Demonstration of an integrated nanophotonic chip-scale alkali vapor magnetometer using inverse design

Abstract

Recently, there has been growing interest in the miniaturization and integration of atomic-based quantum technologies. In addition to the obvious advantages brought by such integration in facilitating mass production, reducing the footprint, and reducing the cost, the flexibility offered by on-chip integration enables the development of new concepts and capabilities. In particular, recent advanced techniques based on computer-assisted optimization algorithms enable the development of newly engineered photonic structures with unconventional functionalities. Taking this concept further, we hereby demonstrate the design, fabrication, and experimental characterization of an integrated nanophotonic-atomic chip magnetometer based on alkali vapor with a micrometer-scale spatial resolution and a magnetic sensitivity of 700 pT/√Hz. The presented platform paves the way for future applications using integrated photonic–atomic chips, including high-spatial-resolution magnetometry, near-field vectorial imaging, magnetically induced switching, and optical isolation.

Laser-written vapor cells for chip-scale atomic sensing and spectroscopy

“…We have demonstrated proof-of-principle applications of a laser-written vapor-cell (LWVC) for sub-Doppler saturated absorption spectroscopy of rubidium and single beam optical magnetometry based on paramagnetic Faraday rotation. The introduced laser-writing technique provides a suitable interaction volume for precision atomic spectroscopy and atomic quantum sensing with 3D structuring versatility and it has high potential for integration with waveguide-based photonic structures [62,67,68] and optical components [9,10] as well as with optical fibers for chipscale [29] and fiber-coupled [79] atomic sensors. As further development, different geometries and filling techniques based on alkali metal azide [80], mixture of argon and nitrogen [70] as well as other noble gas species like 3 He and 129 Xe [81], will be implemented to optimize specific applications as atomic references, atomic clocks, optical magnetometers and atomic gyroscopes.…”

“…typically set by the transverse beam width, is desirable for Doppler-free applications [29], like atomic frequency references [61] and atomic clocks [62,63], as well as for high-sensitivity spin-based atomic sensors like optical magnetometers [64,65] and atomic gyroscopes [66]. The combination of the latter goal with integrated photonics led to state-of-the-art photonic-atomic chips, which make use of hybrid schemes where a separate mm or 𝜇m-sized microfabricated vapor cell is deposited on the top of the photonic chip [67,68]. Then, complex extreme mode-converting apodized grating structure or a nanophotonic spin selector are used to couple light between atomic microcell and photonic waveguides, respectively [67,68], with relatively low efficiency.…”

“…The combination of the latter goal with integrated photonics led to state-of-the-art photonic-atomic chips, which make use of hybrid schemes where a separate mm or 𝜇m-sized microfabricated vapor cell is deposited on the top of the photonic chip [67,68]. Then, complex extreme mode-converting apodized grating structure or a nanophotonic spin selector are used to couple light between atomic microcell and photonic waveguides, respectively [67,68], with relatively low efficiency.…”

Measurement of DC and AC electric fields inside an atomic vapor cell with wall-integrated electrodes

“…We have found that the integration of highly conductive doped-Si parts into borosilicate glass walls via an anodicbonding technique [23][24][25][26] enables the fabrication of highand ultra-high-vacuum devices. The Si electrodes afford electric-field control inside the cell directly through the cell wall.…”

Collimated versatile atomic beam source with alkali dispensers

“…Alkali atoms are a key resource for numerous emerging chip-scale quantum technologies 1,2 . With the ease of batch fabrication methods, chip-based atomic devices such as vapor cell atomic clocks and magnetometers [3][4][5][6] , quantum gravimeter 7 , and Bose-Einstein condensates on chip [8][9][10][11] have become increasingly attractive for realizing novel quantum device architectures that can be more widely disseminated. As this miniaturization trend continues, there is a growing need to integrate small-scale alkali atom sources directly on chip or within a small volume vacuum cell.…”