Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:2412.02686 · Applied Physics Letters

Electron beam characterization via quantum coherent optical magnetometry

Nicolas DeStefano, Saeed Pegahan, Aneesh Ramaswamy, S. Aubin, Todd D. Averett, A. Camsonne, Svetlana Malinovskaya, Eugeniy E. Mikhailov, Gunn-Tae Park, Shukui Zhang, Irina V. Novikova

Published Dec 23, 2024• 4 citations
arXivHTMLPDF

Abstract

We present a quantum optics-based detection method for determining the position and current of an electron beam. As electrons pass through a dilute vapor of rubidium atoms, their magnetic field perturbs the atomic spin's quantum state and causes polarization rotation of a laser resonant with an optical transition of the atoms. By measuring the polarization rotation angle across the laser beam, we recreate a 2D projection of the magnetic field and use it to determine the e-beam position, size, and total current. We tested this method for an e-beam with currents ranging from 30 to 110 μA. Our approach is insensitive to electron kinetic energy, and we confirmed that experimentally between 10 and 20 keV. This technique offers a unique platform for noninvasive characterization of charged particle beams used in accelerators for particle and nuclear physics research.

DOI
10.1063/5.0234219

Related papers

Electron beam characterization via quantum coherent electric field imaging

Rob Behary, Kevin Su, Nicolas DeStefano +9 more

We demonstrate an all-optical, minimally invasive electron beam ( e − beam ) characterization using Rydberg electrometry. An e -beam passes through a localized detector volume containing thermal Rb atoms that are optically excited in a quantum superposition of ground and Rydberg states. The e -beam's electric field perturbs atomic coherence and modifies resonance fluorescence in a narrow spectral region near the two-photon optical transition. Imaging Rb fluorescence provides a map of the electric field from the e -beam via Rydberg state Stark shifts and allows us to reconstruct the e -beam width, centroid position, and current. For an e -beam of 20 keV and electron currents of 20–40 µ A , we measured the centroid position with an accuracy of ≤ 8 µ m and width to within 100 µ m , limited by the experimental sensitivity of electric field reconstruction of ∼ 0.02 V/cm. This method is suitable for a wide range of electron energies and currents, and can be adopted for nuclear and high-energy experiments for minimally invasive real-time diagnostics and profiling of charged particle beams.

arXiv:2504.21144•Physical Review Research•Oct 19, 2025•5 citations

Electron Beam Profiling via Rydberg Electromagnetically Induced Transparency in Rubidium Vapor with Crossed Laser beams

Rob Behary, Kevin Su, Nicolas DeStefano +9 more

We present an all-optical detection approach to determine the position and spatial profile of an electron beam based on quantum properties of alkali metal atoms. To measure the electric field, produced by an electron beam, we excite thermal rubidium atoms to a highly excited Rydberg state via a two-photon ladder transition and detect Stark shifts of Rydberg states by monitoring frequencies of the corresponding electromagnetically induced transparency (EIT) transmission peaks. We addressed several technical challenges in this approach. First, we use crossed laser beams to obtain spatial information about the electron beam position and geometry. Second, by pulsing the electron beam and using phase-sensitive optical detection, we separate the true electron beam electric signature from the parasitic electric fields due to photoelectric charges on the windows. Finally, we use a principle component analysis to further improve signal quality. We test this method to detect the current and to reconstruct a 2D profile of a 20 keV electron beam with currents ranging from 25 - 100 uA. While this technique provides less spatial resolution than fluorescence-based measurements, thanks to their speed and limited optical access requirements it can be useful for real-time non-invasive diagnostics of charged particle beams at accelerator facilities.

arXiv:2601.02549•Jan 5, 2026•1 citation

Magnetometry with Microwave-Assisted Optical Pumping in Warm Rb Vapor and Microfabricated Rb Vapor Cells

