qml.estimator.ops.ControlledPhaseShift

class ControlledPhaseShift(precision=None, wires=None)

Bases: ResourceOperator

Resource class for the ControlledPhaseShift gate.

Parameters:

• wires (Sequence[int] | None) – the wire the operation acts on

• precision (float | None) – The error threshold for Clifford + T decomposition of the rotation gate. The default value is None which corresponds to using the epsilon stated in the config.

Resources:

The resources are derived using the fact that a PhaseShift gate is identical to the RZ gate up to some global phase. Furthermore, a controlled global phase simplifies to a PhaseShift gate. This gives rise to the following identity:

\[CR_\phi(\phi) = (R_\phi(\phi/2) \otimes I) \cdot CNOT \cdot (I \otimes R_\phi(-\phi/2)) \cdot CNOT \cdot (I \otimes R_\phi(\phi/2))\]

Specifically, the resources are defined as two CNOT gates and three RZ gates.

See also

The corresponding PennyLane operation ControlledPhaseShift.

Example

The resources for this operation are computed using:

>>> qml.estimator.ControlledPhaseShift.resource_decomp()
[(2 x CNOT), (3 x RZ)]

Attributes

num_wires
resource_keys
resource_params	Returns a dictionary containing the minimal information needed to compute the resources.

num_wires = 2

resource_keys = {'precision'}

resource_params

Returns a dictionary containing the minimal information needed to compute the resources.

Returns:

A dictionary containing the resource parameters:

• precision (float | None): the number of qubits the operation is controlled on

Return type:

dict

Methods

adjoint_resource_decomp(target_resource_params)	Returns a list representing the resources for the adjoint of the operator.
controlled_resource_decomp(num_ctrl_wires, ...)	Returns a list representing the resources for a controlled version of the operator.
pow_resource_decomp(pow_z, ...)	Returns a list representing the resources for an operator raised to a power.
resource_decomp([precision])	Returns a list of GateCount objects representing the resources of the operator.
resource_rep([precision])	Returns a compressed representation containing only the parameters of the operator that are needed to compute the resources.

classmethod adjoint_resource_decomp(target_resource_params)

Returns a list representing the resources for the adjoint of the operator.

Parameters:

target_resource_params (dict) – A dictionary containing the resource parameters of the target operator.

Resources:

The adjoint of a phase shift just flips the sign of the phase angle, thus the resources of the adjoint operation result are same as the originial operation.

Returns:

A list of GateCount objects, where each object represents a specific quantum gate and the number of times it appears in the decomposition.

Return type:

list[GateCount]

classmethod controlled_resource_decomp(num_ctrl_wires, num_zero_ctrl, target_resource_params)

Returns a list representing the resources for a controlled version of the operator.

Parameters:

• num_ctrl_wires (int) – the number of qubits the operation is controlled on

• num_zero_ctrl (int) – the number of control qubits, that are controlled when in the \(|0\rangle\) state

• target_resource_params (dict) – A dictionary containing the resource parameters of the target operator.

Resources:

The resources are expressed using the symbolic Controlled. The resources are computed according to the controlled_resource_decomp() of the base PhaseShift class.

Returns:

A list of GateCount objects, where each object represents a specific quantum gate and the number of times it appears in the decomposition.

Return type:

list[GateCount]

classmethod pow_resource_decomp(pow_z, target_resource_params)

Returns a list representing the resources for an operator raised to a power.

Parameters:

• pow_z (int) – the power that the operator is being raised to

• target_resource_params (dict) – A dictionary containing the resource parameters of the target operator.

Resources:

Taking arbitrary powers of a phase shift produces a sum of shifts. The resources simplify to just one total phase shift operator.

Returns:

A list of GateCount objects, where each object represents a specific quantum gate and the number of times it appears in the decomposition.

Return type:

list[GateCount]

classmethod resource_decomp(precision=None)

Returns a list of GateCount objects representing the resources of the operator.

Parameters:

precision (float | None) – The error threshold for clifford plus T decomposition of the rotation gate. The default value is None which corresponds to using the epsilon stated in the config.

Resources:

The resources are derived using the fact that a PhaseShift gate is identical to the RZ gate up to some global phase. Furthermore, a controlled global phase simplifies to a PhaseShift gate. This gives rise to the following identity:

\[CR_\phi(\phi) = (R_\phi(\phi/2) \otimes I) \cdot CNOT \cdot (I \otimes R_\phi(-\phi/2)) \cdot CNOT \cdot (I \otimes R_\phi(\phi/2))\]

Specifically, the resources are defined as two CNOT gates and three RZ gates.

See also

The corresponding PennyLane operation ControlledPhaseShift.

Returns:

A list of GateCount objects, where each object represents a specific quantum gate and the number of times it appears in the decomposition.

Return type:

list[GateCount]

Example

The resources for this operation are computed using:

>>> qml.estimator.ControlledPhaseShift.resource_decomp()
[(2 x CNOT), (3 x RZ)]

classmethod resource_rep(precision=None)

Returns a compressed representation containing only the parameters of the operator that are needed to compute the resources.

Parameters:

precision (float | None) – The error threshold for the Clifford + T decomposition of this operation.

Returns:

A compressed representation of the operator.

Return type:

CompressedResourceOp

code/api/pennylane.estimator.ops.ControlledPhaseShift

 

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