Learning quantum systems via out-of-time-order correlators

The complexity of NISQ

“…The excitement around NISQ algorithms has led to a plethora of new near-term algorithms targeting different applications, including quantum chemistry 3,28,[31][32][33] , machine learning 17,[34][35][36][37][38][39] , combinatorial optimization [40][41][42][43] , linear system solvers [44][45][46] , and experimental data analysis [47][48][49][50][51][52] . However, to the best of our knowledge, no existing works have rigorously examined the class of all possible NISQ algorithms and studied their inherent computational power.…”