qml.labs.resource_estimation.ResourceTwoQubitComparator

class ResourceTwoQubitComparator(wires=None)

Bases: ResourceOperator

Resource class for comparing the integer values encoded in two quantum registers of two qubits each.

This operation modifies the input registers. The original values can be restored by applying the operation’s adjoint.

Parameters:

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

Resources:

The resources are obtained from appendix B, Figure 3 in arXiv:1711.10460. Specifically, the resources are given as \(2\) CSWAP gates, \(3\) CNOT gates, and \(1\) X gate. This decomposition requires one clean auxiliary qubit. The circuit which applies the comparison operation on registers \((x0,x1)\) and \((y0, y1)\) is defined as:

 x1 : ─╭X─╭●────╭●───────┤
 y1 : ─╰●─│─────├SWAP────┤
 x0 : ─╭X─├SWAP─│─────╭X─┤
 y0 : ─╰●─│─────╰SWAP─╰●─┤
|1> : ────╰SWAP──────────┤

Example

The resources for this operation are computed using:

>>> two_qubit_compare = plre.ResourceTwoQubitComparator()
>>> print(plre.estimate(two_qubit_compare))
--- Resources: ---
 Total qubits: 5
 Total gates : 10
 Qubit breakdown:
  clean qubits: 1, dirty qubits: 0, algorithmic qubits: 4
 Gate breakdown:
  {'Toffoli': 2, 'CNOT': 7, 'X': 1}

Attributes

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

num_wires = 4

resource_keys = {}

resource_params

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

Returns:

An empty dictionary

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(**kwargs)	Returns a list representing the resources of the operator.
resource_rep()	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
tempand_based_decomp(**kwargs)	Returns a list representing the resources of the operator.
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 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(**kwargs)

Returns a list representing the resources of the operator. Each object in the list represents a gate and the number of times it occurs in the circuit.

Resources:

The resources are obtained from appendix B, Figure 3 in arXiv:1711.10460. Specifically, the resources are given as \(2\) CSWAP gates, \(3\) CNOT gates, and \(1\) X gate. This decomposition requires one clean auxiliary qubit. The circuit which applies the comparison operation on registers \((x0,x1)\) and \((y0, y1)\) is defined as:

 x1 : ─╭X─╭●────╭●───────┤
 y1 : ─╰●─│─────├SWAP────┤
 x0 : ─╭X─├SWAP─│─────╭X─┤
 y0 : ─╰●─│─────╰SWAP─╰●─┤
|1> : ────╰SWAP──────────┤

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_rep()

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

Returns:

the operator in a compressed representation

Return type:

CompressedResourceOp

resource_rep_from_op()

Returns a compressed representation directly from the operator

classmethod tempand_based_decomp(**kwargs)

Returns a list representing the resources of the operator. Each object in the list represents a gate and the number of times it occurs in the circuit.

Resources:

The resources are obtained from appendix B, Figure 3 in arXiv:1711.10460. Specifically, the resources are given as \(2\) CSWAP gates, \(3\) CNOT gates, and \(1\) X gate. This decomposition is modified to use TempAND gates for building blocks of CSWAP gates.

 x1 : ─╭X─╭●────╭●───────┤
 y1 : ─╰●─│─────├SWAP────┤
 x0 : ─╭X─├SWAP─│─────╭X─┤
 y0 : ─╰●─│─────╰SWAP─╰●─┤
|1> : ────╰SWAP──────────┤

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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