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Optical Magnetometry

Book Description

Featuring chapters written by leading experts in magnetometry, this book provides comprehensive coverage of the principles, technology and diverse applications of optical magnetometry, from testing fundamental laws of nature to detecting biomagnetic fields and medical diagnostics. Readers will find a wealth of technical information, from antirelaxation-coating techniques, microfabrication and magnetic shielding to geomagnetic-field measurements, space magnetometry, detection of biomagnetic fields, detection of NMR and MRI signals and rotation sensing. The book includes an original survey of the history of optical magnetometry and a chapter on the commercial use of these technologies. The book is supported by extensive online material, containing historical overviews, derivations, sideline discussion, additional plots and tables, available at www.cambridge.org/9781107010352. As well as introducing graduate students to this field, the book is also a useful reference for researchers in atomic physics.

Note:The ebook version does not provide access to the companion files.

Table of Contents

  1. Cover
  2. Title page
  3. Copyright
  4. Contents
  5. List of contributors
  6. Preface
  7. Part I  Principles and techniques
    1. 1    General principles and characteristics of optical magnetometers
      1. 1.1    Introduction
        1. 1.1.1      Fundamental sensitivity limits
        2. 1.1.2      Zeeman shifts and atomic spin precession
        3. 1.1.3      Quantum beats and dynamic range
      2. 1.2    Model of an optical magnetometer
      3. 1.3    Density matrix and atomic polarization moments
      4. 1.4    Sensitivity and accuracy
        1. 1.4.1      Variational sensitivity (short-term resolution) and long-term stability
        2. 1.4.2      Parameter optimization
        3. 1.4.3      Absolute accuracy and systematic errors
      5. 1.5    Vector and scalar magnetometers
      6. 1.6    Applications
    2. 2    Quantum noise in atomic magnetometers
      1. 2.1    Introduction
      2. 2.2    Spin-projection noise
      3. 2.3    Faraday rotation measurements
      4. 2.4    Quantum back-action
      5. 2.5    Time correlation of spin-projection noise
      6. 2.6    Conditions for spin-noise dominance
      7. 2.7    Spin projection limits on magnetic field sensitivity
      8. 2.8    Spin squeezing and atomic magnetometry
      9. 2.9    Conclusion
    3. 3    Quantum noise, squeezing, and entanglement in radiofrequency optical magnetometers
      1. 3.1    Sources of noise
        1. 3.1.1      Atomic projection noise
        2. 3.1.2      Photon shot noise
        3. 3.1.3      Back-action noise and QND measurements
        4. 3.1.4      Technical (classical) noise
        5. 3.1.5      Entanglement and spin squeezing
      2. 3.2    A pulsed radiofrequency magnetometer and the projection noise limit
        1. 3.2.1      Pulsed RF magnetometry
        2. 3.2.2      Sensitivity and bandwidth
      3. 3.3    Light-atom interaction
        1. 3.3.1      A spin-polarized atomic ensemble interacting with polarized light
        2. 3.3.2      Conditional spin squeezing
        3. 3.3.3      Larmor precession, back-action noise, and two atomic ensembles
        4. 3.3.4      Swap and squeezing interaction
      4. 3.4    Demonstration of high-sensitivity, projection-noise-limited magnetometry
        1. 3.4.1      Setup, pulse sequence, and procedure
        2. 3.4.2      The projection-noise-limited magnetometer
      5. 3.5    Demonstration of entanglement-assisted magnetometry
      6. 3.6    Conclusions
    4. 4    Mx and Mz magnetometers
      1. 4.1    Dynamics of magnetic resonance in an alternating field
        1. 4.1.1      Bloch equations and Bloch sphere
        2. 4.1.2      Types of magnetic resonance signals: Mz and Mx signals
      2. 4.2    Mz and Mx magnetometers: general principles
        1. 4.2.1      Advantages and disadvantages of Mz magnetometers
        2. 4.2.2      Advantages and disadvantages of Mx magnetometers
        3. 4.2.3      Attempts to combine advantages of Mx and Mz magnetometers: Mx-Mz tandems
      3. 4.3    Applications: radio-optical Mx and Mz magnetometers
        1. 4.3.1      Alkali Mz magnetometers
        2. 4.3.2      Mx magnetometers
        3. 4.3.3      Mx-Mz tandems
      4. 4.4    Summary: Mx and Mz scheme limitations, prospects, and application areas
    5. 5    Spin-exchange-relaxation-free (SERF) magnetometers
      1. 5.1    Introduction
