qml.estimator.templates.PrepTHC

class PrepTHC(thc_ham, coeff_precision=None, select_swap_depth=None, wires=None)

Bases: ResourceOperator

Resource class for preparing the state for tensor hypercontracted (THC) Hamiltonian.

This operator customizes the Prepare circuit based on the structure of THC Hamiltonian.

Parameters:

• thc_ham (THCHamiltonian) – a tensor hypercontracted Hamiltonian for which the state is being prepared

• coeff_precision (int | None) – The number of bits used to represent the precision for loading the coefficients of Hamiltonian. If None is provided, the default value from the ResourceConfig is used.

• select_swap_depth (int | None) – A parameter of QROM used to trade-off extra wires for reduced circuit depth. Defaults to None, which internally determines the optimal depth.

• wires (WiresLike | None) – the wires on which the operator acts

Resources:

The resources are calculated based on Figures 3 and 4 in arXiv:2011.03494

Example

The resources for this operation are computed using:

>>> import pennylane.estimator as qre
>>> thc_ham = qre.THCHamiltonian(num_orbitals=20, tensor_rank=40)
>>> res = qre.estimate(qre.PrepTHC(thc_ham, coeff_precision=15))
>>> print(res)
--- Resources: ---
 Total wires: 185
    algorithmic wires: 12
    allocated wires: 173
         zero state: 28
         any state: 145
 Total gates : 1.485E+4
  'Toffoli': 467,
  'CNOT': 1.307E+4,
  'X': 512,
  'Hadamard': 797

Attributes

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

resource_keys = {'coeff_precision', 'select_swap_depth', 'thc_ham'}

resource_params

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

Returns:

A dictionary containing the resource parameters:

• thc_ham (THCHamiltonian): a tensor hypercontracted Hamiltonian for which the state is being prepared

• coeff_precision (int | None): The number of bits used to represent the precision for loading the coefficients of Hamiltonian. If None is provided, the default value from the ResourceConfig is used.

• select_swap_depth (int | None): A parameter of QROM used to trade-off extra wires for reduced circuit depth. Defaults to None, which internally determines the optimal depth.

Return type:

dict

Methods

adjoint_resource_decomp(target_resource_params)	Returns a list representing the resources of the adjoint of the operator.
resource_decomp(thc_ham[, coeff_precision, ...])	Returns a list representing the resources of the operator.
resource_rep(thc_ham[, coeff_precision, ...])	Returns a compressed representation containing only the parameters of the Operator that are needed to compute a resource estimation.

classmethod adjoint_resource_decomp(target_resource_params)

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

Parameters:

• thc_ham (THCHamiltonian) – a tensor hypercontracted Hamiltonian for which the walk operator is being created

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

Resources:

The resources are calculated based on Figures 3 and 4 in arXiv:2011.03494

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(thc_ham, coeff_precision=None, select_swap_depth=None)

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.

Parameters:

• thc_ham (THCHamiltonian) – a tensor hypercontracted Hamiltonian for which the walk operator is being created

• coeff_precision (int | None) – The number of bits used to represent the precision for loading the coefficients of Hamiltonian. If None is provided, the default value from the ResourceConfig is used.

• select_swap_depth (int | None) – A parameter of QROM used to trade-off extra qubits for reduced circuit depth. Defaults to None, which internally determines the optimal depth.

Resources:

The resources are calculated based on Figures 3 and 4 in arXiv:2011.03494

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(thc_ham, coeff_precision=None, select_swap_depth=None)

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

Parameters:

• thc_ham (THCHamiltonian) – a tensor hypercontracted Hamiltonian for which the state is being prepared

• coeff_precision (int | None) – The number of bits used to represent the precision for loading the coefficients of Hamiltonian. If None is provided, the default value from the ResourceConfig is used.

• select_swap_depth (int | None) – A parameter of QROM used to trade-off extra wires for reduced circuit depth. Defaults to None, which internally determines the optimal depth.

Returns:

the operator in a compressed representation

Return type:

CompressedResourceOp

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