A Color Ignored by Atoms
Many quantum technologies rely on the trapping of neutral atoms by light. But that light can also shift the atoms’ energy levels, introducing operational errors. Researchers have found wavelengths at which the light does not disturb some atomic ground states. However, it has been much more difficult to identify these so-called tune-out wavelengths for excited states. Now Monika Aidelsburger and her colleagues at the Ludwig Maximilian University of Munich have experimentally determined a tune-out wavelength for the long-lived excited 3P0 state of ytterbium atoms [1].
Tune-out wavelengths are typically measured by illuminating trapped atoms with laser light whose intensity is periodically modulated. Away from a tune-out wavelength, this process heats the atoms and causes them to escape their confinement. But at a tune-out wavelength, no such heating occurs, enabling that wavelength, in principle, to be identified. One challenge is that the atoms can also escape by colliding with each other or by scattering the trapping light. For excited atomic states, this issue is greatly exacerbated because the atoms’ altered electronic configurations make them more susceptible to such processes. To avoid atom–atom collisions, the researchers worked with isolated ytterbium atoms. And to limit atom–light scattering, they laser-cooled the trapped atoms using a method that they recently developed. These advances meant that the atoms were confined sufficiently long for the team to precisely determine a 3P0 tune-out wavelength: 576.61 0.01 nm.
The researchers say that this wavelength identification could enable quantum simulations of various complex model systems. They also suggest that it unlocks a way to shuttle atoms in quantum processors without disturbing nearby atoms, a mechanism that could boost the scalability of these devices.
–Ryan Wilkinson
Ryan Wilkinson is a Corresponding Editor for Physics Magazine based in Durham, UK.
References
- T. O. Höhn et al., “Determining the 3P0 excited-state tune-out wavelength of 174Yb in a triple-magic lattice,” PRX Quantum 7, 010303 (2026).