The high-precision gravity measurements of cold atom experiments puts highly demands on the design and qualification of magneto-optical trap. We present a new modular magneto-optical trap for the cooling and manipulation of rubidium atom interferometry based on free space optical bench technology, which has been developed for a portable atomic inertial sensor. The setup consists of an integrated cooling laser injecting module, a free space bench module, an integrated Raman laser injecting module and a reflecting mirror attached to a single tri-axial accelerometer. The traditional magneto-optical trap includes 3 pairs of commercial cooling laser injecting lens, which are hard to assembled together in 3 mutually perpendicular directions and intersected at a common point. This paper introduces a new free space bench method to meet the angle and position requirements of magneto-optical trap. The vertical angle error of each pair of Cooling beams and intersection coincidence distance can be controlled in a small range. And the free space bench module is easy to control the parameters of laser beams, such as power and polarization. Theoretical analysis and experimental results show that the new modular magneto-optical trap is more reliable and robust in comparison with traditional MOT.
The high-precision gravity measurements of cold atom experiments puts highly demands on the design and qualification of magneto-optical trap. We present a new modular magneto-optical trap for the cooling and manipulation of rubidium atom interferometry based on free space optical bench technology, which has been developed for a portable atomic inertial sensor. The setup consists of an integrated cooling laser injecting module, a free space bench module, an integrated Raman laser injecting module and a reflecting mirror attached to a single tri-axial accelerometer. The traditional magneto-optical trap includes 3 pairs of commercial cooling laser injecting lens, which are hard to assembled together in 3 mutually perpendicular directions and intersected at a common point. This paper introduces a new free space bench method to meet the angle and position requirements of magneto-optical trap. The vertical angle error of each pair of Cooling beams and intersection coincidence distance can be controlled in a small range. And the free space bench module is easy to control the parameters of laser beams, such as power and polarization. Theoretical analysis and experimental results show that the new modular magneto-optical trap is more reliable and robust in comparison with traditional MOT.
Magneto-optical traps (MOTs) are a workhorse technology for neutral-atom quantum sensing, simulation, and computing. Here, we demonstrate a MOT optimized for inertial quantum sensing and precision metrology applications. Our MOT traps 4×108 cesium (Cs) atoms in a robust, modular system that achieves stable operation through two design features: (1) we use divergent cooling laser beams to reduce unwanted reflections and (2) optical elements are mounted in a fiber-coupled, compact, and modular cage rigidly attached to the vacuum chamber. Following polarization-gradient cooling (PGC), the system produces atom samples with temperatures below 10 μK, similar to those achieved in conventional MOTs that use collimated laser beams. In addition, we observe trapping of 2×107 Cs atoms in a non-conventional MOT geometry, where the cooling laser beams are diagonal to the principal axis of the quadrupole magnetic field.
In cold atom physics, the complexity of traditional magneto-optical trap system limits the use of their associated instruments for field applications in atomic physics, such as gravity mapping, space navigation and deep space exploration. This study introduces a novel compact MOT design that addresses these issues by simplifying the structure and reducing the size. The height of the unit is 0.7 m, the volume is 6.3×10−2m3 and the mass is 11.32 kg. The new design utilizes a single laser to generate the two different frequencies needed for laser cooling by internally splitting the beam, shifting the frequency and then combining them, effectively controlling both the cooling and repumping beams. The compact vacuum chamber optical path, in conjunction with the magnetic field, facilitates the capture of 87Rb atoms in an ultra-high vacuum environment. Experimental results demonstrate an atom loading rate of up to 1.79×10787Rb atoms per second, confirming the system’s effectiveness in capturing and cooling 87Rb atoms. This design provides a flexible and portable solution, offering valuable insights for the advancement of compact MOT and its applications in cold atom physics.
