In recent years, sensors based on hot atomic vapor cells have emerged as a compact and highly sensitive means of measuring magnetic fields. Such sensors have been deployed in the field for the measurement of, e.g. biological systems, representing a promising practical application of quantum technologies. However, it remains challenging to obtain high-resolution magnetic field images from these sensors, and in most cases the spatial resolution of the system is limited by the sensor size. Here, we demonstrate the combination of single-pixel imaging (SPI) techniques with an atom vapor. Faraday magnetometer to achieve microscopic magnetic field imaging. We demonstrate magnetic field imaging with a spatial resolution of $\approx~62.5μm$ , limited only by the resolution of our DMD projection system and the absence of magnetic shielding in our experimental setup.In recent years, sensors based on hot atomic vapor cells have emerged as a compact and highly sensitive means of measuring magnetic fields. Such sensors have been deployed in the field for the measurement of, e.g. biological systems, representing a promising practical application of quantum technologies. However, it remains challenging to obtain high-resolution magnetic field images from these sensors, and in most cases the spatial resolution of the system is limited by the sensor size. Here, we demonstrate the combination of single-pixel imaging (SPI) techniques with an atom vapor. Faraday magnetometer to achieve microscopic magnetic field imaging. We demonstrate magnetic field imaging with a spatial resolution of $\approx~62.5μm$, limited only by the resolution of our DMD projection system and the absence of magnetic shielding in our experimental setup.

arXiv:2508.13869Aug 19, 20250 citations

Microscopic Magnetic Field Imaging with Hot Atoms

Jordan Brass, Sebastien Bisdee, Mohammed T. Rasheed +2 more

In the recent years, atomic sensors have demonstrated superior performance in magnetic field sensing compared to other technologies [1]. While atomic vapour cells have been integrated into compact systems, such as bio- imaging, the spatial resolution remains limited by the size of the sensors [2]. Here, we propose combining single- pixel imaging (SPI) technique with an atomic vapour cell to achieve microscopic-scale imaging for magnetic field sensing. The SPI technique involves projecting pattern of light onto a sample while monitoring the intensity [3]. The magnetic field is then estimated using the Faraday effect, where an incident linear polarised beam rotates in the presence of a magnetic field as the probe beam propagates through the atomic vapour cell.In the recent years, atomic sensors have demonstrated superior performance in magnetic field sensing compared to other technologies [1]. While atomic vapour cells have been integrated into compact systems, such as bio- imaging, the spatial resolution remains limited by the size of the sensors [2]. Here, we propose combining single- pixel imaging (SPI) technique with an atomic vapour cell to achieve microscopic-scale imaging for magnetic field sensing. The SPI technique involves projecting pattern of light onto a sample while monitoring the intensity [3]. The magnetic field is then estimated using the Faraday effect, where an incident linear polarised beam rotates in the presence of a magnetic field as the probe beam propagates through the atomic vapour cell.

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)Jun 23, 20250 citations

Mems-Enabled Quantum Atomic Magnetometers

Sean Krzyzewski, Orang Alem, Svenja A. Knappe

Sensors based on quantum-effects in atoms have seen rapid transitions from proof-of-principle experiments to commercial devices. Quantum atomic magnetometers based on alkali vapor cells benefit from high sensitivities combined with simple optical setups. This can be beneficial for magnetic imaging applications that need large numbers of pixels. We have designed a magnetographic proof-of-principle camera. We evaluated the detections limits for magnetic fields on a single pixel as a function of pixel size and compared it to our theoretical predictions. With this, we conclude that a camera with a sensitivity of on the order of 200 fT/√Hz, a pixel size of (100 μm)3should be scalable large arrays of pixels in the future.Sensors based on quantum-effects in atoms have seen rapid transitions from proof-of-principle experiments to commercial devices. Quantum atomic magnetometers based on alkali vapor cells benefit from high sensitivities combined with simple optical setups. This can be beneficial for magnetic imaging applications that need large numbers of pixels. We have designed a magnetographic proof-of-principle camera. We evaluated the detections limits for magnetic fields on a single pixel as a function of pixel size and compared it to our theoretical predictions. With this, we conclude that a camera with a sensitivity of on the order of 200 fT/√Hz, a pixel size of (100 μm)3should be scalable large arrays of pixels in the future.