      2. 5.2    Spin-exchange collisions
        1. 5.2.1      The density-matrix equation
        2. 5.2.2      Simple model of spin exchange
      3. 5.3    Bloch equation description
      4. 5.4    Experimental realization
        1. 5.4.1      Classic SERF atomic magnetometer arrangement
        2. 5.4.2      Zeroing the magnetic field
        3. 5.4.3      Use of antirelaxation coatings
        4. 5.4.4      Comparison with SQUIDs
      5. 5.5    Fundamental sensitivity
    6. 6    Optical magnetometry with modulated light
      1. 6.1    Introduction
      2. 6.2    Typical experimental arrangements
      3. 6.3    Resonances in the magnetic field dependence
        1. 6.3.1      Frequency modulation
        2. 6.3.2      Amplitude modulation
        3. 6.3.3      Polarization modulation
      4. 6.4    Effects at high light powers
      5. 6.5    Nonlinear Zeeman effect
      6. 6.6    Magnetometric measurements with modulated light
      7. 6.7    Conclusion
    7. 7    Microfabricated atomic magnetometers
      1. 7.1    Introduction
      2. 7.2    Sensitivity scaling with size
      3. 7.3    Sensor fabrication
      4. 7.4    Vapor cells
      5. 7.5    Heating and thermal management
      6. 7.6    Performance
      7. 7.7    Applications of microfabricated magnetometers
      8. 7.8    Outlook
    8. 8    Optical magnetometry with nitrogen-vacancy centers in diamond
      1. 8.1    Introduction
        1. 8.1.1      Comparison with existing technologies
      2. 8.2    Historical background
        1. 8.2.1      Single-spin optically detected magnetic resonance
      3. 8.3    NV center physics
        1. 8.3.1      Intersystem crossing and optical pumping
        2. 8.3.2      Ground-state level structure and ODMR-based magnetometry
        3. 8.3.3      Interaction with environment
      4. 8.4    Experimental realizations
        1. 8.4.1      Near-field scanning probes and single-NV magnetometry
        2. 8.4.2      Wide-field array magnetic imaging
        3. 8.4.3      NV-ensemble magnetometers
      5. 8.5    Outlook
    9. 9    Magnetometry with cold atoms
      1. 9.1    Introduction
      2. 9.2    Experimental conditions
        1. 9.2.1      Constraints and advantages of using cold atoms for magnetometry
        2. 9.2.2      Cold samples of atoms above quantum degeneracy
      3. 9.3    Linear Faraday rotation with trapped atoms
      4. 9.4    Nonlinear Faraday rotation
        1. 9.4.1      Low-field, DC magnetometry
        2. 9.4.2      Coherence evolution
        3. 9.4.3      High-field, amplitude-modulated magneto-optical rotation
        4. 9.4.4      Paramagnetic nonlinear rotation
      5. 9.5    Magnetometry with ultra-cold atoms
        1. 9.5.1      Overview of ultra-cold atomic magnetometry methods
        2. 9.5.2      Figures of merit
        3. 9.5.3      Details of spinor magnetometry
        4. 9.5.4      Comparison with thermal-atom magnetometry
        5. 9.5.5      Applications
    10. 10  Helium magnetometers
      1. 10.1  Introduction
      2. 10.2  Helium magnetometer principles of operation
        1. 10.2.1    Helium resonance element
        2. 10.2.2    Helium optical pumping radiation sources
        3. 10.2.3    Optical pumping of metastable helium
        4. 10.2.4    Observation of optically pumped helium
        5. 10.2.5    Observation of magnetic resonance signals in optically pumped helium
      3. 10.3  Conclusions
    11. 11  Surface coatings for atomic magnetometry
      1. 11.1  Introduction and history
      2. 11.2  Wall relaxation mechanisms
        1. 11.2.1    Origin and time dependence of the disorienting interaction
        2. 11.2.2    Methods of investigation
        3. 11.2.3    Quantitative interpretation
      3. 11.3  Coating preparation
      4. 11.4  Light-induced atomic desorption (LIAD)
      5. 11.5  Recent characterization methods
    12. 12  Magnetic shielding
      1. 12.1  Introduction
      2. 12.2  Ferromagnetic shielding
        1. 12.2.1    Simplified estimation of ferromagnetic shielding efficiency for a static magnetic field
        2. 12.2.2    Multilayer ferromagnetic shielding
        3. 12.2.3    Optimization of permeability: annealing, degaussing, shaking, tapping
        4. 12.2.4    Magnetic-field noise in ferromagnetic shielding
        5. 12.2.5    Examples of ferromagnetic shielding systems
      3. 12.3  Ferrite shields
        1. 12.3.1    Permeability
        2. 12.3.2    Fabrication and the effect of an air gap
        3. 12.3.3    Thermal noise
      4. 12.4  Superconducting shields
