We demonstrate the possibility of dynamic imaging of magnetic fields using electromagnetically induced transparency in an atomic gas. As an experimental demonstration we employ an atomic Rb gas confined in a glass cell to image the transverse magnetic field created by a long straight wire. In this arrangement, which clearly reveals the essential effect, the field of view is about 2 x 2 mm(2) and the field detection uncertainty is 0.14 mG per 10 microm x 10 microm image pixel.
We demonstrate the possibility of dynamic imaging of magnetic fields using electromagnetically induced transparency in an atomic gas. As an experimental demonstration we employ an atomic Rb gas confined in a glass cell to image the transverse magnetic field created by a long straight wire. In this arrangement, which clearly reveals the essential effect, the field of view is about 2 x 2 mm(2) and the field detection uncertainty is 0.14 mG per 10 microm x 10 microm image pixel.
Abstract We have studied the phenomenon of electromagnetically induced transparency (EIT) of 87 Rb vapor at room temperature in a magnetic field with an arbitrary angle to the laser propagation direction. Rather than exposing atoms to a parallelled or transverse magnetic field as usual, in our work, we apply a magnetic field (up to 45 Gauss) with an arbitrary angle to the laser propagation direction and the spectra become much more complex. More EIT dips are observed due to the Zeeman splitting on the D 2 line of 87 Rb in a Λ -type configuration. With a 5 Torr N 2 buffer gas in the thermal 2 cm vapor cell, the state 5 2 P 3 / 2 has a very short effective lifetime, corresponding to a large energy broadening, which removes the velocity selective optical pumping effect almost completely and keeps the high resolution EIT spectrum for the energy splitting of 87 Rb in magnetic fields. The shifting of the EIT resonances with the strength of the applied magnetic field coincides well with the theory based on a full matrix Hamiltonian combined with a spectral decomposition method. Our work can be extended to measure the magnetic field vector in space. The effects of the detuning of the probe and coupling beams on the spectral lines are also investigated.
This project demonstrates an optical method for measuring the strength and\ndirection of a magnetic field using electromagnetically induced transparency\n(EIT) in rubidium vapor. In rubidium atoms, the Zeeman effect causes atomic\nstates to shift when an external magnetic field is applied. The magnitude of\nthese shifts, and consequently the strength of the magnetic field, can be measured\nby recording electromagnetically induced transparency resonances with\ntuned laser fields. Furthermore, since the atom's interaction with the laser field\nis dependent on the direction of the magnetic field and the laser polarization,\nwe are able to determine the direction as well as the strength of the magnetic\nfield by analyzing relative intensities of EIT resonances. With a feasible precision\ndown to 10 picoTesla and the possibility of complete field mapping, this\nmagnetometer can be useful for medical, geophysical, and materials testing\napplications.
Electromagnetically induced transparency (EIT) resonances are investigated with the 85Rb D 1 line (795 nm) in strong magnetic fields (up to 2 kG) with three different types of spectroscopic vapor cells: the nano-cell with a thickness along the direction of laser light L ≈ 795 nm, the micro-cell with L = 30 μm with the addition of a neon buffer gas, and the centimeter-long glass cell. These cells allowed us to observe systematic changes of the EIT spectra when the increasing magnetic field systematically decoupled the total atomic electron and nuclear angular moments (the Paschen-Back/Back-Goudsmit effects). The observations agree well with a theoretical model. The advantages and disadvantages of a particular type of cell are discussed along with the possible practical applications.
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. \n
We perform optical magnetic-resonance (MR) imaging of Cs atoms that are polarized by the transfer from the polarized Xe or Rb atoms in a glass cell as well as by direct optical pumping. With MR images of Cs by alternate optical pumping and detection the distribution of polarized Xe or Rb of low gas pressure is observed in a weak magnetic field. We also discuss the effect of the spin-relaxation and the spin-exchange collisions between Cs, Xe, and Rb atoms on the spatial resolution of MR images of the diffusing Cs atoms.
We demonstrate a new method for measuring magnetic gradients in the presence of large constant magnetic fields using electromagnetically induced transparency in rubidium vapor. As the Earth provides a near-constant magnetic field of 25-50 µT, most measurements of small magnetic fields involve subtracting or shielding the Earth's field. Our method can measure small gradients in the presence of large magnetic fields using Electromagnetically Induced Transparency in 87Rb. By comparing the resonances of two laser beams in a dual-rail arrangement propagating through rubidium vapor in a spatially changing magnetic field, we are able to measure a constant gradient of ≥7 nT/cm and a time-varying gradient of ≥50 pT/cm, over a constant magnetic field of 35 µT.