Variational Gate — VQGate

API reference for parameterized (variational) gate variants used in variational quantum circuits (VQAs). These gates differ from standard gates in that their rotation parameters are symbolic references to a Parameter vector rather than fixed numeric values.

VQGate

Base class for variational quantum gates. VQGate objects are created by the variational gate factory functions and can be appended to VQCircuit.

Signature

python

class VQGate

VQGate instances hold a gate type and references to mutable parameter positions within a Parameter vector. At circuit execution time, concrete values are bound through VQCircuit.__call__().

Variational Gate Factory Functions

Each function returns a VQGate (i.e. VariationalQuantumGate). The param argument specifies the index in the Parameter vector that supplies the rotation angle.

Single-Qubit Variational Gates

P (variational)

python

P(qbit_idx: int, param: MutableParamType) -> VQGate

Parameter	Type	Description
qbit_idx	`int`	Target qubit index
param	`MutableParamType`	Index into the Parameter vector

Returns a variational P gate.

RX (variational)

python

RX(qbit_idx: int, param: MutableParamType) -> VQGate

Returns a variational $R_{X}$ gate.

RY (variational)

python

RY(qbit_idx: int, param: MutableParamType) -> VQGate

Returns a variational $R_{Y}$ gate.

RZ (variational)

python

RZ(qbit_idx: int, param: MutableParamType) -> VQGate

Returns a variational $R_{Z}$ gate.

U1 (variational)

python

U1(qbit_idx: int, param: MutableParamType) -> VQGate

Returns a variational U1 gate.

IDLE (variational)

python

IDLE(qbit_idx: int, param: MutableParamType) -> VQGate

Returns a variational IDLE gate.

Two-Parameter Variational Gates

U2 (variational, overload 1)

python

U2(qbit_idx: int, param1: MutableParamType, param2: Union[float, MutableParamType]) -> VQGate

Parameter	Type	Description
qbit_idx	`int`	Target qubit index
param1	`MutableParamType`	Mutable parameter index for first angle
param2	`Union[float, MutableParamType]`	Fixed value or mutable parameter index for second angle

U2 (variational, overload 2)

python

U2(qbit_idx: int, param1: float, param2: MutableParamType) -> VQGate

Parameter	Type	Description
qbit_idx	`int`	Target qubit index
param1	`float`	Fixed value for first angle
param2	`MutableParamType`	Mutable parameter index for second angle

RPhi (variational, overload 1)

python

RPhi(qbit_idx: int, param1: MutableParamType, param2: Union[float, MutableParamType]) -> VQGate

Parameter	Type	Description
qbit_idx	`int`	Target qubit index
param1	`MutableParamType`	Mutable parameter index for theta
param2	`Union[float, MutableParamType]`	Fixed value or mutable parameter index for phi

RPhi (variational, overload 2)

python

RPhi(qbit_idx: int, param1: float, param2: MutableParamType) -> VQGate

Parameter	Type	Description
qbit_idx	`int`	Target qubit index
param1	`float`	Fixed value for theta
param2	`MutableParamType`	Mutable parameter index for phi

Three-Parameter Variational Gates

U3 (variational, overload 1)

python

U3(qbit_idx: int, param1: MutableParamType, param2: Union[float, MutableParamType], param3: Union[float, MutableParamType]) -> VQGate

Parameter	Type	Description
qbit_idx	`int`	Target qubit index
param1	`MutableParamType`	Mutable parameter index for first angle
param2	`Union[float, MutableParamType]`	Fixed value or mutable parameter index for second angle
param3	`Union[float, MutableParamType]`	Fixed value or mutable parameter index in third angle

U3 (variational, overload 2)

python

U3(qbit_idx: int, param1: float, param2: MutableParamType, param3: Union[float, MutableParamType]) -> VQGate

Parameter	Type	Description
qbit_idx	`int`	Target qubit index
param1	`float`	Fixed value for first angle
param2	`MutableParamType`	Mutable parameter index in second angle
param3	`Union[float, MutableParamType]`	Fixed value or mutable parameter index in third angle

U3 (variational, overload 3)

python

U3(qbit_idx: int, param1: float, param2: float, param3: MutableParamType) -> VQGate

