Axion Compton Frequency to 8 ppb in 2 hours

**Table-top free-space axion electrodynamics experiment–**Infrared light from the tunable laser at 2458 nm drives a Mach-Zehnder interferometer with a dipole magnetic field in the sensing arm. A broad-band electro-optical modulator (EOM 2) modulates the phase of the light passing through the control arm to phase-lock the interferometer to the dark-fringe using a simple PID control loop driven by the 4 MHz phase modulator (EOM 1) and the lock-in amplified dark-port photodiode current (PD 1). The frequency of the light is modulated through a +/-100 MHz window to determine the light frequency where the light beam passing through the magnetic field makes axions leading to a 12 fW modulation in the dark-fringe intensity. Other components include beam-splitters (BS), mirrors (M), half-wave plate (HWP), and low-pass filter (LPF).

Science Synergy has proposed a table-top free-space axion electrodynamics experiment to determined the axion Compton frequency to 8 parts per billion (ppb) precision in 2 hours of data-taking. The proposal was prepared for the 2026 National Institute of Standards and Technology Precision Measurement Program and could begin operation as soon as 1 October 2026 subject to approval and funding availability. It is based on Science Synergy‘s September 2025 break-through in the understanding the nature of dark energy and its relation to dark matter (See Science Synergy posts Dark Energy from Dark Matter, Life Cycle of the Universe, and Science Synergy Shows How Space Grows as Time Flows) which leads to a prediction for the axion Compton frequency around 122 THz from first-principles with a precision of 65 MHz or 530 ppb.

A schematic of the proposed table-top free-space axion electrodynamics experiment is sketched in the figure. The physical principle behind the experiment, known as axion electrodynamics, is to couple the infrared electric field from a laser beam with the static magnetic field from a dipole magnet to make dark matter in the form of axions. When the frequency of the light is tuned to the Compton frequency of the axion, the photon energy in the beam converts in the magnet into the rest-mass energy of the axion, and a small but readily observable change in the light intensity can be seen.

The proposal by Science Synergy promises to determine the axion Compton frequency to 8 ppb in 2 hours of data-taking by using a dark-fringe phase-locked Mach Zehnder interferometer with a dipole magnetic field in the sensing arm. A prototype axion electrodynamics experiment with several key elements in common with the proposed Science Synergy experiment was designed, built, and demonstrated to achieve dark-port noise-equivalent power (NEP) set by the dark current in the photo-diode by Dieter Horns group at the University of Hamburg in October 2025. For the typical NEP of 200 fW/sqrt(Hz) produced at 2.46 microns by a commercially available two-stage thermoelectrically cooled InGaAs photodiode detector (Hamamatsu), this translates into a signal-to-noise ratio of five after 2 hours of data-taking for our estimated 12 fW dark-port intensity modulation from axion electrodynamics. At the axion Compton frequency around 122 THz, the typical laser line-width of 1 MHz for a commercially available tunable infrared laser at 2458 nm (Sacher Lasertechnik) then sets the 8 ppb precision of the determination.