The microfabrication of cesium vapor cells for optically pumped magnetometry relies on optimisation of buffer gas pressure in order to maximise atomic coherence time and sensitivity to external magnetic signals. We demonstrate post-bond nitrogen buffer gas pressure tuning through localized heating of an integrated micro-pill dispenser. We characterize the variation in the intrinsic longitudinal relaxation rate, $\gamma_{10}$, and magnetic sensitivity, as a function of the resulting nitrogen buffer gas pressure. Measurements are conducted through employing an optically pumped magnetometer operating in a free-induction-decay configuration. $\gamma_{10}$ is extracted across a range of nitrogen pressures between $\sim$60-700Torr, measuring a minimum of 140Hz at 115Torr. Additionally, we achieve sensitivities as low as 130fT/$\sqrt{\text{Hz}}$ at a bias field amplitude of $\sim 50${\mu}$T. With the optimal nitrogen buffer gas pressure now quantified and achievable post-fabrication, these mass-producible cells can be tailored to suit a variety of sensing applications, ensuring peak magnetometer performance.

We present a novel approach of interfacing photonic integrated circuits with wafer-bonded MEMS vapour cells leveraging the silicon fabrication techniques for size, weight, power and cost reduction of miniature atomic systems.

The design, fabrication and characterisation of a silicon nitride optical phased array (OPA) for waveguide integration with flip-chip bonded rubidium (Rb) atomic MEMS vapour cells are demonstrated. A one-dimensional OPA with a symmetric splitter tree design at 780 nm wavelength is fabricated by electron-beam lithography and plasma dry-etching. The waveguides were cladded with silicon dioxide before bonding to an Rb MEMS vapour cell. The characterisation was performed by end-fire coupling a 780.24 nm laser to the waveguide by a lens fibre. A saturated absorption spectroscopy measurement revealed the ~ 6 MHz hyperfine transition absorption dips that can be utilised for laser frequency stabilisation for atomic cooling.

The microfabrication of cesium vapor cells for optically pumped magnetometry relies on optimization of buffer gas pressure in order to maximize atomic coherence time and sensitivity to external magnetic signals. We demonstrate post-bond nitrogen buffer gas pressure tuning through localized heating of an integrated micropill dispenser. We characterize the variation in the intrinsic longitudinal relaxation rate, gamma 10, and magnetic sensitivity, as a function of the resulting nitrogen buffer gas pressure. Measurements are conducted by employing an optically pumped magnetometer operating in a free-induction-decay configuration. gamma 10 is extracted across a range of nitrogen pressures between 60 and 700 torr, measuring a minimum of 140 Hz at 115 torr. In addition, we achieve sensitivities as low as 130 fT/root Hz at a bias field amplitude of about 50 mu T. With the optimal nitrogen buffer gas pressure now quantified and achievable post-fabrication, these mass-producible cells can be tailored to suit a variety of sensing applications, ensuring peak magnetometer performance.

We demonstrate a controllable depletion of the nitrogen buffer gas pressure in a micro-machined cesium (Cs) vapor cell from the dynamic heating of an alkali dispenser pill. When the alkali source is laser activated, the gettering compounds within the alkali pill dispenser reduce the nitrogen (N-2) content from the vapor for fine-tuning of the alkali to buffer gas pressure ratio, with a demonstrated pressure step size as low as 1 Torr. Additionally, we decrease the buffer gas pressure below 100 mTorr to evaluate the presence of other potential broadening mechanisms. Real-time control of the gas pressure ratio in the vapor cell will have notable benefits for refining atomic sensor performance and provide a routine to achieve various target pressures across a wafer bonded with a uniform back-filled buffer gas pressure.

We demonstrate a tunable, chip-scale wavelength reference to greatly reduce the complexity and volume of cold-atom sensors. A 1-mm optical path length microfabricated cell provides an atomic wavelength reference, with dynamic frequency control enabled by Zeeman-shifting the atomic transition through the magnetic field generated by the printed-circuit-board coils. The dynamic range of the laser frequency stabilization system is evaluated and used in conjunction with an improved generation of chip-scale coldatom platforms that traps 4 million 87Rb atoms. The scalability and component consolidation provide a key step forward in the miniaturization of cold-atom sensors.

