qiskit/transpiler/passes/optimize_1q_gates.py
def run(self, dag):
        """Return a new circuit that has been optimized."""
        runs = dag.collect_runs(["u1", "u2", "u3", "id"])
        runs = _split_runs_on_parameters(runs)
        for run in runs:
            right_name = "u1"
            right_parameters = (0, 0, 0)  # (theta, phi, lambda)

            for current_node in run:
                left_name = current_node.name
                if (current_node.condition is not None
                        or len(current_node.qargs) != 1
                        or left_name not in ["u1", "u2", "u3", "id"]):
                    raise TranspilerError("internal error")
                if left_name == "u1":
                    left_parameters = (0, 0, current_node.op.params[0])
                elif left_name == "u2":
                    left_parameters = (np.pi / 2, current_node.op.params[0],
                                       current_node.op.params[1])
                elif left_name == "u3":
                    left_parameters = tuple(current_node.op.params)
                else:
                    left_name = "u1"  # replace id with u1
                    left_parameters = (0, 0, 0)
                # If there are any sympy objects coming from the gate convert
                # to numpy.
                left_parameters = tuple([float(x) for x in left_parameters])
                # Compose gates
                name_tuple = (left_name, right_name)
                if name_tuple == ("u1", "u1"):
                    # u1(lambda1) * u1(lambda2) = u1(lambda1 + lambda2)
                    right_parameters = (0, 0, right_parameters[2] +
                                        left_parameters[2])
                elif name_tuple == ("u1", "u2"):
                    # u1(lambda1) * u2(phi2, lambda2) = u2(phi2 + lambda1, lambda2)
                    right_parameters = (np.pi / 2, right_parameters[1] +
                                        left_parameters[2], right_parameters[2])
                elif name_tuple == ("u2", "u1"):
                    # u2(phi1, lambda1) * u1(lambda2) = u2(phi1, lambda1 + lambda2)
                    right_name = "u2"
                    right_parameters = (np.pi / 2, left_parameters[1],
                                        right_parameters[2] + left_parameters[2])
                elif name_tuple == ("u1", "u3"):
                    # u1(lambda1) * u3(theta2, phi2, lambda2) =
                    #     u3(theta2, phi2 + lambda1, lambda2)
                    right_parameters = (right_parameters[0], right_parameters[1] +
                                        left_parameters[2], right_parameters[2])
                elif name_tuple == ("u3", "u1"):
                    # u3(theta1, phi1, lambda1) * u1(lambda2) =
                    #     u3(theta1, phi1, lambda1 + lambda2)
                    right_name = "u3"
                    right_parameters = (left_parameters[0], left_parameters[1],
                                        right_parameters[2] + left_parameters[2])
                elif name_tuple == ("u2", "u2"):
                    # Using Ry(pi/2).Rz(2*lambda).Ry(pi/2) =
                    #    Rz(pi/2).Ry(pi-2*lambda).Rz(pi/2),
                    # u2(phi1, lambda1) * u2(phi2, lambda2) =
                    #    u3(pi - lambda1 - phi2, phi1 + pi/2, lambda2 + pi/2)
                    right_name = "u3"
                    right_parameters = (np.pi - left_parameters[2] -
                                        right_parameters[1], left_parameters[1] +
                                        np.pi / 2, right_parameters[2] +
                                        np.pi / 2)
                elif name_tuple[1] == "nop":
                    right_name = left_name
                    right_parameters = left_parameters
                else:
                    # For composing u3's or u2's with u3's, use
                    # u2(phi, lambda) = u3(pi/2, phi, lambda)
                    # together with the qiskit.mapper.compose_u3 method.
                    right_name = "u3"
                    # Evaluate the symbolic expressions for efficiency
                    right_parameters = Optimize1qGates.compose_u3(left_parameters[0],
                                                                  left_parameters[1],
                                                                  left_parameters[2],
                                                                  right_parameters[0],
                                                                  right_parameters[1],
                                                                  right_parameters[2])
                    # Why evalf()? This program:
                    #   OPENQASM 2.0;
                    #   include "qelib1.inc";
                    #   qreg q[2];
                    #   creg c[2];
                    #   u3(0.518016983430947*pi,1.37051598592907*pi,1.36816383603222*pi) q[0];
                    #   u3(1.69867232277986*pi,0.371448347747471*pi,0.461117217930936*pi) q[0];
                    #   u3(0.294319836336836*pi,0.450325871124225*pi,1.46804720442555*pi) q[0];
                    #   measure q -> c;
                    # took >630 seconds (did not complete) to optimize without
                    # calling evalf() at all, 19 seconds to optimize calling
                    # evalf() AFTER compose_u3, and 1 second to optimize
                    # calling evalf() BEFORE compose_u3.
                # 1. Here down, when we simplify, we add f(theta) to lambda to
                # correct the global phase when f(theta) is 2*pi. This isn't
                # necessary but the other steps preserve the global phase, so
                # we continue in that manner.
                # 2. The final step will remove Z rotations by 2*pi.
                # 3. Note that is_zero is true only if the expression is exactly
                # zero. If the input expressions have already been evaluated
                # then these final simplifications will not occur.
                # TODO After we refactor, we should have separate passes for
                # exact and approximate rewriting.

