qml.labs.resource_estimation.ResourceControlledPhaseShift

class ResourceControlledPhaseShift(eps=None, wires=None)

Bases: ResourceOperator

Resource class for the ControlledPhaseShift gate.

Parameters:

• wires (Sequence[int], optional) – the wire the operation acts on

• eps (float, optional) – 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 ResourcePhaseShift gate is identical to the ResourceRZ gate up to some global phase. Furthermore, a controlled global phase simplifies to a ResourcePhaseShift 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 ResourceCNOT gates and three ResourceRZ gates.

See also

ControlledPhaseShift

Example

The resources for this operation are computed using:

>>> re.ResourceControlledPhaseShift.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 = {'eps'}

resource_params

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

Returns:

• eps (Union[float, None]): error threshold for the approximation

Return type:

A dictionary containing the resource parameters

Methods

adjoint_resource_decomp(*args, **kwargs)	Returns a list of actions that define the resources of the operator.
controlled_resource_decomp(...)	Returns a list representing the resources for a controlled version of the operator.
default_adjoint_resource_decomp([eps])	Returns a list representing the resources for the adjoint of the operator.
default_controlled_resource_decomp(...[, eps])	Returns a list representing the resources for a controlled version of the operator.
default_pow_resource_decomp(pow_z[, eps])	Returns a list representing the resources for an operator raised to a power.
default_resource_decomp([eps])	Returns a list of GateCount objects representing the resources of the operator.
dequeue(op_to_remove[, context])	Remove the given resource operator(s) from the Operator queue.
pow_resource_decomp(pow_z, *args, **kwargs)	Returns a list representing the resources for an operator raised to a power.
queue([context])	Append the operator to the Operator queue.
resource_decomp(*args, **kwargs)	Returns a list of actions that define the resources of the operator.
resource_rep([eps])	Returns a compressed representation containing only the parameters of the Operator that are needed to compute the resources.
resource_rep_from_op()	Returns a compressed representation directly from the operator
set_resources(new_func[, override_type])	Set a custom function to override the default resource decomposition.
tracking_name(*args, **kwargs)	Returns a name used to track the operator during resource estimation.
tracking_name_from_op()	Returns the tracking name built with the operator's parameters.

classmethod adjoint_resource_decomp(*args, **kwargs)

Returns a list of actions that define the resources of the operator.

classmethod controlled_resource_decomp(ctrl_num_ctrl_wires, ctrl_num_ctrl_values, *args, **kwargs)

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

Parameters:

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

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

classmethod default_adjoint_resource_decomp(eps=None)

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

Resources:

The adjoint of a phase shift just flips the sign of the phase angle, thus the resources of the adjoint operation result in the original 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 default_controlled_resource_decomp(ctrl_num_ctrl_wires, ctrl_num_ctrl_values, eps=None)

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

Parameters:

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

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

• eps (float, optional) – 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 expressed using the symbolic ResourceControlled. The resources are computed according to the controlled_resource_decomp() of the base ResourcePhaseShift 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 default_pow_resource_decomp(pow_z, eps=None)

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

• eps (float, optional) – 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:

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 default_resource_decomp(eps=None, **kwargs)

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

Parameters:

eps (float, optional) – 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 ResourcePhaseShift gate is identical to the ResourceRZ gate up to some global phase. Furthermore, a controlled global phase simplifies to a ResourcePhaseShift 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 ResourceCNOT gates and three ResourceRZ gates.

See also

ControlledPhaseShift

Example

The resources for this operation are computed using:

>>> re.ResourceControlledPhaseShift.resource_decomp()
[(2 x CNOT), (3 x RZ)]

static dequeue(op_to_remove, context=<class 'pennylane.queuing.QueuingManager'>)

Remove the given resource operator(s) from the Operator queue.

classmethod pow_resource_decomp(pow_z, *args, **kwargs)

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

Parameters:

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

queue(context=<class 'pennylane.queuing.QueuingManager'>)

Append the operator to the Operator queue.

classmethod resource_decomp(*args, **kwargs)

Returns a list of actions that define the resources of the operator.

classmethod resource_rep(eps=None)

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

resource_rep_from_op()

Returns a compressed representation directly from the operator

classmethod set_resources(new_func, override_type='base')

Set a custom function to override the default resource decomposition.

This method allows users to replace any of the resource_decomp, adjoint_resource_decomp, ctrl_resource_decomp, or pow_resource_decomp methods globally for every instance of the class.

classmethod tracking_name(*args, **kwargs)

Returns a name used to track the operator during resource estimation.

tracking_name_from_op()

Returns the tracking name built with the operator’s parameters.

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