CXGate
class CXGate(label=None, ctrl_state=None)
Bases: qiskit.circuit.controlledgate.ControlledGate
Controlled-X gate.
Circuit symbol:
q_0: ──■──
┌─┴─┐
q_1: ┤ X ├
└───┘Matrix representation:
In Qiskit’s convention, higher qubit indices are more significant (little endian convention). In many textbooks, controlled gates are presented with the assumption of more significant qubits as control, which in our case would be q_1. Thus a textbook matrix for this gate will be:
┌───┐
q_0: ┤ X ├
└─┬─┘
q_1: ──■──In the computational basis, this gate flips the target qubit if the control qubit is in the state. In this sense it is similar to a classical XOR gate.
Create new CX gate.
Methods Defined Here
control
CXGate.control(num_ctrl_qubits=1, label=None, ctrl_state=None)
Return a controlled-X gate with more control lines.
Parameters
- num_ctrl_qubits (int) – number of control qubits.
- label (str or None) – An optional label for the gate [Default: None]
- ctrl_state (int or str or None) – control state expressed as integer, string (e.g. ‘110’), or None. If None, use all 1s.
Returns
controlled version of this gate.
Return type
inverse
CXGate.inverse()
Return inverted CX gate (itself).
Attributes
ctrl_state
Return the control state of the gate as a decimal integer.
Return type
int
decompositions
Get the decompositions of the instruction from the SessionEquivalenceLibrary.
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.
Return type
List
duration
Get the duration.
label
Return instruction label
Return type
str
name
Get name of gate. If the gate has open controls the gate name will become:
<original_name_o<ctrl_state>
where <original_name> is the gate name for the default case of closed control qubits and <ctrl_state> is the integer value of the control state for the gate.
Return type
str
num_ctrl_qubits
Get number of control qubits.
Returns
The number of control qubits for the gate.
Return type
int
params
Get parameters from base_gate.
Returns
List of gate parameters.
Return type
list
Raises
CircuitError – Controlled gate does not define a base gate
unit
Get the time unit of duration.