Magneto-optical traps (MOTs), indispensable to cold-atom-based quantum computing and quantum precision measurement, are increasingly desired in compact and stable form. Particularly, the six-beam 3D-MOT, distinguished by symmetric geometry and superior trapping performance, finds particularly broad applications. Conventional implementations, however, rely on complex and bulky free-space optics, hindering miniaturization, practical assembly, and long-term stability. Here, we demonstrate a compact six-beam 3D-MOT system that employs two multifunctional optical metasurface chips to implement the optical-field functionalities required for cooling and trapping atoms. By combining two metasurface chips and a vacuum cell, a photonic-integrated cell module (PICM) is implemented as the core assembly and the volume is only" 73*73*107 mm^3" . In success, 1.3 * 10^3 Rb atoms are trapped and cooled to the temperature of ~183 μK. It should be noticed that the laser beam is guided to the metasurface through optical fiber, thus such fully fiber-coupled architecture enables straightforward and stable operations. We believe that this work would pave a practical route toward compact and portable 3D-MOT.
We miniaturized the complex optical system responsible for the cooling, pumping, and imaging of an on-chip-based cold-atom inertial sensor. This optical bench uses bonded miniature optics and includes all the necessary optical functions. The bench has a volume of 35×25×5cm 3 . We developed a laser frequency lock adapted to the optical bench using saturated absorption in a rubidium cell. The entire laser source based on frequency doubling of 1.56 µm fiber lasers, including the control system and the saturated absorption module, fits in a 5 U rack. Using the miniaturized bench, we realized two- and three-dimensional magneto-optical traps for rubidium 87 atoms.
Atom Interferometry methods open new prospectives for absolute acceleration measurements; the quantum features of matter and the employment of atomic test masses with manipulation technique of internal and external degrees of freedom lead to a new generation of quantum sensors. In this thesis I present the development of a prototype for a transportable sensor at system and subsystem level. An instrument with such characteristics can find applications in many felds. The work has been developed in the framework of two European projects respectively oriented to the realization of an atom interferometry based absolute gravimeter for geophysical and metrological applications and to the realization of a Space Atom Interferometer for tests in micro-gravity environment. In order to focus on the possible scientific landscape I briefy illustrate in the introduction the existing devices and their characteristic performances, pointing out how the atom interferometry may represent a valid alternative leading to a new generation of quantum devices. The study, the development and the realization stages for our instrument are presented either for the laser system realization and for the the implementation of the whole apparatus. This work leads to the development of a very compact atomic physics interferometric system responding to the scientific requirements that represent our target. From the laser system side it has been realized also a complete and compact apparatus organized in a modular framework with stand alone components characterized by high working performances. This laser subsystem also includes laser sources in an external cavity configuration specially oriented to transportable apparatuses; they are characterized by an intrinsical passive stability, robustness and very narrow emission linewidth. The experience with neutral atom manipulation and with atom cooling and trapping technique has been integrated with a direct implementation, characterization and optimization of a Two Dimensional Magneto Optical Trap as a cold atoms source for an operating Atom Interferometer. Such kind of implementation represents a fundamental topic for a transportable sensor realization.
The extreme miniaturization of a cold-atom interferometer accelerometer requires the development of novel technologies and architectures for the interferometer subsystems. Here we describe several component technologies and a laser system architecture to enable a path to such miniaturization. We developed a custom, compact titanium vacuum package containing a microfabricated grating chip for a tetrahedral grating magneto-optical trap (GMOT) using a single cooling beam. In addition, we designed a multi-channel photonic-integrated-circuit-compatible laser system implemented with a single seed laser and single sideband modulators in a time-multiplexed manner, reducing the number of optical channels connected to the sensor head. In a compact sensor head containing the vacuum package, sub-Doppler cooling in the GMOT produces 15 uK temperatures, and the GMOT can operate at a 20 Hz data rate. We validated the atomic coherence with Ramsey interferometry using microwave spectroscopy, then demonstrated a light-pulse atom interferometer in a gravimeter configuration for a 10 Hz measurement data rate and T = 0 - 4.5 ms interrogation time, resulting in Δ g / g = 2.0e-6. This work represents a significant step towards deployable cold-atom inertial sensors under large amplitude motional dynamics.