Fast classical simulation of evidence for the utility of quantum
  computing before fault tolerance
We show that a classical algorithm based on sparse Pauli dynamics can
efficiently simulate quantum circuits studied in a recent experiment on 127
qubits of IBM's Eagle processor [Nature 618, 500 (2023)]. Our classical
simulations on a single core of a laptop are orders of magnitude faster than
the reported walltime of the quantum simulations, as well as faster than the
estimated quantum hardware runtime without classical processing, and are in
good agreement with the zero-noise extrapolated experimental results.
Tomislav Begušić Garnet Kin-Lic Chan