Abstract An atomics package is the heart of any atom based quantum sensing device. Here we report on the realisation of a field deployable atomics package for alkaline earth atoms, e.g. Sr or Yb. In terms of size (∼121 L), weight (<75 kg) and power (∼320 W), it is the smallest package to date which is designed to load Sr atoms into an optical lattice. It consists of an ultra-high vacuum assembly (<4 L), lasers, magnetic field coils & optics required for cooling & trapping as well as a module for imaging & detection. The package can routinely produce ultra cold and dense samples of 1.6 × 105 88Sr atoms trapped in a 1D optical lattice in less than a second. Its robustness has been demonstrated by conducting two transportation campaigns within out-of-the-lab environments. This advancement will have impact not only on transportable optical clock development but also will influence the wider areas of quantum science and technologies, particularly requiring field deployable cold atom based quantum sensors.
Abstract An atomics package is the heart of any atom based quantum sensing device. Here we report on the realisation of a field deployable atomics package for alkaline earth atoms, e.g. Sr or Yb. In terms of size (∼121 L), weight (<75 kg) and power (∼320 W), it is the smallest package to date which is designed to load Sr atoms into an optical lattice. It consists of an ultra-high vacuum assembly (<4 L), lasers, magnetic field coils & optics required for cooling & trapping as well as a module for imaging & detection. The package can routinely produce ultra cold and dense samples of 1.6 × 105 88Sr atoms trapped in a 1D optical lattice in less than a second. Its robustness has been demonstrated by conducting two transportation campaigns within out-of-the-lab environments. This advancement will have impact not only on transportable optical clock development but also will influence the wider areas of quantum science and technologies, particularly requiring field deployable cold atom based quantum sensors.
Atomic clocks are crucial for precise time dissemination, supporting industrial applications for navigation, telecommunication, the financial system, and the energy industry by ensuring accurate timekeeping and synchronization. At present, the best atomic clocks are based on optical transitions. Optical lattice clocks based on Yb or Sr achieve fractional frequency uncertainties in the low 10^(-18) regime. This remarkable accuracy allows resolving the gravitational redshift on the centimeter scale. This progress has driven the development of compact transportable optical lattice clocks, which are crucial for field- or even space applications. Especially for space operation, there is a critical need to minimize size, weight and power consumption of key components, particularly the source of laser-cooled atoms. Conventional atom sources for optical lattice clocks consist of an atomic oven with a high power consumption and a six-beam magneto-optical trap (MOT) that requires a large and complex optical setup. This thesis addresses the technical challenges associated with the development of compact sources of laser-cooled alkaline-earth-like atoms by demonstrating a miniaturized atomic oven and a miniaturized MOT for Yb and Sr. The MOT generation is tested with three types of in-vacuum optical elements that generate all the required laser beams for three-dimensional trapping and cooling with only one single input beam. A quasi-monolithic aluminum structure generating a conventional MOT beam geometry that is called pyramid reflector is compared to a quasi-planar optical element called Fresnel reflector. Both are characterized and compared using the same high-flux Yb source. Particularly, two-stage cooling of a fermionic alkaline-earth-like atom in a non-conventional MOT configuration is performed for the first time, demonstrating the applicability of planar MOT optics in optical lattice clocks. Furthermore, a planar diffraction grating is combined with the miniaturized atomic oven inside a highly compact vacuum chamber. The atomic oven is based on a circular fused silica chip and is tested by loading an Yb MOT generated with the pyramid reflector and a Sr MOT generated with the diffraction grating. It requires less than 250 mW of electrical heating power to generate a MOT loading rate above 10^8 atoms/s with the pyramid reflector. The presented components form a compact source of laser-cooled Yb or Sr atoms, and, when combined with a compact optical lattice setup, will serve as the basic building blocks of a future transportable optical lattice clock.
Atomic clocks are crucial for precise time dissemination, supporting industrial applications for navigation, telecommunication, the financial system, and the energy industry by ensuring accurate timekeeping and synchronization. At present, the best atomic clocks are based on optical transitions. Optical lattice clocks based on Yb or Sr achieve fractional frequency uncertainties in the low 10^−18 regime. This remarkable accuracy allows resolving the gravitational redshift on the centimeter scale. This progress has driven the development of compact transportable optical lattice clocks, which are crucial for field- or even space applications. Especially for space operation, there is a critical need to minimize size, weight and power consumption of key components, particularly the source of laser-cooled atoms. Conventional atom sources for optical lattice clocks consist of an atomic oven with a high power consumption and a six-beam magneto-optical trap (MOT) that requires a large and complex optical setup. This thesis addresses the technical challenges associated with the development of compact sources of laser-cooled alkaline-earth-like atoms by demonstrating a miniaturized atomic oven and a miniaturized MOT for Yb and Sr. The MOT generation is tested with three types of in-vacuum optical elements that generate all the required laser beams for three-dimensional trapping and cooling with only one single input beam. A quasi-monolithic aluminum structure generating a conventional MOT beam geometry that is called pyramid reflector is compared to a quasi-planar optical element called Fresnel reflector. Both are characterized and compared using the same high-flux Yb source. Particularly, two-stage cooling of a fermionic alkaline-earth-like atom in a non-conventional MOT configuration is performed for the first time, demonstrating the applicability of planar MOT optics in optical lattice clocks. Furthermore, a planar diffraction grating is combined with the miniaturized atomic oven inside a highly compact vacuum chamber. The atomic oven is based on a circular fused silica chip and is tested by loading an Yb MOT generated with the pyramid reflector and a Sr MOT generated with the diffraction grating. It requires less than 250 mW of electrical heating power to generate a MOT loading rate above 10^8 atoms/s with the pyramid reflector. The presented components form a compact source of laser-cooled Yb or Sr atoms, and, when combined with a compact optical lattice setup, will serve as the basic building blocks of a future transportable optical lattice clock.