We present the development of a silicon-nitride photonic integrated circuit platform aimed at a range of miniature atomic systems including atomic clocks and cold atom sensors which includes narrow-linewidth (≤3.7 kHz) distributed feedback lasers and wafer-bonded MEMS rubidium vapour cells.

Using a simple and cost-effective water-jet process, we have overcome silicon etch depth limitations to realize a 6 mm deep atomic vapor cell. We have successfully used this approach to demonstrate a two-chamber geometry by including a 25 mm meandering channel between the alkali pill chamber and main interrogation chamber. Additionally, we have recently used this approach in the fabrication of deep cut silicon cells for cold atom systems. The results will be highlighted, as well as providing an overview of our advancements on mass producible components for cold-atom systems and the amalgamation of this technology towards a fully integrated system.

We demonstrate the integration of micro-electro-mechanical-systems (MEMS) scanning mirrors as active elements for the local optical pumping of ultra-cold atoms in a magneto-optical trap. A pair of MEMS mirrors steer a focused resonant beam through a cloud of trapped atoms shelved in the F = 1 ground-state of 87Rb for spatially selective fluorescence of the atom cloud. Two-dimensional control is demonstrated by forming geometrical patterns along the imaging axis of the cold atom ensemble. Such control of the atomic ensemble with a microfabricated mirror pair could find applications in single atom selection, local optical pumping, and arbitrary cloud shaping. This approach has significant potential for miniaturization and in creating portable control systems for quantum optic experiments.

A fully integrated and mass producible platform for laser cooling has the potential to revolutionize the growing field of quantum technologies and atomic sensors. Recent advancements in the micro-fabrication of components at the heart of cold atom systems have laid the foundations for the amalgamation of a simple, stackable solution to laser cooling. In this talk we will highlight our recent progress towards a fully chip-scale, cold-atom platform, outlining our approach for on-chip wavelength referencing, examining a solution for imaging atoms in a planar stacked device, and finally discussing the limitations to passively pumped vacuum longevity.

We demonstrate a tuneable, chip-scale wavelength reference to greatly reduce the complexity and volume of cold-atom sensors. A 1 mm optical path length micro-fabricated cell provides an atomic wavelength reference, with dynamic frequency control enabled by Zeeman shifting the atomic transition through the magnetic field generated by the printed circuit board (PCB) coils. The dynamic range of the laser frequency stabilization system is evaluated and used in conjunction with an improved generation of chip-scale cold atom platforms that traps 4 million 87Rb atoms. The scalability and component consolidation provide a key step forward in the miniaturization of cold atom sensors.

Using a simple and cost-effective water jet process, silicon etch depth limitations are overcome to realize a $6\,$mm deep atomic vapor cell. While the minimum silicon feature size was limited to a $1.5\,$mm width in these first generation vapor cells, we successfully demonstrate a two-chamber geometry by including a $\sim$25~mm meandering channel between the alkali pill chamber and main interrogation chamber. We evaluate the impact of the channel conductance on the introduction of alkali vapor density during the pill activation process, and mitigate glass damage and pill contamination near the main chamber. Finally, we highlight the improved signal achievable in the $6\,$mm silicon cell compared to standard $2\,$mm path length silicon vapor cells.

A low-cost, mass-producible laser-cooling platform would have a transformative effect in the burgeoning field of quantum technologies and the wider research of atomic sensors. Recent advancements in the micro-fabrication of diffractive optics and vacuum apparatus have paved the way for a simple, stackable solution to the laser cooling of alkali atoms. In this paper we will highlight our recent investigations into a chip-scale, cold-atom platform, outlining our approach for on-chip wavelength referencing, examining a solution for imaging atoms in a planar stacked device, and finally discussing the limitations to passively pumped vacuum longevity. These results will be discussed in the context of an outlined road-map for the production and commercialisation of chip-scale, cold-atom sensors.