IEEE International Conference on Micro Electro Mechanical Systems (MEMS)Jan 25, 20211 citation

Submillimeter-resolution magnetic field imaging with digital micromirror device and atomic vapor cell

Chen Liu, Haifeng Dong, Junjun Sang

Magnetic field source localization and imaging happen at different scales. The sensing baseline ranges from meter scale, such as magnetic anomaly detection, to centimeter scale, such as brain field imaging, to nanometer scale, such as the imaging of a magnetic skyrmion and single cell. Here, we show how an atomic vapor cell can be used to realize a baseline of 109.6 μm with a magnetic sensitivity of 10 pT/Hz1/2 @0.6–100 Hz and a dynamic range of 2062–4124 nT. We used a free induction decay (FID) scheme to suppress low-frequency noise and avoid scale factor variation for different domains due to light non-uniformity. The measurement domains are scanned by a digital micromirror device. The currents of 22, 30, 38, and 44 mA are applied in the coils to generate different fields along the pumping axis, which are measured respectively by fitting the FID signals of the probe light. The residual fields of every domain are obtained from the intercept of linearly fitting of the measurement data corresponding to these four currents. The coil-generated fields are calculated by deducting the residual fields from the total fields. The results demonstrate that the hole of shield affects both the residual and the coil-generated field distribution. The potential impact of field distribution measurement with outstanding comprehensive properties of spatial resolution, sensitivity, and dynamic range is far-reaching. It could lead to capability of 3D magnetography for small things and/or organs in millimeter or even smaller scale.Magnetic field source localization and imaging happen at different scales. The sensing baseline ranges from meter scale, such as magnetic anomaly detection, to centimeter scale, such as brain field imaging, to nanometer scale, such as the imaging of a magnetic skyrmion and single cell. Here, we show how an atomic vapor cell can be used to realize a baseline of 109.6 μm with a magnetic sensitivity of 10 pT/Hz1/2 @0.6–100 Hz and a dynamic range of 2062–4124 nT. We used a free induction decay (FID) scheme to suppress low-frequency noise and avoid scale factor variation for different domains due to light non-uniformity. The measurement domains are scanned by a digital micromirror device. The currents of 22, 30, 38, and 44 mA are applied in the coils to generate different fields along the pumping axis, which are measured respectively by fitting the FID signals of the probe light. The residual fields of every domain are obtained from the intercept of linearly fitting of the measurement data corresponding to these four currents. The coil-generated fields are calculated by deducting the residual fields from the total fields. The results demonstrate that the hole of shield affects both the residual and the coil-generated field distribution. The potential impact of field distribution measurement with outstanding comprehensive properties of spatial resolution, sensitivity, and dynamic range is far-reaching. It could lead to capability of 3D magnetography for small things and/or organs in millimeter or even smaller scale.

arXiv:2106.15310Applied Physics LettersSep 13, 202117 citations

Simple microwave field imaging technique using hot atomic vapor cells

Pascal Böhi, Philipp Treutlein

We demonstrate a simple technique for microwave field imaging using alkali atoms in a vapor cell. The microwave field to be measured drives Rabi oscillations on atomic hyperfine transitions, which are detected in a spatially resolved way using a laser beam and a camera. Our vapor cell geometry enables single-shot recording of two-dimensional microwave field images with 350 μm spatial resolution. Using microfabricated vapor cell arrays, a resolution of a few micrometers seems feasible. All vector components of the microwave magnetic field can be imaged. Our apparatus is simple and compact and does not require cryogenics or ultra-high vacuum.We demonstrate a simple technique for microwave field imaging using alkali atoms in a vapor cell. The microwave field to be measured drives Rabi oscillations on atomic hyperfine transitions, which are detected in a spatially resolved way using a laser beam and a camera. Our vapor cell geometry enables single-shot recording of two-dimensional microwave field images with 350 μm spatial resolution. Using microfabricated vapor cell arrays, a resolution of a few micrometers seems feasible. All vector components of the microwave magnetic field can be imaged. Our apparatus is simple and compact and does not require cryogenics or ultra-high vacuum.

