Caltech physicists measure quantum energy ladder predicted 40 years ago

September 30, 2026 at 05:00 AM2 min

This digest was compiled by AI from multiple sources — links to the originals are below.

Caltech physicists have directly measured energy levels in synthetic quantum matter predicted by the Ising and tricritical Ising conformal field theories. The measurements were made using quantum simulators with arrays of neutral atoms held by optical tweezers. The results confirm theoretical predictions made about 40 years ago.

Key Facts

The study was published in Nature.
Researchers made the first direct measurements of energy levels predicted by the Ising and tricritical Ising conformal field theories.
The experiment used quantum simulators with arrays of neutral atoms held in place by tightly focused lasers known as optical tweezers.
The collaboration included Caltech's Manuel Endres, Jason Alicea, and theorists at Université Paris-Saclay and the Technical University of Munich.
Xiangkai Sun, a graduate student in the Endres lab, is a co-lead author of the study.

Quantum Simulator Experiment

The experiment built on technology that the Endres lab also uses for developing quantum computers. The system relies on arrays of neutral atoms held in place by tightly focused lasers known as optical tweezers. Using newly developed quantum simulator technology, the researchers made the first direct measurements of energy levels in synthetic quantum matter predicted by the Ising and tricritical Ising conformal field theories. The collaboration brought together the experimental group of Caltech's Manuel Endres, professor of physics, Alicea's theory group, and theorists at Université Paris-Saclay and the Technical University of Munich.

Conformal Field Theory Predictions

Both theories describe universal behavior that can appear when a quantum system with unusual properties such as entanglement and superposition reaches a critical point between two states, with one state being more ordered than the other. Unlike an ordinary phase transition such as water becoming steam, this transition is not caused by temperature. Instead, it arises entirely from quantum effects at temperatures close to absolute zero. At this critical point, lasers can excite the system into a sequence of specific energy states. For about 40 years, physicists have used conformal field theories to calculate how far apart those energy rungs should be.