        1. 12.4.1    Principles
        2. 12.4.2    Materials and fabrication
        3. 12.4.3    Image field
  8. Part II  Applications
    1. 13  Remote detection magnetometry
      1. 13.1  Introduction
      2. 13.2  A remotely interrogated all-optical 87Rb magnetometer
      3. 13.3  Magnetometry with mesospheric sodium
    2. 14  Detection of nuclear magnetic resonance with atomic magnetometers
      1. 14.1  Introduction
      2. 14.2  The NMR Hamiltonian
      3. 14.3  Challenges associated with detection of NMR using atomic magnetometers
      4. 14.4  Remote detection
      5. 14.5  Solenoid matching of Zeeman resonance frequencies
      6. 14.6  Flux transformer
      7. 14.7  Nuclear quadrupole resonance
      8. 14.8  Zero-field nuclear magnetic resonance
        1. 14.8.1    Thermally polarized zero-field NMR J spectroscopy
        2. 14.8.2    Parahydrogen-enhanced zero-field NMR
        3. 14.8.3    Zeeman effects on J-coupled multiplets
      9. 14.9  Conclusions
    3. 15  Space magnetometry
      1. 15.1  Introduction
        1. 15.1.1    Achievements of space magnetometry
        2. 15.1.2    Challenges unique to space magnetometers
        3. 15.1.3    Magnetic sensors used in space missions
      2. 15.2  Alkali-vapor magnetometers in space applications
        1. 15.2.1    Initial development of Earth’s-field alkali magnetometers
        2. 15.2.2    Sensor design
        3. 15.2.3    NASA missions employing alkali-vapor magnetometers
      3. 15.3  Helium magnetometers in space applications
        1. 15.3.1    Introduction
        2. 15.3.2    Future helium space magnetometers
    4. 16  Detection of biomagnetic fields
      1. 16.1  Sources of biomagnetism
      2. 16.2  Development of biomagnetic field detection
      3. 16.3  Medical applications
      4. 16.4  Magnetocardiography with atomic magnetometers
      5. 16.5  Magnetoencephalography with an atomic magnetometer
      6. 16.6  Summary
    5. 17  Geophysical applications
      1. 17.1  Airborne magnetometers and gradiometers
      2. 17.2  Ground magnetometers/gradiometers
      3. 17.3  Marine magnetometers/gradiometers
      4. 17.4  Vector magnetometry with optically pumped magnetometers
      5. 17.5  Earthquake studies
      6. 17.6  Applications of magnetometers to detecting unexploded ordnance (UXO)
        1. 17.6.1    Introduction to the problem
        2. 17.6.2    Using magnetometers for UXO detection
        3. 17.6.3    Mathematics of UXO detection
  9. Part III  Broader impact
    1. 18  Tests of fundamental physics with optical magnetometers
      1. 18.1  Overview and introduction
      2. 18.2  Searches for permanent electric dipole moments
        1. 18.2.1    Basic experimental setup for an EDM experiment
        2. 18.2.2    Sensitivity to EDMs
        3. 18.2.3    Electric fields and coherence times for various systems
        4. 18.2.4    Magnetometry and comagnetometry in EDM experiments
      3. 18.3  Anomalous spin-dependent forces
        1. 18.3.1    Background
        2. 18.3.2    Experiments
      4. 18.4  CPTand local Lorentz invariance tests
      5. 18.5  Conclusion
    2. 19  Nuclear magnetic resonance gyroscopes
      1. 19.1  Introduction
      2. 19.2  NMR frequency shifts and relaxation
        1. 19.2.1    Spin exchange
        2. 19.2.2    Quadrupole surface frequency shifts
        3. 19.2.3    General wall relaxation
        4. 19.2.4    Magnetic-field gradients
        5. 19.2.5    Noble-gas self-relaxation
      3. 19.3  Alkali shifts and relaxation mechanisms
      4. 19.4  Two-spin NMR gyroscope
      5. 19.5  Comagnetometer
      6. 19.6  Miniaturization
      7. 19.7  Conclusion
    3. 20  Commercial magnetometers and their application
      1. 20.1  Introduction
      2. 20.2  Specifications
        1. 20.2.1    Noise
        2. 20.2.2    Resolution
        3. 20.2.3    Sensitivity
        4. 20.2.4    Sample rate and cycle time
        5. 20.2.5    Bandwidth
        6. 20.2.6    Absolute error and drift
        7. 20.2.7    Gradient tolerance
        8. 20.2.8    Dead zones
        9. 20.2.9    Heading error
        10. 20.2.10  Range of measurement
      3. 20.3  History of commercial magnetometry
        1. 20.3.1    Fluxgate magnetometers
        2. 20.3.2    SQUID magnetometers
        3. 20.3.3    Proton-precession and Overhauser magnetometers
        4. 20.3.4    Alkali metal magnetometers: rubidium, cesium, and potassium
        5. 20.3.5    Helium-3 and helium-4 magnetometers
      4. 20.4  Military applications
      5. 20.5  Anticipated improvements
  10. Index