MCMTVChain

class MCMTVChain(gate, num_ctrl_qubits, num_target_qubits)

Bases: qiskit.circuit.library.generalized_gates.mcmt.MCMT

The MCMT implementation using the CCX V-chain.

This implementation requires ancillas but is decomposed into a much shallower circuit than the default implementation in MCMT.

Expanded Circuit:

(Source code, png, hires.png, pdf)

Examples:

>>> from qiskit.circuit.library import HGate
>>> MCMTVChain(HGate(), 3, 2).draw()

q_0: ──■────────────────────────■──

│ │

q_1: ──■────────────────────────■──

│ │

q_2: ──┼────■──────────────■────┼──

│ │ ┌───┐ │ │

q_3: ──┼────┼──┤ H ├───────┼────┼──

│ │ └─┬─┘┌───┐ │ │

q_4: ──┼────┼────┼──┤ H ├──┼────┼──

┌─┴─┐ │ │ └─┬─┘ │ ┌─┴─┐

q_5: ┤ X ├──■────┼────┼────■──┤ X ├

└───┘┌─┴─┐ │ │ ┌─┴─┐└───┘

q_6: ─────┤ X ├──■────■──┤ X ├─────

└───┘ └───┘

Create a new multi-control multi-target gate.

Parameters

• gate (Union[Gate, Callable[[QuantumCircuit, Qubit, Qubit], Instruction]]) – The gate to be applied controlled on the control qubits and applied to the target qubits. Can be either a Gate or a circuit method. If it is a callable, it will be casted to a Gate.

• num_ctrl_qubits (int) – The number of control qubits.

• num_target_qubits (int) – The number of target qubits.

Raises

• AttributeError – If the gate cannot be casted to a controlled gate.

• AttributeError – If the number of controls or targets is 0.

Methods Defined Here

inverse

Return the inverse MCMT circuit, which is itself.

Attributes

ancillas

Returns a list of ancilla bits in the order that the registers were added.

Return type

List[AncillaQubit]

calibrations

Return calibration dictionary.

The custom pulse definition of a given gate is of the form {'gate_name': {(qubits, params): schedule}}

Return type

dict

clbits

Returns a list of classical bits in the order that the registers were added.

Return type

List[Clbit]

data

Return the circuit data (instructions and context).

Returns

a list-like object containing the CircuitInstructions for each instruction.

Return type

QuantumCircuitData

extension_lib = 'include "qelib1.inc";'

global_phase

Return the global phase of the circuit in radians.

Return type

Union[ParameterExpression, float]

header = 'OPENQASM 2.0;'

instances = 2369

metadata

The user provided metadata associated with the circuit

The metadata for the circuit is a user provided dict of metadata for the circuit. It will not be used to influence the execution or operation of the circuit, but it is expected to be passed between all transforms of the circuit (ie transpilation) and that providers will associate any circuit metadata with the results it returns from execution of that circuit.

Return type

dict

num_ancilla_qubits

Return the number of ancilla qubits required.

num_ancillas

Return the number of ancilla qubits.

Return type

int

num_clbits

Return number of classical bits.

Return type

int

num_parameters

The number of parameter objects in the circuit.

Return type

int

num_qubits

Return number of qubits.

Return type

int

op_start_times

Return a list of operation start times.

This attribute is enabled once one of scheduling analysis passes runs on the quantum circuit.

Return type

List[int]

Returns

List of integers representing instruction start times. The index corresponds to the index of instruction in QuantumCircuit.data.

Raises

AttributeError – When circuit is not scheduled.

parameters

The parameters defined in the circuit.

This attribute returns the Parameter objects in the circuit sorted alphabetically. Note that parameters instantiated with a ParameterVector are still sorted numerically.

Examples

The snippet below shows that insertion order of parameters does not matter.

>>> from qiskit.circuit import QuantumCircuit, Parameter
>>> a, b, elephant = Parameter("a"), Parameter("b"), Parameter("elephant")
>>> circuit = QuantumCircuit(1)
>>> circuit.rx(b, 0)
>>> circuit.rz(elephant, 0)
>>> circuit.ry(a, 0)
>>> circuit.parameters  # sorted alphabetically!
ParameterView([Parameter(a), Parameter(b), Parameter(elephant)])

Bear in mind that alphabetical sorting might be unituitive when it comes to numbers. The literal “10” comes before “2” in strict alphabetical sorting.

>>> from qiskit.circuit import QuantumCircuit, Parameter
>>> angles = [Parameter("angle_1"), Parameter("angle_2"), Parameter("angle_10")]
>>> circuit = QuantumCircuit(1)
>>> circuit.u(*angles, 0)
>>> circuit.draw()
   ┌─────────────────────────────┐
q: ┤ U(angle_1,angle_2,angle_10) ├
   └─────────────────────────────┘
>>> circuit.parameters
ParameterView([Parameter(angle_1), Parameter(angle_10), Parameter(angle_2)])

To respect numerical sorting, a ParameterVector can be used.

>>> from qiskit.circuit import QuantumCircuit, Parameter, ParameterVector
>>> x = ParameterVector("x", 12)
>>> circuit = QuantumCircuit(1)
>>> for x_i in x:
...     circuit.rx(x_i, 0)
>>> circuit.parameters
ParameterView([
    ParameterVectorElement(x[0]), ParameterVectorElement(x[1]),
    ParameterVectorElement(x[2]), ParameterVectorElement(x[3]),
    ..., ParameterVectorElement(x[11])
])

Return type

ParameterView

Returns

The sorted Parameter objects in the circuit.

prefix = 'circuit'

qubits

Returns a list of quantum bits in the order that the registers were added.

Return type

List[Qubit]