Atoms in a beam travel at different speeds, like runners on a track. A regular laser pulse only pushes those moving at one speed, but the new one acts like a coach giving commands to the whole group at once. This approach involves more atoms in the measurement.
In an experiment with a Mach-Zehnder atom interferometer, the velocity spread was 17 times larger than the laser linewidth. The new method raised the fringe contrast from 5.9% to 15.1% — the picture became sharper and the data more reliable.
Spectral control of the laser is like tuning a radio to several frequencies at once to catch all stations simultaneously. This method can now be applied in quantum sensors where atoms move at different speeds and some were previously lost.
The velocity spread of atoms in the beam was 17 times larger than the laser pulse width — as if a coach were shouting commands to both sprinters and marathon runners.