MIT researchers may have found a way to overcome a key barrier to the advent of super-fast quantum computers: amplitude spectroscopy, which provides a way to characterize quantum entities over extraordinarily broad frequency ranges.

Amplitude spectroscopy gleans information about a superconducting artificial atom by probing its response to a single, fixed frequency. This probe pushes the atom through its energy-state transitions. The atoms can be made to jump between energy bands at practically unlimited rates by adjusting the amplitude of the fixed-frequency source.

The radiation emitted by the artificial atom in response to this probe exhibits “spectroscopy diamonds” — interference patterns that serve as fingerprints of the artificial atom’s energy spectrum.