arXiv:1207.4964Applied Physics LettersOct 29, 201269 citations

High resolution field imaging with atomic vapor cells

Andrew Horsley

In this thesis, I report on the development of imaging techniques in atomic vapor cells. This is a relatively unexplored area, despite the ubiquitous use of imaging in experiments with ultracold atoms. Our main focus is in high resolution imaging of microwave near fields, for which there is currently no satisfactory established technique. We detect microwave fields through Rabi oscillations driven by the microwave on atomic hyperfine transitions. The technique can be easily modified to also image dc magnetic fields. In addition, we have developed techniques to image vapor cell processes such as atomic T1 and T2 relaxation. These provide a new window into vapor cell physics, which we have used to obtain spatially resolved information on Rb interactions with the cell walls, and to estimate the Rb relaxation probability in a collision with the cell wall. \n \nAs a first application of our imaging techniques, we imaged the dc and microwave magnetic fields inside a state-of-the-art vapor cell atomic clock. This new clock characterisation technique should lead to real improvements in clock performance, and is in the process of being adopted by the atomic clock community. \n \nWe have developed a widefield, high resolution imaging setup using a microfabricated vapor cell, which we have used to image microwave and dc magnetic vector fields. With the addition of a 480 nm laser, the setup can be configured to image microwave electric fields. Our camera-based imaging system records 2D images with a 6x6 mm2 field of view at a rate of 10 Hz. It provides up to 50 um spatial resolution, and allows imaging of fields as close as 150 um above structures, through the use of extremely thin external cell walls. This is crucial in allowing us to take practical advantage of the high spatial resolution, as feature sizes in near-fields are on the order of the distance from their source, and represents an order of magnitude improvement in surface-feature resolution compared to previous vapor cell experiments. We demonstrate a microwave magnetic field sensitivity of 1.4 uT/sqrt-Hz per 50x50x140 um3 voxel, at present limited by the speed of our imaging system. Since we image 120x120 voxels in parallel, a single scanned sensor would require a sensitivity of at least 12 nT/sqrt-Hz to produce images with the same sensitivity. \n \nThe spatial resolution, distance of approach, and sensitivity of our high resolution setup are sufficient for characterising 6.8 GHz microwave fields above a range of real world devices. However, frequency tunability is essential for wider applications of our imaging technique. Industry is particularly interested in techniques for imaging high frequency microwaves, above 18 GHz, where simulations become increasingly unreliable. I have shown that our technique can be extended to image microwaves of any frequency, in principle from dc to 100s of GHz, by using a large dc magnetic field to Zeeman shift the hyperfine ground state transitions to the desired frequency. I present results from a proof-of-principle setup, where we have used a 0.8 T solenoid to detect and image microwaves from 2.3 GHz to 26.4 GHz. \nIn this thesis, I report on the development of imaging techniques in atomic vapor cells. This is a relatively unexplored area, despite the ubiquitous use of imaging in experiments with ultracold atoms. Our main focus is in high resolution imaging of microwave near fields, for which there is currently no satisfactory established technique. We detect microwave fields through Rabi oscillations driven by the microwave on atomic hyperfine transitions. The technique can be easily modified to also image dc magnetic fields. In addition, we have developed techniques to image vapor cell processes such as atomic T1 and T2 relaxation. These provide a new window into vapor cell physics, which we have used to obtain spatially resolved information on Rb interactions with the cell walls, and to estimate the Rb relaxation probability in a collision with the cell wall. \n \nAs a first application of our imaging techniques, we imaged the dc and microwave magnetic fields inside a state-of-the-art vapor cell atomic clock. This new clock characterisation technique should lead to real improvements in clock performance, and is in the process of being adopted by the atomic clock community. \n \nWe have developed a widefield, high resolution imaging setup using a microfabricated vapor cell, which we have used to image microwave and dc magnetic vector fields. With the addition of a 480 nm laser, the setup can be configured to image microwave electric fields. Our camera-based imaging system records 2D images with a 6x6 mm2 field of view at a rate of 10 Hz. It provides up to 50 um spatial resolution, and allows imaging of fields as close as 150 um above structures, through the use of extremely thin external cell walls. This is crucial in allowing us to take practical advantage of the high spatial resolution, as feature sizes in near-fields are on the order of the distance from their source, and represents an order of magnitude improvement in surface-feature resolution compared to previous vapor cell experiments. We demonstrate a microwave magnetic field sensitivity of 1.4 uT/sqrt-Hz per 50x50x140 um3 voxel, at present limited by the speed of our imaging system. Since we image 120x120 voxels in parallel, a single scanned sensor would require a sensitivity of at least 12 nT/sqrt-Hz to produce images with the same sensitivity. \n \nThe spatial resolution, distance of approach, and sensitivity of our high resolution setup are sufficient for characterising 6.8 GHz microwave fields above a range of real world devices. However, frequency tunability is essential for wider applications of our imaging technique. Industry is particularly interested in techniques for imaging high frequency microwaves, above 18 GHz, where simulations become increasingly unreliable. I have shown that our technique can be extended to image microwaves of any frequency, in principle from dc to 100s of GHz, by using a large dc magnetic field to Zeeman shift the hyperfine ground state transitions to the desired frequency. I present results from a proof-of-principle setup, where we have used a 0.8 T solenoid to detect and image microwaves from 2.3 GHz to 26.4 GHz. \n

Jan 1, 20151 citation

\approx~62.5μm

, limited only by the resolution of our DMD projection system and the absence of magnetic shielding in our experimental setup.