On-chip integrated non-magnetic heating devices for quantum sensing applications

Recent years have seen rapid development of chip-scale atomic devices due to their great potential in the field of high-resolution biomedical imaging. However, devices of this kind rely heavily on non-magnetic heating approaches for the temperature control of alkali vapor cell. Conventional methods namely flexible printed circuits (FPC) films present significant drawbacks including large alignment errors and integration difficulties, thereby diminishing their performance in miniaturized atomic devices. In this study, a CMOS-compatible non-magnetic heating chip is developed with double layer heating circuit directly fabricated on glass wafer, and 400 nm gap (between layers) is achieved to ensure maximized magnetic field cancellation. The devices is designed through genetic algorithm (GA) and is finally lay out on 4 × 4 mm² sized glass wafer, which enabled further integration as the wall of micro fabricated alkali vapor cell. Experimental results show that our design is advantageous in magnetic field suppression with residual magnetic flux density of only 1.299 nT/mA and 4.469 nT/mA at the aligned errors of 2μm and 30μm, respectively. The magnetic flux density introduced by the current in the z-direction is minimized to 5.528 nT/mA. In addition, due to high alignment precision of CMOS-compatible nano fabrication ( 10 nm compared with 30 um of FPC fabrication), our method further enables high-spatial-resolution magnetic field cancellation or generation for chip-scale atomic devices. Our work demonstrates the effectiveness of GA calculation combined with nano fabrication technology in pushing the limit of non-magnetic heating and chip-scale integration for future miniaturized atomic devices, which holds great importance in Magnetoencephalography (MEG) and Magnetocardiogram (MCG).