Lu, Ying-Ying

Quantum optical sensing is a maturing field that offers the capability to achieve extraor- dinary sensitivity. Atomic magnetometers, for example, now have the capability to detect brain signals and to precisely measure Earth’s gravity field. In optical atomic magnetome- ters, the electronic spins of the atoms in vapor form are aligned in the same direction by “pumping” the ensemble using laser light at a select frequency. Any magnetic field alters the spin states, which changes the optical properties of the vapor, such as the transmission of the laser light, providing a way to measure magnetic fields. After reviewing the theory of atomic structure and atom-light interactions relevant to the research presented here, I describe in the first part of this thesis a vector magnetometry method using microwave-assisted optical pumping, in which a microwave field resonant to the ground state hyperfine splitting of 87Rb pumps an ensemble of warm rubidium vapor, in addition to a strong optical pump beam, and a weaker optical probe beam. I present theoretical details as well as preliminary data demonstrating magnetic field measurements of a DC magnetic field. The measurements were taken when the DC field was aligned at various angles relative to the microwave magnetic field alignment. I compare theoretical and experimental differences in the measurements. With new methods for quantum devices comes the need for portability. In the second part of this thesis, we demonstrate the fabrication of millimeter-sized rubidium vapor cells using silicon micro-machining techniques. This method is relatively inexpensive compared to glass-blowing methods and allows rapid, large-scale production. I describe our process flow and demonstrate the presence of rubidium atoms inside our vapor cells. To conclude, suggestions for improvement are discussed.

•Jan 1, 2021•0 citations

Structured-Light Magnetometry in a Coherently Controlled Atomic Medium

Parkhi Bhardwaj, Shubhrangshu Dasgupta

A structured-light-based approach to magneto-optical rotation (MOR) magnetometry is proposed, in which magnetically induced polarization rotation is converted into a directly observable spatial displacement. A radially polarized Laguerre--Gaussian beam propagating through cold $^{87}\mathrm{Rb}$ atoms in the presence of a longitudinal magnetic field experiences circular birefringence, which induces a relative phase shift between the $σ_+$ and $σ_-$ polarization components. This phase shift manifests itself as the angular rotation of a petal-shaped interference pattern, enabling the MOR angle to be determined directly from the spatial intensity distribution. Unlike conventional MOR detection techniques based on balanced polarimetry or Stokes-parameter reconstruction, the proposed method requires only a fixed-axis polarization projection and avoids computationally intensive polarization analysis. By translating polarization rotation into a topology-dependent spatial observable, the scheme enables direct and spatially resolved magnetic-field measurements. Furthermore, the use of electromagnetically induced transparency (EIT) allows low-loss operation while preserving high sensitivity. These characteristics make the proposed technique a promising platform for optical magnetometry and structured-light-based quantum sensing.

physics.atom-phCross-listedarXiv:2603.25781•Mar 27, 2026•0 citations

Electron Beam Profiling Using Coherent Atomic Magnetometry

Nicolas DeStefano, Todd D. Averett, Shukui Zhang +7 more

We reconstruct 2-D electron beam profiles using local measurements of its magnetic field via nonlinear magneto-optical polarization rotation in Rb vapor.

•Jan 1, 2024•0 citations

Electron Beam Profiling Using Coherent Atomic Magnetometry

Nicolas DeStefano, Todd D. Averett, Shukui Zhang +6 more

We image 2-D electron beam profiles through localized measurements of its magnetic field using nonlinear magneto-optical polarization rotation in hot Rb vapor.

