qiskit.circuit.ControlledGate

class ControlledGate(name, num_qubits, params, label=None, num_ctrl_qubits=1, definition=None, ctrl_state=None, base_gate=None)

Controlled unitary gate.

Create a new ControlledGate. In the new gate the first num_ctrl_qubits of the gate are the controls.

Parameter

• name (str) – The name of the gate.

• num_qubits (int) – The number of qubits the gate acts on.

• params (List) – A list of parameters for the gate.

• label (Optional[str]) – An optional label for the gate.

• num_ctrl_qubits (Optional[int]) – Number of control qubits.

• definition (Optional[QuantumCircuit]) – A list of gate rules for implementing this gate. The elements of the list are tuples of (Gate(), [qubit_list], [clbit_list]).

• ctrl_state (Union[int, str, None]) – The control state in decimal or as a bitstring (e.g. ‚111‘). If specified as a bitstring the length must equal num_ctrl_qubits, MSB on left. If None, use 2**num_ctrl_qubits-1.

• base_gate (Optional[Gate]) – Gate object to be controlled.

Verursacht

• CircuitError – If num_ctrl_qubits >= num_qubits.

• CircuitError – ctrl_state < 0 or ctrl_state > 2**num_ctrl_qubits.

Examples:

Create a controlled standard gate and apply it to a circuit.

from qiskit import QuantumCircuit, QuantumRegister
from qiskit.circuit.library.standard_gates import HGate

qr = QuantumRegister(3)
qc = QuantumCircuit(qr)
c3h_gate = HGate().control(2)
qc.append(c3h_gate, qr)
qc.draw()

           
q0_0: ──■──
        │  
q0_1: ──■──
      ┌─┴─┐
q0_2: ┤ H ├
      └───┘

Create a controlled custom gate and apply it to a circuit.

from qiskit import QuantumCircuit, QuantumRegister
from qiskit.circuit.library.standard_gates import HGate

qc1 = QuantumCircuit(2)
qc1.x(0)
qc1.h(1)
custom = qc1.to_gate().control(2)

qc2 = QuantumCircuit(4)
qc2.append(custom, [0, 3, 1, 2])
qc2.draw()

                   
q_0: ──────■───────
     ┌─────┴──────┐
q_1: ┤0           ├
     │  circuit14 │
q_2: ┤1           ├
     └─────┬──────┘
q_3: ──────■───────
                   

__init__(name, num_qubits, params, label=None, num_ctrl_qubits=1, definition=None, ctrl_state=None, base_gate=None)

Create a new ControlledGate. In the new gate the first num_ctrl_qubits of the gate are the controls.

Parameter

• name (str) – The name of the gate.

• num_qubits (int) – The number of qubits the gate acts on.

• params (List) – A list of parameters for the gate.

• label (Optional[str]) – An optional label for the gate.

• num_ctrl_qubits (Optional[int]) – Number of control qubits.

• definition (Optional[QuantumCircuit]) – A list of gate rules for implementing this gate. The elements of the list are tuples of (Gate(), [qubit_list], [clbit_list]).

• ctrl_state (Union[int, str, None]) – The control state in decimal or as a bitstring (e.g. ‚111‘). If specified as a bitstring the length must equal num_ctrl_qubits, MSB on left. If None, use 2**num_ctrl_qubits-1.

• base_gate (Optional[Gate]) – Gate object to be controlled.

Verursacht

• CircuitError – If num_ctrl_qubits >= num_qubits.

• CircuitError – ctrl_state < 0 or ctrl_state > 2**num_ctrl_qubits.

Examples:

Create a controlled standard gate and apply it to a circuit.

from qiskit import QuantumCircuit, QuantumRegister
from qiskit.circuit.library.standard_gates import HGate

qr = QuantumRegister(3)
qc = QuantumCircuit(qr)
c3h_gate = HGate().control(2)
qc.append(c3h_gate, qr)
qc.draw()

           
q1_0: ──■──
        │  
q1_1: ──■──
      ┌─┴─┐
q1_2: ┤ H ├
      └───┘

Create a controlled custom gate and apply it to a circuit.

from qiskit import QuantumCircuit, QuantumRegister
from qiskit.circuit.library.standard_gates import HGate

qc1 = QuantumCircuit(2)
qc1.x(0)
qc1.h(1)
custom = qc1.to_gate().control(2)

qc2 = QuantumCircuit(4)
qc2.append(custom, [0, 3, 1, 2])
qc2.draw()

                   
q_0: ──────■───────
     ┌─────┴──────┐
q_1: ┤0           ├
     │  circuit31 │
q_2: ┤1           ├
     └─────┬──────┘
q_3: ──────■───────
                   

Methods

__init__(name, num_qubits, params[, label, …])	Create a new ControlledGate.
add_decomposition(decomposition)	Add a decomposition of the instruction to the SessionEquivalenceLibrary.
assemble()	Assemble a QasmQobjInstruction
broadcast_arguments(qargs, cargs)	Validation and handling of the arguments and its relationship.
c_if(classical, val)	Add classical condition on register classical and value val.
control([num_ctrl_qubits, label, ctrl_state])	Return controlled version of gate.
copy([name])	Copy of the instruction.
inverse()	Invert this gate by calling inverse on the base gate.
is_parameterized()	Return True .IFF.
mirror()	DEPRECATED: use instruction.reverse_ops().
power(exponent)	Creates a unitary gate as gate^exponent.
qasm()	Return a default OpenQASM string for the instruction.
repeat(n)	Creates an instruction with gate repeated n amount of times.
reverse_ops()	For a composite instruction, reverse the order of sub-instructions.
to_matrix()	Return a Numpy.array for the gate unitary matrix.
validate_parameter(parameter)	Gate parameters should be int, float, or ParameterExpression

Attributes

ctrl_state	Return the control state of the gate as a decimal integer.
decompositions	Get the decompositions of the instruction from the SessionEquivalenceLibrary.
definition	Return definition in terms of other basic gates.
duration	Get the duration.
label	Return gate label
num_ctrl_qubits	Get number of control qubits.
params	Get parameters from base_gate.
unit	Get the time unit of duration.

add_decomposition(decomposition)

Add a decomposition of the instruction to the SessionEquivalenceLibrary.

assemble()

Assemble a QasmQobjInstruction

Rückgabetyp

Instruction

broadcast_arguments(qargs, cargs)

Validation and handling of the arguments and its relationship.

