Traditional magneto-optical traps are often bulky and complex, which limits their application in portable and scalable technologies. In this study, we propose a method for generating cold atoms using a transmission-grating-based magneto-optical trap (TGMOT). This approach addresses the limitations of traditional magneto-optical traps using a transmission-grating design that simplifies the optical configuration, allowing for efficient atom capture with a single incident beam. Our theoretical model demonstrates that the TGMOT maintains balanced forces on the trapped atoms, thereby enhancing cooling and capture efficiency compared to existing grating-based systems. Experimental results indicate that the TGMOT has a high atom-capture rate and capacity. The proposed TGMOT scheme represents a promising avenue for developing miniaturized portable quantum sensing devices, atomic clocks, and other compact quantum technologies.
Traditional magneto-optical traps are often bulky and complex, which limits their application in portable and scalable technologies. In this study, we propose a method for generating cold atoms using a transmission-grating-based magneto-optical trap (TGMOT). This approach addresses the limitations of traditional magneto-optical traps using a transmission-grating design that simplifies the optical configuration, allowing for efficient atom capture with a single incident beam. Our theoretical model demonstrates that the TGMOT maintains balanced forces on the trapped atoms, thereby enhancing cooling and capture efficiency compared to existing grating-based systems. Experimental results indicate that the TGMOT has a high atom-capture rate and capacity. The proposed TGMOT scheme represents a promising avenue for developing miniaturized portable quantum sensing devices, atomic clocks, and other compact quantum technologies.
Cold atoms produced in magneto-optical traps (MOTs) have underpinned advances in emerging quantum technologies, including quantum computing, precision metrology, and fundamental physics. Grating-based MOT (gMOT), which employs a reflective diffraction grating to enable laser cooling from a single incident beam, offers a compact alternative to conventional six-beam MOTs. However, the inherent asymmetry of gMOT beam geometry can compromise the trapping stability and efficiency, particularly for atomic species with complex internal level structures. Here, we present a geometric-phase dielectric metasurface that simultaneously engineers the transmitted and diffracted wavefronts with desired polarization states, enabling full MOT operation under axial illumination using a single planar optical element. This metasurface-based architecture restores the symmetry in the trapping forces while preserving the compactness and simplicity of gMOTs. Using this approach, we demonstrate the trapping and cooling of cesium─an atomic species widely regarded as challenging for standard gMOT implementations─and analyze the trapping mechanism through numerical calculations. By providing independent control over key trapping parameters within a planar and alignment-simplified platform, this work establishes a route toward compact, robust, and species-flexible cold-atom systems, thereby expanding the applicability of miniaturized MOTs for integrated quantum technologies.
Compared with the conventional three-dimensional magneto-optical trap (3D MOT), the grating magneto-optical trap (GMOT) enables the cooling and trapping of atoms with only a single beam of light, thereby significantly reducing the overall volume of the device. Here, a grating chip with high diffraction efficiency is designed, and its parameters are optimized through simulations, which effectively suppresses the power of the zero-order diffracted light. Subsequently, the grating chip is fabricated and characterized, and using this chip, we successfully trap 1.7×106 atoms. The temperatures of the atomic cloud in the axial and radial directions are 5.6 mK and 17.0 mK, respectively. The successful implementation of the atom cooling and trapping experiment based on the diffraction grating provides important reference for the miniaturization of cold atom-based quantum sensors.
Abstract Laser-cooled atoms are a key technology for many calibration-free measurement platforms—including clocks, gyroscopes, and gravimeters—and are a promising system for quantum networking and quantum computing. The optics and vacuum hardware required to prepare these gases are often bulky and not amenable to large-volume manufacturing, limiting the practical realization of devices benefiting from the properties of cold atoms. Planar, lithographically produced optics including photonic integrated circuits, optical metasurfaces (MSs), and gratings offer a pathway to develop chip-scale, manufacturable devices utilizing cold atoms. As a demonstration of this technology, we have realized laser cooling of atomic Rb in a grating-type magneto-optical trap (MOT) using planar optics for beam launching, beam shaping, and polarization control. Efficient use of available light is accomplished using MS-enabled beam shaping, and the performance of the planar optics MOT is competitive with Gaussian-beam illuminated grating MOTs.
We demonstrate for the first time the two-color cooling and trapping of alkaline-earth atoms in a grating magneto-optical trap (gMOT). The trap is formed by a single incident laser beam together with four secondary beams that are generated via diffraction from a nanostructured wafer. A grating structure for a gMOT operating with strontium atoms is optimized and fabricated. We trap 10688Sr atoms on the 1S0→1P1 transition at 461nm and transfer 25% of these atoms to the second cooling stage on the narrower 1S0→3P1 intercombination transition at 689nm, preparing a sample of 2.5×105 atoms at 5μK. These results demonstrate for the first time the applicability of the gMOT technology in conjunction with two widely differing wavelengths and enable the continued miniaturization of alkaline-earth based quantum technologies like optical atomic clocks.
Bose-Einstein condensates (BECs) have been proposed for many applications in atom interferometry, as their coherence over long evolution times promises unprecedented sensitivity. To date, BECs can be efficiently created in devices using atom chips, but these are still complex and place high demands on size, weight and power. To further simplify these setups, we equipped an atom chip with a nano-structured diffraction-grating to derive all beams for the magneto-optical trap (MOT) from a single laser beam. Moreover, using a 2D+-MOT as an atomic source and a beam with uniform intensity for the grating illumination, we capture 1×109 atoms in one second, cool them to 14μK, and demonstrate magnetic trapping using the atom chip. This is a major step towards the simplification of portable BEC devices for quantum sensing on earth and in space.
Magneto-optical traps are central to atomic and molecular quantum technologies and precision tests of fundamental physics, where both sensitivity and bandwidth scale strongly with atom number and loading rate. We demonstrate that employing multiple, closely spaced optical frequency components in the cooling light of a 87Rb magneto-optical trap -- without utilizing any additional slowing techniques -- can double the steady state atom number and increase the loading rate by up to a factor of 4, compared to a conventional single-frequency implementation. Subsequently, we capture up to 1.0(1)×1010 atoms with a loading rate of up to 1.3(2)×1011atomss−1 from a thermal background. Numerical simulations reproduce the observed trends and predict substantially larger gains for increased trap sizes beyond our experimental bounds. By re-examining earlier studies of multi-frequency atom capture in the context of modern experimental hardware and emerging applications, we show that previously identified limitations can be avoided and establish multi-frequency cooling as a practical and scalable route to high-flux cold-atom sources. These results have immediate applications in portable atom-based quantum sensing, where higher bandwidth and precision can be achieved without forgoing compactness, and in atom-interferometric tests of fundamental physics, which benefit from access to larger-mass quantum systems.