def compile_unitary(U):
"""
Takes a unitary and returns a circuit - i.e. a list of CNOTs and single qubit gates.
"""
# perform two level decomposition
two_level_unitaries = two_level_decomp(U)
assert(np.allclose(mat_mul(two_level_unitaries), U))
controlled_ops = []
# decompose each two-level unitary into fully controlled operations
for t in two_level_unitaries:
controlled_ops += two_level_to_fully_controlled(t)
assert(np.allclose(mat_mul(controlled_ops),U))
gates = []
# decompose each fully controlled operations into single qubit and CNOT gates
for c in controlled_ops:
gates += fully_controlled_to_single_cnot(c)
circ = Circuit(n)
circ.add_gates(gates)
prod = circ.evaluate()
assert(np.allclose(prod, U))
print('number of two-level: ' + str(len(two_level_unitaries)))
print('number of fully controlled ops: ' + str(len(controlled_ops)))
print('number of CNOT and single qubit gates: ' + str(len(gates)))
s = [g for g in gates if type(g) is SingleQubitGate]
c = [g for g in gates if type(g) is CNOTGate]
print('Single gates: ' + str(len(s)))
print('CNOT gates: ' + str(len(c)))
print('approximation error: ' + str(np.linalg.norm(prod-U)))
for g in gates:
if np.allclose(g.total_matrix(), np.eye(2**g.num_qubits)):
print('redundant gate')
return circ
