Caltech physicists measure quantum energy ladder predicted 40 years ago

Caltech physicists have experimentally measured quantum energy levels predicted by conformal field theory for about 40 years, using laser-trapped atoms in a quantum simulator. The results confirm exact energy ratios theorized for two quantum critical points, marking the first direct observation of these predictions. Published in Nature, the experiments recreated the Ising and tricritical Ising conformal field theories using chains of up to 35 strontium atoms held by optical tweezers. Researchers developed many-body modulation spectroscopy to detect energy "rungs," finding spectra that collapsed onto universal curves matching theoretical predictions. The technique, which doesn't require knowing answers in advance, could now probe quantum systems too complex for classical computers. The team plans to expand from one-dimensional chains to two-dimensional grids, where conformal field theories are less understood.