qml.labs.resource_estimation.ResourcePhaseShift

class ResourcePhaseShift(epsilon=None, wires=None)

Bases: ResourceOperator

Resource class for the PhaseShift gate.

Keyword Arguments:

• eps (float, optional) – The error threshold for clifford plus T decomposition of this operation. The default value is None which corresponds to using the epsilon stated in the config.

• wires (Any or Wires, optional) – the wire the operation acts on

Resources:

The phase shift gate is equivalent to a Z-rotation upto some global phase, as defined from the following identity:

\[\begin{split}R_\phi(\phi) = e^{i\phi/2}R_z(\phi) = \begin{bmatrix} 1 & 0 \\ 0 & e^{i\phi} \end{bmatrix}.\end{split}\]

See also

PhaseShift

Example

The resources for this operation are computed as:

>>> plre.ResourcePhaseShift.resource_decomp()
[(1 x RZ), (1 x GlobalPhase)]

Attributes

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

num_wires = 1

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 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 operator just changes the sign of the phase, thus the resources of the adjoint operation results 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) – error threshold for clifford plus T decomposition of this operation

Resources:

For a single control wire, the cost is a single instance of ResourceControlledPhaseShift. Two additional ResourceX gates are used to flip the control qubit if it is zero-controlled.

In the case where multiple controlled wires are provided, we can collapse the control wires by introducing one ‘clean’ auxilliary qubit (which gets reset at the end). In this case the cost increases by two additional ResourceMultiControlledX gates, as described in (lemma 7.11) Elementary gates for quantum computation.

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

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 representing the resources of the operator. Each object represents a quantum gate and the number of times it occurs in the decomposition.

Keyword Arguments:

eps (float) – error threshold for clifford plus T decomposition of this operation

Resources:

The phase shift gate is equivalent to a Z-rotation upto some global phase, as defined from the following identity:

\[\begin{split}R_\phi(\phi) = e^{i\phi/2}R_z(\phi) = \begin{bmatrix} 1 & 0 \\ 0 & e^{i\phi} \end{bmatrix}.\end{split}\]

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]

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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