117 research outputs found
Spectral signatures of many-body localization with interacting photons
Statistical mechanics is founded on the assumption that a system can reach
thermal equilibrium, regardless of the starting state. Interactions between
particles facilitate thermalization, but, can interacting systems always
equilibrate regardless of parameter values\,? The energy spectrum of a system
can answer this question and reveal the nature of the underlying phases.
However, most experimental techniques only indirectly probe the many-body
energy spectrum. Using a chain of nine superconducting qubits, we implement a
novel technique for directly resolving the energy levels of interacting
photons. We benchmark this method by capturing the intricate energy spectrum
predicted for 2D electrons in a magnetic field, the Hofstadter butterfly. By
increasing disorder, the spatial extent of energy eigenstates at the edge of
the energy band shrink, suggesting the formation of a mobility edge. At strong
disorder, the energy levels cease to repel one another and their statistics
approaches a Poisson distribution - the hallmark of transition from the
thermalized to the many-body localized phase. Our work introduces a new
many-body spectroscopy technique to study quantum phases of matter
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