def compile(circuits, backend,
config=None, basis_gates=None, coupling_map=None, initial_layout=None,
shots=1024, max_credits=10, seed=None, qobj_id=None, hpc=None,
skip_transpiler=False):
"""Compile a list of circuits into a qobj.
Args:
circuits (QuantumCircuit or list[QuantumCircuit]): circuits to compile
backend (BaseBackend or str): a backend to compile for
config (dict): dictionary of parameters (e.g. noise) used by runner
basis_gates (str): comma-separated basis gate set to compile to
coupling_map (list): coupling map (perhaps custom) to target in mapping
initial_layout (list): initial layout of qubits in mapping
shots (int): number of repetitions of each circuit, for sampling
max_credits (int): maximum credits to use
seed (int): random seed for simulators
qobj_id (int): identifier for the generated qobj
hpc (dict): HPC simulator parameters
skip_transpiler (bool): If True, bypass most of the compilation process and
creates a qobj with minimal check nor translation
Returns:
obj: the qobj to be run on the backends
"""
# pylint: disable=redefined-builtin
if isinstance(backend, str):
backend = _DEFAULT_PROVIDER.get_backend(backend)
pass_manager = None # default pass manager which executes predetermined passes
if skip_transpiler: # empty pass manager which does nothing
pass_manager = transpiler.PassManager()
return transpiler.compile(circuits, backend,
config, basis_gates, coupling_map, initial_layout,
shots, max_credits, seed, qobj_id, hpc,
pass_manager)
backend_device = IBMQ.get_backend('ibmqx4')
# 0. build circuit
from qiskit import QuantumRegister, ClassicalRegister, QuantumCircuit
q = QuantumRegister(2)
c = ClassicalRegister(2)
circ = QuantumCircuit(q, c)
circ.cx(q[0], q[1])
circ.cx(q[0], q[1])
circ.cx(q[0], q[1])
circ.cx(q[0], q[1])
circ.measure(q, c)
# draw circuit
print("orginal circuit")
print(circ.draw())
# 1. standard compile -- standard qiskit passes, when no PassManager given
from qiskit import transpiler
circuit1 = transpiler.transpile(circ, backend_device)
print("circuit after standard pass manager")
print(circuit1.draw())
# 2. custom compile -- customize PassManager to run specific circuit transformations
from qiskit.transpiler.passes import CXCancellation
pm = transpiler.PassManager()
pm.append(CXCancellation())
circuit2 = transpiler.transpile(circ, backend_device, pass_manager=pm)
print("circuit after custom pass manager")
print(circuit2.draw())