circuit

Authoring types for Majorana/qubit circuits.

An ExpGate is the exponential of a generator operator -- a MajoranaOperator, PauliOperator, or FermiOperator (converted to Majorana form on construction). A bare term is rejected: only an operator carries the system num_modes / num_qubits, and its type fixes the gate's family and normalization. A Circuit is an ordered sequence of such gates, all of one family, each gate carrying one variational angle. The propagators dispatch on Circuit.family: MajoranaPropagator takes a Majorana/fermionic circuit, PauliPropagator a qubit one.