Scalable Decoding for Measurement-Altered Criticality

Measurement-altered criticality is a phenomenon wherein partially measuring a quantum critical ground state modifies its universal correlations and entanglement. When averaging over measurement outcomes, however, such modifications manifest only in observables that are nonlinear in the density matrix and hence challenging to extract experimentally. In this talk, I will introduce decoding protocols for linear observables that leverage local measurement data to emulate nonlinear observables. Complementary analytical and numerical evidence indicates that the protocols recover universal scaling exponents for both Ising and tricritical Ising chains.  These results illuminate a path to experimental validation of aspects of measurement-altered criticality that relies on neither post-selection nor complex classical simulations of the system’s wavefunction.