qml.labs.resource_estimation.ResourceQPE

class ResourceQPE(base, num_estimation_wires, adj_qft_op=None, wires=None)

Bases: ResourceOperator

Resource class for QuantumPhaseEstimation (QPE).

Parameters:

• base (ResourceOperator) – the phase estimation operator

• num_estimation_wires (int) – the number of wires used for measuring out the phase

• adj_qft_op (Union[ResourceOperator, None]) – An optional argument to set the subroutine used to perform the adjoint QFT operation.

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

Resources:

The resources are obtained from the standard decomposition of QPE as presented in (Section 5.2) Nielsen, M.A. and Chuang, I.L. (2011) Quantum Computation and Quantum Information.

See also

QuantumPhaseEstimation

Example

The resources for this operation are computed using:

>>> gate_set = {"Hadamard", "Adjoint(QFT(5))", "CRX"}
>>> qpe = plre.ResourceQPE(plre.ResourceRX(precision=1e-3), 5)
>>> print(plre.estimate(qpe, gate_set))
--- Resources: ---
 Total qubits: 6
 Total gates : 11
 Qubit breakdown:
  clean qubits: 0, dirty qubits: 0, algorithmic qubits: 6
 Gate breakdown:
  {'Hadamard': 5, 'CRX': 5, 'Adjoint(QFT(5))': 1}

Usage Details

Additionally, we can customize the implementation of the QFT operator we wish to use within the textbook QPE algorithm. This allows users to optimize the implementation of QPE by using more efficient implementations of the QFT.

For example, consider the cost using the default QFT implmentation below:

>>> qpe = plre.ResourceQPE(plre.ResourceRX(precision=1e-3), 5, adj_qft_op=None)
>>> print(plre.estimate(qpe))
--- Resources: ---
 Total qubits: 6
 Total gates : 1.586E+3
 Qubit breakdown:
  clean qubits: 0, dirty qubits: 0, algorithmic qubits: 6
 Gate breakdown:
  {'Hadamard': 20, 'CNOT': 36, 'T': 1.530E+3}

Now we use the ResourceAQFT class:

>>> aqft = plre.ResourceAQFT(order=3, num_wires=5)
>>> adj_aqft = plre.ResourceAdjoint(aqft)
>>> qpe = plre.ResourceQPE(plre.ResourceRX(precision=1e-3), 5, adj_qft_op=adj_aqft)
>>> print(plre.estimate(qpe))
--- Resources: ---
 Total qubits: 8
 Total gates : 321
 Qubit breakdown:
  clean qubits: 2, dirty qubits: 0, algorithmic qubits: 6
 Gate breakdown:
  {'Hadamard': 38, 'CNOT': 34, 'T': 222, 'Toffoli': 7, 'X': 4, 'S': 8, 'Z': 8}

Attributes

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

num_wires = 1

resource_keys = {'adj_qft_cmpr_op', 'base_cmpr_op', 'num_estimation_wires'}

resource_params

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

Returns:

A dictionary containing the resource parameters:

• base_cmpr_op (CompressedResourceOp): A compressed resource operator, corresponding to the phase estimation operator.

• num_estimation_wires (int): the number of wires used for measuring out the phase

• adj_qft_cmpr_op (Union[CompressedResourceOp, None]): An optional compressed resource operator, corresponding to the adjoint QFT routine. If None, the default ResourceQFT will be used.

Return type:

dict

Methods

adjoint_resource_decomp(*args, **kwargs)	Returns a list representing the resources for the adjoint of the operator.
controlled_resource_decomp(...)	Returns a list representing the resources for a controlled version 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(base_cmpr_op, ...)	Returns a dictionary representing the resources of the operator.
resource_rep(base_cmpr_op, ...)	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
tracking_name(base_cmpr_op, ...)	Returns the tracking name built with the operator's parameters.
tracking_name_from_op()	Returns the tracking name built with the operator's parameters.

classmethod adjoint_resource_decomp(*args, **kwargs)

Returns a list representing the resources for the adjoint 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

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(base_cmpr_op, num_estimation_wires, adj_qft_cmpr_op, **kwargs)

Returns a dictionary representing the resources of the operator. The keys are the operators and the associated values are the counts.

Parameters:

• base_cmpr_op (CompressedResourceOp) – A compressed resource operator, corresponding to the phase estimation operator.

• num_estimation_wires (int) – the number of wires used for measuring out the phase

• adj_qft_cmpr_op (Union[CompressedResourceOp, None]) – An optional compressed resource operator, corresponding to the adjoint QFT routine. If None, the default ResourceQFT will be used.

Resources:

The resources are obtained from the standard decomposition of QPE as presented in (section 5.2) Nielsen, M.A. and Chuang, I.L. (2011) Quantum Computation and Quantum Information.

classmethod resource_rep(base_cmpr_op, num_estimation_wires, adj_qft_cmpr_op)

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

Parameters:

• base_cmpr_op (CompressedResourceOp) – A compressed resource operator, corresponding to the phase estimation operator.

• num_estimation_wires (int) – the number of wires used for measuring out the phase

• adj_qft_cmpr_op (Union[CompressedResourceOp, None]) – An optional compressed resource operator, corresponding to the adjoint QFT routine. If None, the default ResourceQFT will be used.

Returns:

the operator in a compressed representation

Return type:

CompressedResourceOp

resource_rep_from_op()

Returns a compressed representation directly from the operator

static tracking_name(base_cmpr_op, num_estimation_wires, adj_qft_cmpr_op)

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

tracking_name_from_op()

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

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