Quantum sensors, like optical lattice clocks, undergo a continuous development from lab-based towards mobile systems. A key aspect in the miniaturization of the experimental setups is the development of compact atom sources. Conventional atom sources for alkaline-earth-like elements consist of a high-power oven and a six-beam magneto-optical trap (MOT) inside of vacuum chamber with extensive flanges, viewports and electrical feedthroughs. Here we present a highly compact vacuum package utilizing key technologies for future quantum sensor systems: A chip-based low-power atomic oven, a planar grating MOT chip, and a miniaturized vacuum pump all held inside an additively manufactured titanium vacuum chamber, featuring custom-sized vacuum flanges. In this miniaturized setup, spanning a volume of only 750 ml, we trap up to 105 Sr atoms in a MOT, requiring an oven heating power below 1 W.
Optical lattice clocks based on ytterbium (Yb) and strontium (Sr) are emerging as key technologies in precision timekeeping and metrology. Recent advancements in miniaturization and transportability are making them increasingly accessible for applications outside traditional laboratory settings. However, the degree of miniaturization is limited by the atomic source that is used to provide laser-cooled atoms for the clock spectroscopy. Conventional atomic sources for optical lattice clocks consist of a high-power oven and a magneto-optical trap (MOT) that requires six incident laser beams for three-dimensional trapping and cooling. Here, we present technologies that allow a significant miniaturization of the required experimental setups to realize a MOT for Yb and Sr. These are a chip-based microstructured atomic oven and in-vacuum optical elements that require only a single incident laser beam to generate all of the required beams for three-dimensional trapping and cooling. The oven was manufactured with LIDE® (laser induced deep etching). It was paired with an aluminum pyramid reflector to load Yb atoms into a MOT. The oven was placed directly at the outside of the reflector, forming a compact setup that is used for atom evaporation and direct trapping and cooling. In this configuration, MOT loading rates above 10^8 atoms/s were measured for oven heating powers below 250 mW. Furthermore, the microstructured oven was paired with a grating MOT chip inside a highly compact vacuum chamber. The chamber was additively manufactured from titanium and the assembled setup spans a volume of less than 750 ml. In this setup, up to 10^5 Sr atoms were trapped in the MOT.
Abstract We realize a two-stage, hexagonal pyramid magneto-optical trap (MOT) with strontium, and demonstrate loading of cold atoms into cavity-enhanced 1D and 2D optical lattice traps, all within a single compact assembly of in-vacuum optics. We show that the device is suitable for high-performance quantum technologies, focusing especially on its intended application as a strontium optical lattice clock. We prepare 2 × 10 4 spin-polarized atoms of 87 Sr in the optical lattice within 500 ms; we observe a vacuum-limited lifetime of atoms in the lattice of 27 s; and we measure a background DC electric field of 12 V m −1 from stray charges, corresponding to a fractional frequency shift of (−1.2 ± 0.8) × 10 −18 to the strontium clock transition. When used in combination with careful management of the blackbody radiation environment, the device shows potential as a platform for realizing a compact, robust, transportable optical lattice clock with systematic uncertainty at the 10 −18 level.
Optical atomic clocks provide exceptionally accurate and precise signals for timekeeping and precision measurements, but they require high-power, free-space laser configurations that limit scalability. We introduce and explore a scalable infrastructure for strontium (Sr) optical-lattice clocks that incorporates co-design of atomic-beam slowing and a magneto-optical trap (MOT) from an effusion source, generation of complex, three-dimensional free-space laser configurations with a photonic integrated circuit (PIC) and metasurface (MS) optics, and laser stabilization to a frequency-comb supercontinuum generated with integrated nonlinear photonics. With these elements, we realize MOTs of all stable strontium isotopes (84Sr, 86Sr, 87Sr, 88Sr) with populations commensurate with natural abundances, demonstrating precise beam control and robustness. Access to laser-cooled alkaline-earth atoms with scalable integrated photonics enables system engineering for optical clocks, quantum sensing, and quantum information, and our experiments demonstrate extensible technologies that advance toward a Sr optical clock largely free of bulk optics.