Generates Google Random Circuits v2 as in cz_v2.

Used in the notebooks

Used in the tutorials

See also

qubits qubit grid in which to generate the circuit.
cz_depth number of layers with CZ gates.
seed seed for the random instance.

A circuit corresponding to instance inst_{n_rows}x{ncols}{czdepth+1}{seed}

The mapping of qubits is cirq.GridQubit(j,k) -> qj*n_cols+k