Faster cooling on the same hardware
The experiment used one calcium-40 ion held about 50 micrometers above a silicon surface-electrode trap chip. The researchers tested a standing-wave approach to electromagnetically induced transparency, or EIT, cooling against a conventional running-wave EIT scheme.
In the team's arXiv preprint, the standing-wave method brought the target radial motional mode to a mean phonon occupancy of about 0.05 in roughly 150 microseconds. The running-wave method, tested on the same hardware, reached about 0.088 phonons after 500 microseconds.
The technique also cooled all three measured motional modes simultaneously across a frequency range of approximately 5 megahertz. Conventional methods often address different types of motion through separate cooling operations.
Testing long-standing predictions
The authors describe their work as the first experimental demonstration of EIT ground-state cooling with a standing-wave "probe" beam and the atom positioned at a node. They say the result verifies a prediction made by Cirac and colleagues in 1992.
In a separate demonstration, the team used Doppler cooling to cool a trapped ion at a standing-wave node below the conventional Doppler limit, experimentally confirming another long-standing theoretical prediction.
According to Cornell Chronicle, the findings appeared in PRX Quantum on Nov. 9, 2026. The research was led by Karan Mehta, an assistant professor of electrical and computer engineering in Cornell's Duffield College of Engineering.
Chip fabrication and research support
A collaboration with ETH Zurich arranged commercial fabrication of the ion-trap chips in the Netherlands. Cornell facilities, including the Cornell NanoScale Science and Technology Facility, handled packaging and preparation for the experiments.
Funding came from the National Science Foundation, the Army Research Office and the Alfred P. Sloan Foundation.
