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.
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 ≈ 62.5 μm, limited only by the resolution of our digital micromirror device 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 ≈62.5μm, limited only by the resolution of our DMD projection system and the absence of magnetic shielding in our experimental setup.
Abstract The magnetic field is one of the most fundamental and ubiquitous physical observables, carrying information about all electromagnetic phenomena. For the past 30 years, superconducting quantum interference devices (SQUIDs) operating at 4 K have been unchallenged as ultrahigh-sensitivity magnetic field detectors1, with a sensitivity reaching down to 1 fT Hz-1/2 (1 fT = 10-15 T). They have enabled, for example, mapping of the magnetic fields produced by the brain, and localization of the underlying electrical activity (magnetoencephalography). Atomic magnetometers, based on detection of Larmor spin precession of optically pumped atoms, have approached similar levels of sensitivity using large measurement volumes2, 3, but have much lower sensitivity in the more compact designs required for magnetic imaging applications4. Higher sensitivity and spatial resolution combined with non-cryogenic operation of atomic magnetometers would enable new applications, including the possibility of mapping non-invasively the cortical modules in the brain. Here we describe a new spin-exchange relaxation-free (SERF) atomic magnetometer, and demonstrate magnetic field sensitivity of 0.54 fT Hz-1/2 with a measurement volume of only 0.3 cm3. Theoretical analysis shows that fundamental sensitivity limits of this device are below 0.01 fT Hz-1/2. We also demonstrate simple multichannel operation of the magnetometer, and localization of magnetic field sources with a resolution of 2 mm.
Abstract Optical magnetometers based on alkali vapors, such as rubidium, are among the most sensitive technologies for detecting and characterizing magnetic fields. Following the recent effort in miniaturizing atomic-based quantum technologies, the last years were marked by a growing interest in developing integrated quantum nanophotonic circuits for a vast range of applications. Motivated by the attractiveness of such chip-scale integration, we present and experimentally demonstrate an integrated magnetic sensing platform, based on a nanophotonic-chip interfaced to a microfabricated alkali vapor cell. Magnetically induced circular dichroism in rubidium vapor is measured using a planar structure that spatially resolves the handedness of incoming photons depending on their spin. The presented approach paves the way toward further integration of highly sensitive magnetometers, with potential for future applications, such as in high-spatial resolution magnetic vectorial imaging.
We demonstrate a single-beam atomic magnetometer (AM) capable of measuring a three-axis magnetic field with high-sensitivity, achieved by applying a small DC offset field and a high frequency modulation field. To satisfy the miniaturization demand of AMs, an elliptically polarized light detuned by 50 GHz from the resonance transition center is employed. The circularly polarized component is used to polarize the alkali-metal atoms, while the linearly polarized light is used to detect the dynamics of the polarized spin under a magnetic field. Based on theoretical analysis, parameters that significantly affect the performance are optimized, and a sensitivity of 20 fT/Hz 1/2 in x -axis, 25 fT/Hz 1/2 in y -axis, 30 fT/Hz 1/2 in z -axis is achieved with a miniature 4 × 4 × 4 mm 87 Rb vapor cell. Moreover, we also verify that the operation principle of AMs can be used to null background magnetic fields in-situ with isotropic compensation resolution of 6.7 pT, which provides an effectively precise method for zeroing ambient magnetic field. The high-sensitivity operating of an elliptically-polarized-laser-based magnetometer provides prospective futures for constructing a compact, low-cost AM, which is particularly applicable for non-invasive bio-magnetic imaging such as array-based magnetoencephalography (MEG) and magnetocardiography (MCG).
Emerging quantum sensing devices namely atomic magnetometers have become promising candidate for future biomagnetism imaging. However, the limitation of detection bandwidth exists a major drawback for devices of this kind. Conventional approaches, including transverse magnetic field modulation and close-loop control, have seen challenging tradeoffs between size, resolution and bandwidths. In this study, a wide bandwidth zero-field magnetometer with a miniaturized light source has been developed for alternating current (AC) magnetic field detection. A dual-beam Spin-Exchange Relaxation-Free (SERF) magnetometer employing a 4×4×4mm3 alkali metal vapor cell achieves a bandwidth of 188 Hz. This represents a threefold increase in bandwidth compared to non-modulated mode. The sensitivity under modulated mode demonstrated a sensitivity of 55fT/Hz1/2within the frequency range of 10-188Hz. Our results also demonstrated that the sensitivity is constrained by relaxation induced by the modulation of pumping source, so possible tradeoffs can be made based on various applications. The proposed method provides novel approach for bandwidth extension of atomic magnetometers which further pave the way for future applications including magnetoencephalography (MEG), particularly in reducing magnetic noise crosstalk and enhancing spatial resolution.