                # Y rotation is 0 mod 2*pi, so the gate is a u1
                if np.mod(right_parameters[0], (2 * np.pi)) == 0 \
                        and right_name != "u1":
                    right_name = "u1"
                    right_parameters = (0, 0, right_parameters[1] +
                                        right_parameters[2] +
                                        right_parameters[0])
                # Y rotation is pi/2 or -pi/2 mod 2*pi, so the gate is a u2
                if right_name == "u3":
                    # theta = pi/2 + 2*k*pi
                    if np.mod((right_parameters[0] - np.pi / 2), (2 * np.pi)) == 0:
                        right_name = "u2"
                        right_parameters = (np.pi / 2, right_parameters[1],
                                            right_parameters[2] +
                                            (right_parameters[0] - np.pi / 2))
                    # theta = -pi/2 + 2*k*pi
                    if np.mod((right_parameters[0] + np.pi / 2), (2 * np.pi)) == 0:
                        right_name = "u2"
                        right_parameters = (np.pi / 2, right_parameters[1] +
                                            np.pi, right_parameters[2] -
                                            np.pi + (right_parameters[0] +
                                                     np.pi / 2))
                # u1 and lambda is 0 mod 2*pi so gate is nop (up to a global phase)
                if right_name == "u1" and np.mod(right_parameters[2], (2 * np.pi)) == 0:
                    right_name = "nop"

            # Replace the the first node in the run with a dummy DAG which contains a dummy
            # qubit. The name is irrelevant, because substitute_node_with_dag will take care of
            # putting it in the right place.
            run_qarg = (QuantumRegister(1, 'q'), 0)
            new_op = Gate(name="", num_qubits=1, params=[])
            if right_name == "u1":
                new_op = U1Gate(right_parameters[2])
            if right_name == "u2":
                new_op = U2Gate(right_parameters[1], right_parameters[2])
            if right_name == "u3":
                new_op = U3Gate(*right_parameters)

            if right_name != 'nop':
                new_dag = DAGCircuit()
                new_dag.add_qreg(run_qarg[0])
                new_dag.apply_operation_back(new_op, [run_qarg], [])
                dag.substitute_node_with_dag(run[0], new_dag)

            # Delete the other nodes in the run
            for current_node in run[1:]:
                dag.remove_op_node(current_node)
            if right_name == "nop":
                dag.remove_op_node(run[0])

        return dag
def run(self, dag):
        """Return a new circuit that has been optimized."""
        runs = dag.collect_runs(["u1", "u2", "u3", "id"])
        runs = _split_runs_on_parameters(runs)
        for run in runs:
            right_name = "u1"
            right_parameters = (0, 0, 0)  # (theta, phi, lambda)

