def circuit_to_dag(circuit):
"""Build a ``DAGCircuit`` object from a ``QuantumCircuit``.
Args:
circuit (QuantumCircuit): the input circuit.
Return:
DAGCircuit: the DAG representing the input circuit.
"""
dagcircuit = DAGCircuit()
dagcircuit.name = circuit.name
for register in circuit.qregs:
dagcircuit.add_qreg(register)
for register in circuit.cregs:
dagcircuit.add_creg(register)
# Add user gate definitions
for name, data in circuit.definitions.items():
dagcircuit.add_basis_element(name, data["n_bits"], 0, data["n_args"])
dagcircuit.add_gate_data(name, data)
# Add instructions
builtins = {
"U": ["U", 1, 0, 3],
"CX": ["CX", 2, 0, 0],
"measure": ["measure", 1, 1, 0],
"reset": ["reset", 1, 0, 0],
"barrier": ["barrier", -1, 0, 0]
}
# Add simulator instructions
simulator_instructions = {
"snapshot": ["snapshot", -1, 0, 1],
"save": ["save", -1, 0, 1],
"load": ["load", -1, 0, 1],
"noise": ["noise", -1, 0, 1]
}
for main_instruction in circuit.data:
# TODO: generate definitions and nodes for CompositeGates,
# for now simply drop their instructions into the DAG
instruction_list = []
is_composite = isinstance(main_instruction, CompositeGate)
if is_composite:
instruction_list = main_instruction.instruction_list()
else:
instruction_list.append(main_instruction)
for instruction in instruction_list:
# Add OpenQASM built-in gates on demand
if instruction.name in builtins:
dagcircuit.add_basis_element(*builtins[instruction.name])
# Add simulator extension instructions
if instruction.name in simulator_instructions:
dagcircuit.add_basis_element(
*simulator_instructions[instruction.name])
# Get arguments for classical control (if any)
if instruction.control is None:
control = None
else:
control = (instruction.control[0], instruction.control[1])
def duplicate_instruction(inst):
"""Create a fresh instruction from an input instruction."""
if inst.name == 'barrier':
params = [inst.qargs]
elif inst.name in simulator_instructions.keys():
params = inst.params + [inst.qargs] + [inst.circuit]
else:
params = inst.params + inst.qargs + inst.cargs
new_inst = inst.__class__(*params)
return new_inst
inst = duplicate_instruction(instruction)
dagcircuit.apply_operation_back(inst, inst.qargs, inst.cargs,
control)
return dagcircuit
def circuit_to_dag(circuit, expand_gates=True):
"""Build a ``DAGCircuit`` object from a ``QuantumCircuit``.
Args:
circuit (QuantumCircuit): the input circuit.
expand_gates (bool): if ``False``, none of the gates are expanded,
i.e. the gates that are defined in the circuit are included in
the DAG basis.
Return:
DAGCircuit: the DAG representing the input circuit.
"""
circuit = copy.deepcopy(circuit)
dagcircuit = DAGCircuit()
dagcircuit.name = circuit.name
for register in circuit.qregs:
dagcircuit.add_qreg(register)
for register in circuit.cregs:
dagcircuit.add_creg(register)
# Add user gate definitions
for name, data in circuit.definitions.items():
dagcircuit.add_basis_element(name, data["n_bits"], 0, data["n_args"])
dagcircuit.add_gate_data(name, data)
# Add instructions
builtins = {
"U": ["U", 1, 0, 3],
"CX": ["CX", 2, 0, 0],
"measure": ["measure", 1, 1, 0],
"reset": ["reset", 1, 0, 0],
"barrier": ["barrier", -1, 0, 0]
}
# Add simulator instructions
simulator_instructions = {
"snapshot": ["snapshot", -1, 0, 1],
"save": ["save", -1, 0, 1],
"load": ["load", -1, 0, 1],
"noise": ["noise", -1, 0, 1]
}
for main_instruction in circuit.data:
# TODO: generate definitions and nodes for CompositeGates,
# for now simply drop their instructions into the DAG
instruction_list = []
is_composite = isinstance(main_instruction, CompositeGate)
if is_composite and expand_gates:
instruction_list = main_instruction.instruction_list()
else:
instruction_list.append(main_instruction)
for instruction in instruction_list:
# Add OpenQASM built-in gates on demand
if instruction.name in builtins:
dagcircuit.add_basis_element(*builtins[instruction.name])
# Add simulator extension instructions
if instruction.name in simulator_instructions:
dagcircuit.add_basis_element(
*simulator_instructions[instruction.name])
# Get arguments for classical control (if any)
if instruction.control is None:
control = None
else:
control = (instruction.control[0], instruction.control[1])
dagcircuit.apply_operation_back(instruction, instruction.qargs,
instruction.cargs, control)
return dagcircuit