Parameter	Type	Description
qbit_idx	`int`	Target qubit index
param1	`float`	Fixed value for first angle
param2	`float`	Fixed value in second angle
param3	`MutableParamType`	Mutable parameter index in third angle

Four-Parameter Variational Gates

U4 (variational, overload 1)

python

U4(qbit_idx: int, param1: MutableParamType, param2: Union[float, MutableParamType], param3: Union[float, MutableParamType], param4: Union[float, MutableParamType]) -> VQGate

Parameter	Type	Description
qbit_idx	`int`	Target qubit index
param1	`MutableParamType`	Mutable parameter index for first angle
param2	`Union[float, MutableParamType]`	Fixed value or mutable parameter index in second angle
param3	`Union[float, MutableParamType]`	Fixed value or mutable parameter index in third angle
param4	`Union[float, MutableParamType]`	Fixed value or mutable parameter index in fourth angle

U4 (variational, overload 2)

python

U4(qbit_idx: int, param1: float, param2: MutableParamType, param3: Union[float, MutableParamType], param4: Union[float, MutableParamType]) -> VQGate

Parameter	Type	Description
qbit_idx	`int`	Target qubit index
param1	`float`	Fixed value in first angle
param2	`MutableParamType`	Mutable parameter index in second angle
param3	`Union[float, MutableParamType]`	Fixed value or mutable parameter index in third angle
param4	`Union[float, MutableParamType]`	Fixed value or mutable parameter index in fourth angle

U4 (variational, overload 3)

python

U4(qbit_idx: int, param1: float, param2: float, param3: MutableParamType, param4: Union[float, MutableParamType]) -> VQGate

Parameter	Type	Description
qbit_idx	`int`	Target qubit index
param1	`float`	Fixed value in first angle
param2	`float`	Fixed value in second angle
param3	`MutableParamType`	Mutable parameter index in third angle
param4	`Union[float, MutableParamType]`	Fixed value or mutable parameter index in fourth angle

U4 (variational, overload 4)

python

U4(qbit_idx: int, param1: float, param2: float, param3: float, param4: MutableParamType) -> VQGate

Parameter	Type	Description
qbit_idx	`int`	Target qubit index
param1	`float`	Fixed value in first angle
param2	`float`	Fixed value in second angle
param3	`float`	Fixed value in third angle
param4	`MutableParamType`	Mutable parameter index in fourth angle

Two-Qubit Variational Gates

CU (variational, overload 1)

python

CU(control_qbit_idx: int, target_qbit_idx: int, param1: MutableParamType, param2: Union[float, MutableParamType], param3: Union[float, MutableParamType], param4: Union[float, MutableParamType]) -> VQGate

Parameter	Type	Description
control_qbit_idx	`int`	Control qubit index
target_qbit_idx	`int`	Target qubit index
param1	`MutableParamType`	Mutable parameter index in first angle
param2	`Union[float, MutableParamType]`	Fixed value or mutable parameter index in second angle
param3	`Union[float, MutableParamType]`	Fixed value or mutable parameter index in third angle
param4	`Union[float, MutableParamType]`	Fixed value or mutable parameter index in fourth angle

CU (variational, overloads 2-4)

Additional overloads follow the same pattern as U4, with one additional fixed value per overload. Each overload takes control_qbit_idx and target_qbit_idx as the first two arguments.

CP (variational)

python

CP(control_qbit_idx: int, target_qbit_idx: int, param: MutableParamType) -> VQGate

Parameter	Type	Description
control_qbit_idx	`int`	Control qubit index
target_qbit_idx	`int`	Target qubit index
param	`MutableParamType`	Mutable parameter index

CRX (variational)

python

CRX(control_qbit_idx: int, target_qbit_idx: int, param: MutableParamType) -> VQGate

Parameter	Type	Description
control_qbit_idx	`int`	Control qubit index
target_qbit_idx	`int`	Target qubit index
param	`MutableParamType`	Mutable parameter index

CRY (variational)

python

CRY(control_qbit_idx: int, target_qbit_idx: int, param: MutableParamType) -> VQGate