            for current_node in run:
                left_name = current_node.name
                if (current_node.condition is not None
                        or len(current_node.qargs) != 1
                        or left_name not in ["u1", "u2", "u3", "id"]):
                    raise TranspilerError("internal error")
                if left_name == "u1":
                    left_parameters = (0, 0, current_node.op.params[0])
                elif left_name == "u2":
                    left_parameters = (np.pi / 2, current_node.op.params[0],
                                       current_node.op.params[1])
                elif left_name == "u3":
                    left_parameters = tuple(current_node.op.params)
                else:
                    left_name = "u1"  # replace id with u1
                    left_parameters = (0, 0, 0)
                # If there are any sympy objects coming from the gate convert
                # to numpy.
                left_parameters = tuple([float(x) for x in left_parameters])
                # Compose gates
                name_tuple = (left_name, right_name)
                if name_tuple == ("u1", "u1"):
                    # u1(lambda1) * u1(lambda2) = u1(lambda1 + lambda2)
                    right_parameters = (0, 0, right_parameters[2] +
                                        left_parameters[2])
                elif name_tuple == ("u1", "u2"):
                    # u1(lambda1) * u2(phi2, lambda2) = u2(phi2 + lambda1, lambda2)
                    right_parameters = (np.pi / 2, right_parameters[1] +
                                        left_parameters[2], right_parameters[2])
                elif name_tuple == ("u2", "u1"):
                    # u2(phi1, lambda1) * u1(lambda2) = u2(phi1, lambda1 + lambda2)
                    right_name = "u2"
                    right_parameters = (np.pi / 2, left_parameters[1],
                                        right_parameters[2] + left_parameters[2])
                elif name_tuple == ("u1", "u3"):
                    # u1(lambda1) * u3(theta2, phi2, lambda2) =
                    #     u3(theta2, phi2 + lambda1, lambda2)
                    right_parameters = (right_parameters[0], right_parameters[1] +
                                        left_parameters[2], right_parameters[2])
                elif name_tuple == ("u3", "u1"):
                    # u3(theta1, phi1, lambda1) * u1(lambda2) =
                    #     u3(theta1, phi1, lambda1 + lambda2)
                    right_name = "u3"
                    right_parameters = (left_parameters[0], left_parameters[1],
                                        right_parameters[2] + left_parameters[2])
                elif name_tuple == ("u2", "u2"):
                    # Using Ry(pi/2).Rz(2*lambda).Ry(pi/2) =
                    #    Rz(pi/2).Ry(pi-2*lambda).Rz(pi/2),
                    # u2(phi1, lambda1) * u2(phi2, lambda2) =
                    #    u3(pi - lambda1 - phi2, phi1 + pi/2, lambda2 + pi/2)
                    right_name = "u3"
                    right_parameters = (np.pi - left_parameters[2] -
                                        right_parameters[1], left_parameters[1] +
                                        np.pi / 2, right_parameters[2] +
                                        np.pi / 2)
                elif name_tuple[1] == "nop":
                    right_name = left_name
                    right_parameters = left_parameters
                else:
                    # For composing u3's or u2's with u3's, use
                    # u2(phi, lambda) = u3(pi/2, phi, lambda)
                    # together with the qiskit.mapper.compose_u3 method.
                    right_name = "u3"
                    # Evaluate the symbolic expressions for efficiency
                    right_parameters = Optimize1qGates.compose_u3(left_parameters[0],
                                                                  left_parameters[1],
                                                                  left_parameters[2],
                                                                  right_parameters[0],
                                                                  right_parameters[1],
                                                                  right_parameters[2])
                    # Why evalf()? This program:
                    #   OPENQASM 2.0;
                    #   include "qelib1.inc";
                    #   qreg q[2];
                    #   creg c[2];
                    #   u3(0.518016983430947*pi,1.37051598592907*pi,1.36816383603222*pi) q[0];
                    #   u3(1.69867232277986*pi,0.371448347747471*pi,0.461117217930936*pi) q[0];
                    #   u3(0.294319836336836*pi,0.450325871124225*pi,1.46804720442555*pi) q[0];
                    #   measure q -> c;
                    # took >630 seconds (did not complete) to optimize without
                    # calling evalf() at all, 19 seconds to optimize calling
                    # evalf() AFTER compose_u3, and 1 second to optimize
                    # calling evalf() BEFORE compose_u3.
                # 1. Here down, when we simplify, we add f(theta) to lambda to
                # correct the global phase when f(theta) is 2*pi. This isn't
                # necessary but the other steps preserve the global phase, so
                # we continue in that manner.
                # 2. The final step will remove Z rotations by 2*pi.
                # 3. Note that is_zero is true only if the expression is exactly
                # zero. If the input expressions have already been evaluated
                # then these final simplifications will not occur.
                # TODO After we refactor, we should have separate passes for
                # exact and approximate rewriting.

                # Y rotation is 0 mod 2*pi, so the gate is a u1
                if np.mod(right_parameters[0], (2 * np.pi)) == 0 \
                        and right_name != "u1":
                    right_name = "u1"
                    right_parameters = (0, 0, right_parameters[1] +
                                        right_parameters[2] +
                                        right_parameters[0])
                # Y rotation is pi/2 or -pi/2 mod 2*pi, so the gate is a u2
                if right_name == "u3":
                    # theta = pi/2 + 2*k*pi
                    if np.mod((right_parameters[0] - np.pi / 2), (2 * np.pi)) == 0:
                        right_name = "u2"
                        right_parameters = (np.pi / 2, right_parameters[1],
                                            right_parameters[2] +
                                            (right_parameters[0] - np.pi / 2))
                    # theta = -pi/2 + 2*k*pi
                    if np.mod((right_parameters[0] + np.pi / 2), (2 * np.pi)) == 0:
                        right_name = "u2"
                        right_parameters = (np.pi / 2, right_parameters[1] +
                                            np.pi, right_parameters[2] -
                                            np.pi + (right_parameters[0] +
                                                     np.pi / 2))
                # u1 and lambda is 0 mod 2*pi so gate is nop (up to a global phase)
                if right_name == "u1" and np.mod(right_parameters[2], (2 * np.pi)) == 0:
                    right_name = "nop"

            # Replace the the first node in the run with a dummy DAG which contains a dummy
            # qubit. The name is irrelevant, because substitute_node_with_dag will take care of
            # putting it in the right place.
            run_qarg = (QuantumRegister(1, 'q'), 0)
            new_op = Gate(name="", num_qubits=1, params=[])
            if right_name == "u1":
                new_op = U1Gate(right_parameters[2])
            if right_name == "u2":
                new_op = U2Gate(right_parameters[1], right_parameters[2])
            if right_name == "u3":
                new_op = U3Gate(*right_parameters)

            if right_name != 'nop':
                new_dag = DAGCircuit()
                new_dag.add_qreg(run_qarg[0])
                new_dag.apply_operation_back(new_op, [run_qarg], [])
                dag.substitute_node_with_dag(run[0], new_dag)

            # Delete the other nodes in the run
            for current_node in run[1:]:
                dag.remove_op_node(current_node)
            if right_name == "nop":
                dag.remove_op_node(run[0])

        return dag
Return a new circuit that has been optimized.