We report on an ion-optical system that serves as a microscope for ultracold ground state and Rydberg atoms. The system is designed to achieve a magnification of up to 1000 and a spatial resolution in the 100 nm range, thereby surpassing many standard imaging techniques for cold atoms. The microscope consists of four electrostatic lenses and a microchannel plate in conjunction with a delay line detector in order to achieve single particle sensitivity with high temporal and spatial resolution. We describe the design process of the microscope including ion-optical simulations of the imaging system and characterize aberrations and the resolution limit. Furthermore, we present the experimental realization of the microscope in a cold atom setup and investigate its performance by patterned ionization with a structure size down to 2.7 μ m. The microscope meets the requirements for studying various many-body effects, ranging from correlations in cold quantum gases up to Rydberg molecule formation.
We report on an ion-optical system that serves as a microscope for ultracold ground state and Rydberg atoms. The system is designed to achieve a magnification of up to 1000 and a spatial resolution in the 100 nm range, thereby surpassing many standard imaging techniques for cold atoms. The microscope consists of four electrostatic lenses and a microchannel plate in conjunction with a delay line detector in order to achieve single particle sensitivity with high temporal and spatial resolution. We describe the design process of the microscope including ion-optical simulations of the imaging system and characterize aberrations and the resolution limit. Furthermore, we present the experimental realization of the microscope in a cold atom setup and investigate its performance by patterned ionization with a structure size down to 2.7 μ m. The microscope meets the requirements for studying various many-body effects, ranging from correlations in cold quantum gases up to Rydberg molecule formation.
Quantum Gases
Quantum microscopes have been used for more than a decade now to image the many-body states of quantum gases in optical lattices. However, their resolution is limited to optical wavelengths, and they can typically image only a single layer of atoms. As a complementary technique for imaging quantum gases, Veit et al. developed an ion microscope. Atoms were first ionized by laser light, and the resulting ions were controlled using electrostatic lenses and imaged. Although the technique was demonstrated on rubidium atoms in their ground state, it is expected that it will also work on highly excited Rydberg atoms and will enable three-dimensional and time-dependent imaging.
Phys. Rev. X 11 , 011036 (2021).
In cold atom experiments, high resolution imaging systems have been used to extract in-situ density information when studying quantum gases, which is one of the hot topics in this field. Such a system is usually called “quantum-gas microscope”. In order to achieve a long working distance and large magnification, high resolution imaging of cold atoms through a vacuum window usually requires a long distance between the atoms and the camera. However, due to space limitation caused by a large number of nearby optical elements, it may be difficult to realize a long imaging system, which is a common case in cold atom experiments. Herein we present an imaging system that can achieve a short distance between the atoms and the image plane with diffraction-limited 1 μm resolution and 50 magnification. The telephoto lens design is adopted to reduce the back focal length and enhance the pointing stability of the imaging lens. The system is optimized at an operating wavelength of 767 nm and corrects aberrations induced by a 5-mm-thick silica vacuum window. At a working distance of 32 mm, a diffraction-limited field of view of 408 μm is obtained. The simulation result shows that by changing the air space between lenses, our design operates across a wide range of window thicknesses (0–15 mm), which makes it robust enough to be used in typical laboratories. This compact imaging system is made from commercial on-shelf Φ2 in (1 in = 2.54 cm) singlets and consists of two components: a microscope objective with a numerical aperture of 0.47 and a telephoto objective with a long effective focal length of 1826 mm. Both are infinitely corrected, allowing the distance between them to be adjusted to insert optical elements for irradiating atoms with laser beams of different wavelengths without affecting the imaging resolution. Taking the manufacturing and assembling tolerances into consideration, the Monte Carlo analyses show that more than 95% of the random samples are diffraction-limited within the field of view. This high success rate ensures that these two objectives can be achieved easily in the experiment. Combined with its performance with other wavelengths (470–1064 nm), this imaging system can be used for imaging different atom species, such as sodium, lithium, and cesium.
The advent of the quantum gas microscope allowed for the in situ probing of ultracold gaseous matter on an unprecedented level of spatial resolution.However, the study of phenomena on ever smaller length scales, as well as the probing of three-dimensional systems, is fundamentally limited by the wavelength of the imaging light for all techniques based on linear optics.Here, we report on a high-resolution ion microscope as a versatile and powerful experimental tool to investigate quantum gases.The instrument clearly resolves atoms in an optical lattice with a spacing of 532 nm over a field of view of 50 sites and offers an extremely large depth of field on the order of at least 70 μm.With a simple model, we extract an upper limit for the achievable resolution of approximately 200 nm from our data.We demonstrate a pulsed operation mode enabling 3D imaging and allowing for the study of ionic impurities and Rydberg physics.
In this work we describe the design and implementation of an optical system that enables the study of the interactions of Rydberg atoms or other Rydberg species in well-defined geometries. To understand and observe the dynamics of Rydberg interactions, the ability to engineer different arrangements of microscopic cold atom traps and manipulate their positions with a precision of a few microns is essential. This is accomplished by a custom designed high-numerical-aperture long-working-distance objective lens and a spatial light modulator device to control the phase of an incoming optical beam. Several different trap geometries have been realized, with a spatial resolution of a few microns, including a 1-dimensional chain, a 2-dimensional square grid, and a circular array of traps. The objective lens has been designed to provide diffraction limited performance at multiple wavelengths facilitating the creation of not only micron-scale atom traps but also the fluorescence imaging of trapped atoms. The system enables precise control over trap positions, and hence the locations at which atoms might be excited, with applications in, for example, the study of long-range interactions between Rydberg atoms, the creation of long-range Rydberg molecules, the implementation of qubits for quantum computing based on Rydberg atoms, and in quantum simulation.
We present a high-resolution, simple, and versatile system for imaging ultracold Rydberg atoms in optical lattices. The imaging objective is a single aspheric lens [with a working distance of 20.6 mm and a numerical aperture (NA) of 0.51] placed inside the vacuum chamber. Adopting a large-working-distance lens leaves room for electrodes and electrostatic shields to control electric fields around Rydberg atoms. With this setup, we achieve a Rayleigh resolution of 1.10 μm or 1.41λ (λ = 780 nm), limited by the NA of the aspheric lens. For systems of highly excited Rydberg states with blockade radii greater than a few μm, the resolution achieved is sufficient for studying many physical processes of interest.
In this thesis, we describe the implementation of a cavity-microscope system for cold atoms experiments. This technology combines a high-finesse optical resonator and a high-resolution imaging system. Stability and alignment are crucial aspects of the setup. A cavity holder has been specifically designed to answer the mechanical demands of the cavity-microscope, ensuring its stability. Furthermore, an assembly and alignment procedure has been carefully planned to bring together the bare optical and mechanical components which form the apparatus. We concretely show the efficacy of the defined technique by constructing an updated setup for the Microscope Experiment in the Laboratory for Quantum Gases. The device has been adapted to address the specifics of the experiment with careful attention to the features needed for its long-term goal. Finally, we demonstrate that the implemented procedure maintains intact the optical properties of the system and that it meets the mechanical requirements discussed above. These tests validate the reliability and the integrity of the devised technique. Through the implemented device, two main benefits emerge. Firstly, it enables the detection of atom numbers in a continuous and high-resolved way, two features that are typically challenging to be incorporated together. Secondly, it provides a method to spatially and temporally control the atom-cavity coupling, which is collective in standard cavity QED setups. Ultimately, this technology opens up stimulating prospects for controlled simulations of long-range interacting physical systems.