marked increase in the number and variety of species (lanthanides, transition metals, dipolar molecules, etc.) brought to ultracold temperatures, providing new ingredients from which to build interesting systems. In this thesis I report on the design and construction of an erbium-lithium mixture apparatus with broad applicability for quantum simulation. The combination of large mass imbalance, competition of interaction length scales, and variable quantum statistics points toward this mixture hosting a rich variety of Bose-Bose and Bose-Fermi phases with applications ranging from condensed matter to astrophysics. Leveraging these desirable properties, however, necessitated the development of a new quantum gas platform. The first section of this thesis is dedicated to describing that process in detail. The second section of this thesis describes the development of experimental sequences through which we synthesize quantum gases. In our experiments we successively laser cool each species before combining them in a suite of optical dipole traps for evaporative cooling to degeneracy. I finally present our creation of the first degenerate Bose-Bose mixture of erbium-166 and lithium-7, as well as a measurement of the interspecies s-wave scattering length.
This thesis describes the methods used to achieve single-atom and single-site resolved fluorescence imaging of a quantum gas of fermionic atoms held in an optical lattice. This kind of quantum gas microscopy has been previously applied to bosonic atoms in two experiments, and has allowed for extensive studies of many-body quantum systems. Here we detail methods to extend the techniques of quantum gas microscopy to fermionic species of atoms, opening the door to quantum simulation of electronic models of condensed matter physics. We prepare quantum degenerate gases of fermionic 40K through sympathetic cooling with a gas of \Rb. The gas prepared is trapped less than 1 mm away from a thin vacuum window, an experimental geometry which permits interrogation with a large Numerical Aperture microscope objective. The cloud is loaded into a 527 nm-period cubic optical lattice, ideal for quantum simulation of many-body models of fermionic particles such as the Hubbard model. The optical lattice is designed to allow for potential depths up to V/kB = 250 microKelvin, sufficient to strongly confine 40K atoms into individual lattice sites. EIT cooling --- a technique previously demonstrated in ion-trapping experiments --- is used to cool the fermionic atoms deeply towards the ground motional state of the lattice wells. We collect the photons scattered during continuous application of EIT cooling, while atoms are kept pinned in the lattice for many seconds. We strongly suppress all other sources of light with the use of a modulated cooling scheme and a spinning chopper wheel. Collecting the scattered light produced during 2 s of EIT cooling allows us to resolve single atoms in a fluorescence image. We demonstrate that the high resolution of our imaging apparatus also permits atom positions to be precisely identified on the length scale of the optical lattice. Thus we demonstrate the realisation of a quantum gas microscope for fermionic atoms, allowing for precise investigation of the ground states and dynamics of correlated quantum states of fermionic particles.
This thesis details the complete upgrade and renovation of an existing experimental platform into a high-resolution quantum gas microscope for ultracold 87Rb atoms. Quantum gas microscopes enable site-resolved imaging, providing unprecedented access to quantum statistical effects and many-body phenomena. While such instruments are often employed to study physics in optical lattices, we have innovatively adapted our apparatus to investigate bulk system behavior. A major part of this project involved upgrading the scientific apparatus and retrofitting the previous system. We introduced new optical components, including a high-NA objective, and improved the vacuum system for better optical access. Extensive lab renovations, from upgrading the optical table to reorganizing the laser and imaging setups, were carried out to enhance mechanical and thermal stability. Rigorous optical benchmarking confirmed that the objective achieves diffractionlimited imaging, which is critical for resolving single atoms. This capability allowed us to detect density fluctuations at the scale of the thermal de Broglie wavelength in a quasi-two-dimensional gas of 87Rb atoms. In an experiment resembling Hanbury Brown and Twiss interferometry, we measured a 30% enhancement in the second-order correlation function in situ, demonstrating strong bosonic bunching. This outcome underscores the microscope’s precision and the importance of high-resolution imaging in capturing subtle quantum statistical effects. The successful realization of this apparatus demonstrates the utility of quantum gas microscopes in probing bulk systems. With this new platform in place, future studies can explore critical phenomena, many-body correlations, matter-wave emission, and quantum simulations with cold atoms.