Experimental landscape

How spin-dependent fifth forces are searched for

Enter the field through the experimental architecture: what produces the possible interaction, what senses it, and which new ideas may extend the search.

01SourceGenerate or modulate the interaction
02SensorMeasure a spin-dependent response
03ConstraintLimit a potential and coupling
Research frontier

Emerging approaches to watch

Selected recent work that introduces a new experimental platform, extends a technique into a new interaction channel, or points toward substantially improved sensitivity.

Latest highlight · 2026
01

Polar diatomic molecules

Connects molecular parity-violation spectroscopy with new vector-boson-mediated electron–nucleus interactions and future cold-molecule searches.

Gaul, Cong & Budker 2026Phys. Rev. Lett. 136, 181805
Open publication ↗
Constraint data available
02

Polarized-atom interferometry

Uses internal-state differential acceleration measurements to probe spin- and velocity-dependent interactions over terrestrial length scales.

Shu et al. 2024Phys. Rev. Lett. 133, 213401
Established methods

Two routes to an experimental constraint

The directory follows the review’s distinction between dedicated source–sensor searches and complementary precision experiments.

01

Dedicated source–sensor experiments

A physical source and a spin-sensitive detector are intentionally paired to search for an exotic interaction.

SourcesMoving or rotating massesPolarized electron or nuclear spinsEarth and terrestrial matterBulk matter and cell walls
SensorsMagnetometers, comagnetometers, and vapor-cell spin sensorsSolid-state spin sensorsTorsion pendulaParticle beams
02

Complementary experiments

Existing precision measurements are interpreted as constraints on exotic spin-dependent interactions.

Established method · example

Moving-mass source with an optically polarized vapor

Linked to current metadata
Data-linked catalogue

Experiments represented in the database

Repeated curves from the same publication and method are combined into one entry. Interaction and fermion-pair tags show which constraint records are currently connected.

This literature map is growing. More publications are being classified and added. If an experiment or method is missing, please email Lei Cong (congllzu@gmail.com) with the paper and a suggested category.

A

Magnetometers and spin amplifiers

Atomic magnetometers, comagnetometers, optically polarized vapors, and spin amplifiers.

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B

Solid-state sensors

Single and ensemble NV centers, diamond sensors, and spin-mechanical devices.

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C

Mechanical sensors

Spin-polarized torsion pendula, torsion balances, and related macroscopic tests.

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D

Beam and particle sensors

Neutron-spin rotation and other dedicated particle-based source–sensor measurements.

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A

Atomic systems

Atomic spectroscopy, parity violation, fine and hyperfine structure, and collision observables.

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B

Molecular systems

Molecular spectroscopy, molecular rulers, and molecular-beam measurements.

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C

Trapped particles

Trapped ions and other confined-particle precision measurements.

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D

Additional precision systems

Complementary laboratory measurements not covered by the three bound-system groups above.

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