For example, cx([q[0],q[1]], q[2]) means cx(q[0], q[2]); cx(q[1], q[2]). This method yields the arguments in the right grouping. In the given example:

in: [[q[0],q[1]], q[2]],[]
outs: [q[0], q[2]], []
      [q[1], q[2]], []

The general broadcasting rules are:

• If len(qargs) == 1:

  [q[0], q[1]] -> [q[0]],[q[1]]
  

• If len(qargs) == 2:

  [[q[0], q[1]], [r[0], r[1]]] -> [q[0], r[0]], [q[1], r[1]]
  [[q[0]], [r[0], r[1]]]       -> [q[0], r[0]], [q[0], r[1]]
  [[q[0], q[1]], [r[0]]]       -> [q[0], r[0]], [q[1], r[0]]
  

• If len(qargs) >= 3:

  [q[0], q[1]], [r[0], r[1]],  ...] -> [q[0], r[0], ...], [q[1], r[1], ...]
  

Parameter

• qargs (List) – List of quantum bit arguments.

• cargs (List) – List of classical bit arguments.

Rückgabetyp

Tuple[List, List]

Rückgabe

A tuple with single arguments.

Verursacht

CircuitError – If the input is not valid. For example, the number of arguments does not match the gate expectation.

c_if(classical, val)

Add classical condition on register classical and value val.

control(num_ctrl_qubits=1, label=None, ctrl_state=None)

Return controlled version of gate. See ControlledGate for usage.

Parameter

• num_ctrl_qubits (Optional[int]) – number of controls to add to gate (default=1)

• label (Optional[str]) – optional gate label

• ctrl_state (Union[int, str, None]) – The control state in decimal or as a bitstring (e.g. ‚111‘). If None, use 2**num_ctrl_qubits-1.

Rückgabe

Controlled version of gate. This default algorithm uses num_ctrl_qubits-1 ancillae qubits so returns a gate of size num_qubits + 2*num_ctrl_qubits - 1.

Rückgabetyp

qiskit.circuit.ControlledGate

Verursacht

QiskitError – unrecognized mode or invalid ctrl_state

copy(name=None)

Copy of the instruction.

Parameter

name (str) – name to be given to the copied circuit, if None then the name stays the same.

Rückgabe

a copy of the current instruction, with the name

updated if it was provided

Rückgabetyp

qiskit.circuit.Instruction

property ctrl_state

Return the control state of the gate as a decimal integer.

Rückgabetyp

int

property decompositions

Get the decompositions of the instruction from the SessionEquivalenceLibrary.

property definition

Return definition in terms of other basic gates. If the gate has open controls, as determined from self.ctrl_state, the returned definition is conjugated with X without changing the internal _definition.

Rückgabetyp

List

property duration

Get the duration.

inverse()

Invert this gate by calling inverse on the base gate.

Rückgabetyp

ControlledGate

is_parameterized()

Return True .IFF. instruction is parameterized else False

property label

Return gate label

Rückgabetyp

str

mirror()

DEPRECATED: use instruction.reverse_ops().

Rückgabe

a new instruction with sub-instructions

reversed.

Rückgabetyp

qiskit.circuit.Instruction

property num_ctrl_qubits

Get number of control qubits.

Rückgabe

The number of control qubits for the gate.

Rückgabetyp

int

property params

Get parameters from base_gate.

Rückgabe

List of gate parameters.

Rückgabetyp

list

Verursacht

CircuitError – Controlled gate does not define a base gate

power(exponent)

Creates a unitary gate as gate^exponent.

Parameter

exponent (float) – Gate^exponent

Rückgabe

To which to_matrix is self.to_matrix^exponent.

Rückgabetyp

qiskit.extensions.UnitaryGate

Verursacht

CircuitError – If Gate is not unitary

qasm()

Return a default OpenQASM string for the instruction.

Derived instructions may override this to print in a different format (e.g. measure q[0] -> c[0];).

repeat(n)

Creates an instruction with gate repeated n amount of times.

Parameter

n (int) – Number of times to repeat the instruction

Rückgabe

Containing the definition.

Rückgabetyp

qiskit.circuit.Instruction

Verursacht

CircuitError – If n < 1.

reverse_ops()

For a composite instruction, reverse the order of sub-instructions.

This is done by recursively reversing all sub-instructions. It does not invert any gate.

Rückgabe

a new instruction with

sub-instructions reversed.

Rückgabetyp

qiskit.circuit.Instruction

to_matrix()

Return a Numpy.array for the gate unitary matrix.

Verursacht

CircuitError – If a Gate subclass does not implement this method an exception will be raised when this base class method is called.

Rückgabetyp

ndarray

property unit

Get the time unit of duration.

validate_parameter(parameter)

Gate parameters should be int, float, or ParameterExpression