CPhaseGate
class qiskit.circuit.library.CPhaseGate(theta, label=None, ctrl_state=None, *, duration=None, unit='dt', _base_label=None)
Bases: ControlledGate
Controlled-Phase gate.
This is a diagonal and symmetric gate that induces a phase on the state of the target qubit, depending on the control state.
Can be applied to a QuantumCircuit
with the cp()
method.
Circuit symbol:
q_0: ─■──
│λ
q_1: ─■──
Matrix representation:
CRZGate
: Due to the global phase difference in the matrix definitions of Phase and RZ, CPhase and CRZ are different gates with a relative phase difference.
Create new CPhase gate.
Attributes
base_class
Get the base class of this instruction. This is guaranteed to be in the inheritance tree of self
.
The “base class” of an instruction is the lowest class in its inheritance tree that the object should be considered entirely compatible with for _all_ circuit applications. This typically means that the subclass is defined purely to offer some sort of programmer convenience over the base class, and the base class is the “true” class for a behavioral perspective. In particular, you should not override base_class
if you are defining a custom version of an instruction that will be implemented differently by hardware, such as an alternative measurement strategy, or a version of a parametrized gate with a particular set of parameters for the purposes of distinguishing it in a Target
from the full parametrized gate.
This is often exactly equivalent to type(obj)
, except in the case of singleton instances of standard-library instructions. These singleton instances are special subclasses of their base class, and this property will return that base. For example:
>>> isinstance(XGate(), XGate)
True
>>> type(XGate()) is XGate
False
>>> XGate().base_class is XGate
True
In general, you should not rely on the precise class of an instruction; within a given circuit, it is expected that Instruction.name
should be a more suitable discriminator in most situations.
condition
The classical condition on the instruction.
condition_bits
Get Clbits in condition.
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. If the gate has open controls, as determined from ctrl_state
, the returned definition is conjugated with X without changing the internal _definition
.
duration
Get the duration.
label
Return instruction label
mutable
Is this instance is a mutable unique instance or not.
If this attribute is False
the gate instance is a shared singleton and is not mutable.
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.
num_clbits
Return the number of clbits.
num_ctrl_qubits
num_qubits
Return the number of qubits.
params
Get parameters from base_gate.
Returns
List of gate parameters.
Return type
Raises
CircuitError – Controlled gate does not define a base gate
unit
Get the time unit of duration.
Methods
control
control(num_ctrl_qubits=1, label=None, ctrl_state=None, annotated=None)
Controlled version of this gate.
Parameters
- num_ctrl_qubits (int) – number of control qubits.
- label (str | None) – An optional label for the gate [Default:
None
] - ctrl_state (str |int | None) – control state expressed as integer, string (e.g.``’110’
), or ``None
. IfNone
, use all 1s. - annotated (bool | None) – indicates whether the controlled gate should be implemented as an annotated gate. If
None
, this is handled asFalse
.
Returns
controlled version of this gate.
Return type
inverse
power
power(exponent, annotated=False)
Raise this gate to the power of exponent
.
Implemented either as a unitary gate (ref. UnitaryGate
) or as an annotated operation (ref. AnnotatedOperation
). In the case of several standard gates, such as RXGate
, when the power of a gate can be expressed in terms of another standard gate that is returned directly.
Parameters
- exponent (float) – the power to raise the gate to
- annotated (bool) – indicates whether the power gate can be implemented as an annotated operation. In the case of several standard gates, such as
RXGate
, this argument is ignored when the power of a gate can be expressed in terms of another standard gate.
Returns
An operation implementing gate^exponent
Raises
CircuitError – If gate is not unitary