74 research outputs found
A Precessing Ferromagnetic Needle Magnetometer
A ferromagnetic needle is predicted to precess about the magnetic field axis
at a Larmor frequency under conditions where its intrinsic spin
dominates over its rotational angular momentum, ( is
the moment of inertia of the needle about the precession axis and is the
number of polarized spins in the needle). In this regime the needle behaves as
a gyroscope with spin maintained along the easy axis of the needle by
the crystalline and shape anisotropy. A precessing ferromagnetic needle is a
correlated system of spins which can be used to measure magnetic fields for
long times. In principle, by taking advantage of rapid averaging of quantum
uncertainty, the sensitivity of a precessing needle magnetometer can far
surpass that of magnetometers based on spin precession of atoms in the gas
phase. Under conditions where noise from coupling to the environment is
subdominant, the scaling with measurement time of the quantum- and
detection-limited magnetometric sensitivity is . The phenomenon of
ferromagnetic needle precession may be of particular interest for precision
measurements testing fundamental physics.Comment: Main text: 6 pages, 2 figures; Supplementary material: 3 pages, 1
figur
Relaxation of atomic polarization in paraffin-coated cesium vapor cells
The relaxation of atomic polarization in buffer-gas-free, paraffin-coated
cesium vapor cells is studied using a variation on Franzen's technique of
``relaxation in the dark'' [Franzen, Phys. Rev. {\bf 115}, 850 (1959)]. In the
present experiment, narrow-band, circularly polarized pump light, resonant with
the Cs D2 transition, orients atoms along a longitudinal magnetic field, and
time-dependent optical rotation of linearly polarized probe light is measured
to determine the relaxation rates of the atomic orientation of a particular
hyperfine level. The change in relaxation rates during light-induced atomic
desorption (LIAD) is studied. No significant change in the spin relaxation rate
during LIAD is found beyond that expected from the faster rate of spin-exchange
collisions due to the increase in Cs density.Comment: 14 pages, 14 figure
Quantum sensor networks as exotic field telescopes for multi-messenger astronomy
Multi-messenger astronomy, the coordinated observation of different classes
of signals originating from the same astrophysical event, provides a wealth of
information about astrophysical processes with far-reaching implications. So
far, the focus of multi-messenger astronomy has been the search for
conventional signals from known fundamental forces and standard model
particles, like gravitational waves (GW). In addition to these known effects,
quantum sensor networks could be used to search for astrophysical signals
predicted by beyond-standard-model (BSM) theories. Exotic bosonic fields are
ubiquitous features of BSM theories and appear while seeking to understand the
nature of dark matter and dark energy and solve the hierarchy and strong CP
problems. We consider the case where high-energy astrophysical events could
produce intense bursts of exotic low-mass fields (ELFs). We propose to expand
the toolbox of multi-messenger astronomy to include networks of precision
quantum sensors that by design are shielded from or insensitive to conventional
standard-model physics signals. We estimate ELF signal amplitudes, delays,
rates, and distances of GW sources to which global networks of atomic
magnetometers and atomic clocks could be sensitive. We find that, indeed, such
precision quantum sensor networks can function as ELF telescopes to detect
signals from sources generating ELF bursts of sufficient intensity. Thus ELFs,
if they exist, could act as additional messengers for astrophysical events.Comment: 19 pages, 5 figure
A network of precision gravimeters as a detector of matter with feeble nongravitational coupling
Hidden matter that interacts only gravitationally would oscillate at
characteristic frequencies when trapped inside of Earth. For small oscillations
near the center of the Earth, these frequencies are around 300 Hz.
Additionally, signatures at higher harmonics would appear because of the
non-uniformity of Earth's density. In this work, we use data from a global
network of gravimeters of the International Geodynamics and Earth Tide Service
(IGETS) to look for these hypothetical trapped objects. We find no evidence for
such objects with masses on the order of 10 kg or greater with an
oscillation amplitude of 0.1 . It may be possible to improve the
sensitivity of the search by several orders of magnitude via better
understanding of the terrestrial noise sources and more advanced data analysis
Universal determination of comagnetometer response to spin couplings
We propose and demonstrate a general method to calibrate the
frequency-dependent response of self-compensating noble-gas-alkali-metal
comagnetometers to arbitrary spin perturbations. This includes magnetic and
nonmagnetic perturbations like rotations and exotic spin interactions. The
method is based on a fit of the magnetic field response to an analytical model.
The frequency-dependent response of the comagnetometer to arbitrary spin
perturbations can be inferred using the fit parameters. We demonstrate the
effectiveness of this method by comparing the inferred rotation response to an
experimental measurement of the rotation response. Our results show that
experiments relying on zero-frequency calibration of the comagnetometer
response can over- or under-estimate the comagnetometer sensitivity by orders
of magnitude over a wide frequency range. Moreover, this discrepancy
accumulates over time as operational parameters tend to drift during
comagnetometer operation. The demonstrated calibration protocol enables
accurate prediction and control of comagnetometer sensitivity to, for example,
ultralight bosonic dark-matter fields coupling to electron or nuclear spins as
well as accurate monitoring and control of the relevant system parameters
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