Rydberg chain reveals energy ratios of quantum field theories

Researchers have directly observed energy excitation spectra characteristic of underlying field theories using a variably tuned Rydberg chain at quantum phase transitions. The work recovers universal energy ratios characteristic of the underlying field theories, offering a new method for examining emergent universal properties of systems undergoing these transitions. Specifically, the team distinguished excitation parities with local control, and in a tricritical Ising chain, induced transitions between distinct spectra by changing boundary conditions. This modulation technique also provides a method for diagnosing previously unknown universality classes in future experiments. A ratio of energy levels characteristic of conformal field theory (CFT) was recovered, a result achieved using a chain…