Dynamical Phase Diagram of the REM under independent spin-flips

We study the energy landscape of the Random Energy model (REM) integrated along trajectories of the simple random walk on the hypercube. We show that the quenched cumulant generating function of the time integral of the REM energy undergoes phase transitions in the large $N$ limit for trajectories of any time extent, and identify phases distinguished by the activity and value of the time integral. This is achieved by relating the dynamical behavior to the spectral properties of Hamiltonians associated with the Quantum Random Energy Model (QREM). Of independent interest are deterministic ${\mathrm{\ell }}^p$-properties of the resolvents of such Hamiltonians, which we establish.