Related Experiment Video
Updated: Jun 14, 2026
09:43
Optimized Setup and Protocol for Magnetic Domain Imaging with In Situ Hysteresis Measurement
Published on: November 7, 2017
High bandwidth atomic magnetometery with continuous quantum nondemolition measurements.
V Shah1, G Vasilakis, M V Romalis
1Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
Physical Review Letters
|April 7, 2010
Summary
This study enhances alkali-metal magnetometer performance by using quantum nondemolition measurements. This boosts measurement bandwidth fourfold, achieving high magnetic field sensitivity.
Area of Science:
- Atomic physics
- Quantum measurement
Background:
- Alkali-metal magnetometers are crucial for sensitive magnetic field detection.
- Spin-projection noise limits magnetometer performance.
Purpose of the Study:
- To improve the measurement bandwidth of high-sensitivity alkali-metal magnetometers.
- To investigate the impact of continuous quantum nondemolition measurements on magnetometer sensitivity and bandwidth.
Main Methods:
- Experimental study of spin-projection noise.
- Implementation of continuous quantum nondemolition measurements.
- Operation in scalar mode with a 2 cm³ measurement volume.
Main Results:
- Achieved a fourfold improvement in measurement bandwidth.
- Demonstrated magnetic field sensitivity of 22 fT/Hz(1/2).
- Obtained a bandwidth of 1.9 kHz with 1% spin polarization.
Conclusions:
- Continuous quantum nondemolition measurements significantly enhance magnetometer bandwidth.
- The experimental setup is naturally backaction evading.
- Potential for sub-fT sensitivity with spin-squeezed atomic vapor.
Related Concept Videos
01:20NMR Spectrometers: Overview
NMR spectrometers consist of a strong magnet, a radiofrequency transmitter, and a detector attached to a computer console for recording spectra of samples containing NMR-active nuclei. In first-generation NMR instruments called continuous-wave spectrometers, the resonance frequencies of the nuclei are determined by frequency-sweep or field-sweep methods. The magnetic field strength is fixed and the rf signal is swept in the former, while the radiofrequency signal is fixed and the magnetic field...
01:23Atomic Nuclei: Nuclear Relaxation Processes
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis. This...
01:19Mass Analyzers: Common Types
The quadrupole mass analyzer consists of four cylindrical metal rods arranged in a diamond carrying a DC voltage and a radio-frequency AC voltage. The motion of ions through the quadrupole depends on the field strength, causing only ions of a certain m/z to resonate successfully and strike the detector at a given field strength. Though the transmission rate for these analyzers is high, the exact elemental composition of the sample is not determined because of low resolution; however, they are...
01:05Atomic Nuclei: Magnetic Resonance
The number of nuclear spins aligned in the lower energy state is slightly greater than those in the higher energy state. In the presence of an external magnetic field, as the spins precess at the Larmor frequency, the excess population results in a net magnetization oriented along the z axis. When a pulse or a short burst of radio waves at the Larmor frequency is applied along the x axis, the coupling of frequencies causes resonance and flips the nuclear spins of the excess population from the...
01:14NMR Spectrometers: Resolution and Error Correction
When magnetic nuclei in a sample achieve resonance and undergo relaxation, the signal detected in NMR is an approximately exponential free induction decay. Fourier transform of an exponential decay yields a Lorentzian peak in the frequency domain. Lorentzian peaks in an NMR spectrum are defined by their amplitude, full width at half maximum, and position, where the peak width is governed by the spin-spin relaxation time alone. In real experiments, however, the applied magnetic field is rendered...
01:11Atomic Nuclei: Larmor Precession Frequency
The earth's gravitational field produces a 'twisting force' perpendicular to the angular momentum of a spinning mass (such as a spinning top) that causes the mass to 'wobble' around the gravitational field axis in a phenomenon called precession. Similarly, the magnetic moment (μ) of a spinning nucleus precesses due to an external magnetic field directed along the z-axis. The precession of the magnetic moment vector about the magnetic field is called Larmor precession, and the angular frequency...