Frontiers in Optics•Jan 1, 2024•0 citations
We present a quantum optics-based detection method for determining the position and current of an electron beam. As electrons pass through a dilute vapor of rubidium atoms, their magnetic field perturbs the atomic spin's quantum state and causes polarization rotation of a laser resonant with an optical transition of the atoms. By measuring the polarization rotation angle across the laser beam, we recreate a 2D projection of the magnetic field and use it to determine the e-beam position, size, and total current. We tested this method for an e-beam with currents ranging from 30 to 110 μA. Our approach is insensitive to electron kinetic energy, and we confirmed that experimentally between 10 and 20 keV. This technique offers a unique platform for noninvasive characterization of charged particle beams used in accelerators for particle and nuclear physics research.
We demonstrate an all-optical, minimally invasive electron beam ( e − beam ) characterization using Rydberg electrometry. An e -beam passes through a localized detector volume containing thermal Rb atoms that are optically excited in a quantum superposition of ground and Rydberg states. The e -beam's electric field perturbs atomic coherence and modifies resonance fluorescence in a narrow spectral region near the two-photon optical transition. Imaging Rb fluorescence provides a map of the electric field from the e -beam via Rydberg state Stark shifts and allows us to reconstruct the e -beam width, centroid position, and current. For an e -beam of 20 keV and electron currents of 20–40 µ A , we measured the centroid position with an accuracy of ≤ 8 µ m and width to within 100 µ m , limited by the experimental sensitivity of electric field reconstruction of ∼ 0.02 V/cm. This method is suitable for a wide range of electron energies and currents, and can be adopted for nuclear and high-energy experiments for minimally invasive real-time diagnostics and profiling of charged particle beams.
We present an all-optical detection approach to determine the position and spatial profile of an electron beam based on quantum properties of alkali metal atoms. To measure the electric field, produced by an electron beam, we excite thermal rubidium atoms to a highly excited Rydberg state via a two-photon ladder transition and detect Stark shifts of Rydberg states by monitoring frequencies of the corresponding electromagnetically induced transparency (EIT) transmission peaks. We addressed several technical challenges in this approach. First, we use crossed laser beams to obtain spatial information about the electron beam position and geometry. Second, by pulsing the electron beam and using phase-sensitive optical detection, we separate the true electron beam electric signature from the parasitic electric fields due to photoelectric charges on the windows. Finally, we use a principle component analysis to further improve signal quality. We test this method to detect the current and to reconstruct a 2D profile of a 20 keV electron beam with currents ranging from 25 - 100 uA. While this technique provides less spatial resolution than fluorescence-based measurements, thanks to their speed and limited optical access requirements it can be useful for real-time non-invasive diagnostics of charged particle beams at accelerator facilities.
Quantum optical sensing is a maturing field that offers the capability to achieve extraor- dinary sensitivity. Atomic magnetometers, for example, now have the capability to detect brain signals and to precisely measure Earth’s gravity field. In optical atomic magnetome- ters, the electronic spins of the atoms in vapor form are aligned in the same direction by “pumping” the ensemble using laser light at a select frequency. Any magnetic field alters the spin states, which changes the optical properties of the vapor, such as the transmission of the laser light, providing a way to measure magnetic fields. After reviewing the theory of atomic structure and atom-light interactions relevant to the research presented here, I describe in the first part of this thesis a vector magnetometry method using microwave-assisted optical pumping, in which a microwave field resonant to the ground state hyperfine splitting of 87Rb pumps an ensemble of warm rubidium vapor, in addition to a strong optical pump beam, and a weaker optical probe beam. I present theoretical details as well as preliminary data demonstrating magnetic field measurements of a DC magnetic field. The measurements were taken when the DC field was aligned at various angles relative to the microwave magnetic field alignment. I compare theoretical and experimental differences in the measurements. With new methods for quantum devices comes the need for portability. In the second part of this thesis, we demonstrate the fabrication of millimeter-sized rubidium vapor cells using silicon micro-machining techniques. This method is relatively inexpensive compared to glass-blowing methods and allows rapid, large-scale production. I describe our process flow and demonstrate the presence of rubidium atoms inside our vapor cells. To conclude, suggestions for improvement are discussed.
A structured-light-based approach to magneto-optical rotation (MOR) magnetometry is proposed, in which magnetically induced polarization rotation is converted into a directly observable spatial displacement. A radially polarized Laguerre--Gaussian beam propagating through cold 87Rb^{87}\mathrm{Rb}87Rb atoms in the presence of a longitudinal magnetic field experiences circular birefringence, which induces a relative phase shift between the σ+σ_+σ+​ and σ−σ_-σ−​ polarization components. This phase shift manifests itself as the angular rotation of a petal-shaped interference pattern, enabling the MOR angle to be determined directly from the spatial intensity distribution. Unlike conventional MOR detection techniques based on balanced polarimetry or Stokes-parameter reconstruction, the proposed method requires only a fixed-axis polarization projection and avoids computationally intensive polarization analysis. By translating polarization rotation into a topology-dependent spatial observable, the scheme enables direct and spatially resolved magnetic-field measurements. Furthermore, the use of electromagnetically induced transparency (EIT) allows low-loss operation while preserving high sensitivity. These characteristics make the proposed technique a promising platform for optical magnetometry and structured-light-based quantum sensing.