CRZ (variational)

python

CRZ(control_qbit_idx: int, target_qbit_idx: int, param: MutableParamType) -> VQGate

CR (variational, alias for CP)

python

CR(control_qbit_idx: int, target_qbit_idx: int, param: MutableParamType) -> VQGate

RXX (variational)

python

RXX(control_qbit_idx: int, target_qbit_idx: int, param: MutableParamType) -> VQGate

RYY (variational)

python

RYY(control_qbit_idx: int, target_qbit_idx: int, param: MutableParamType) -> VQGate

RZZ (variational)

python

RZZ(control_qbit_idx: int, target_qbit_idx: int, param: MutableParamType) -> VQGate

RZX (variational)

python

RZX(control_qbit_idx: int, target_qbit_idx: int, param: MutableParamType) -> VQGate

Usage with VQCircuit

Variational gates are the building blocks of VQCircuit. The param argument refers to a position in the Parameter vector:

python

from pyqpanda3.vqcircuit import VQCircuit
from pyqpanda3.core import RX, CP

# Create a variational circuit
vqc = VQCircuit()

# Create parameter placeholders (returns index positions)
p0 = vqc.Param("rx0")   # parameter for first RX
p1 = vqc.Param("rx1")   # parameter for second RX
p2 = vqc.Param("cp")    # parameter for controlled-phase

# Add variational gates using parameter indices
vqc << RX(0, p0)         # RX on qubit 0, angle from p0
vqc << RX(1, p1)         # RX on qubit 1, angle from p1
vqc << CP(0, 1, p2)      # Controlled-Phase using p2
vqc << RX(0, p2)         # RX on qubit 0, angle from p2

# Get parameter values and bind concrete values
import numpy as np
theta = np.array([0.5, 0.3, 0.1])
result = vqc(theta)  # pass concrete values

Variational Gate — VQGate ​

VQGate ​

Signature ​

Variational Gate Factory Functions ​

Single-Qubit Variational Gates ​

P (variational) ​

RX (variational) ​

RY (variational) ​

RZ (variational) ​

U1 (variational) ​

IDLE (variational) ​

Two-Parameter Variational Gates ​

U2 (variational, overload 1) ​

U2 (variational, overload 2) ​

RPhi (variational, overload 1) ​

RPhi (variational, overload 2) ​

Three-Parameter Variational Gates ​

U3 (variational, overload 1) ​

U3 (variational, overload 2) ​

U3 (variational, overload 3) ​

Four-Parameter Variational Gates ​

U4 (variational, overload 1) ​

U4 (variational, overload 2) ​

U4 (variational, overload 3) ​

U4 (variational, overload 4) ​

Two-Qubit Variational Gates ​

CU (variational, overload 1) ​

CU (variational, overloads 2-4) ​

CP (variational) ​

CRX (variational) ​

CRY (variational) ​

CRZ (variational) ​

CR (variational, alias for CP) ​

RXX (variational) ​

RYY (variational) ​

RZZ (variational) ​

RZX (variational) ​

Usage with VQCircuit ​

See Also ​

Variational Gate — VQGate

VQGate

Signature

Variational Gate Factory Functions

Single-Qubit Variational Gates

P (variational)

RX (variational)

RY (variational)

RZ (variational)

U1 (variational)

IDLE (variational)

Two-Parameter Variational Gates

U2 (variational, overload 1)

U2 (variational, overload 2)

RPhi (variational, overload 1)

RPhi (variational, overload 2)

Three-Parameter Variational Gates

U3 (variational, overload 1)

U3 (variational, overload 2)

U3 (variational, overload 3)

Four-Parameter Variational Gates

U4 (variational, overload 1)

U4 (variational, overload 2)

U4 (variational, overload 3)

U4 (variational, overload 4)

Two-Qubit Variational Gates

CU (variational, overload 1)

CU (variational, overloads 2-4)

CP (variational)

CRX (variational)

CRY (variational)

CRZ (variational)

CR (variational, alias for CP)

RXX (variational)

RYY (variational)

RZZ (variational)

RZX (variational)

Usage with VQCircuit

See Also