qiskit.aqua.components.eigs.EigsQPE

class EigsQPE(operator, iqft, num_time_slices=1, num_ancillae=1, expansion_mode='trotter', expansion_order=1, evo_time=None, negative_evals=False, ne_qfts=None)

Eigenvalues using Quantum Phase Estimation.

Specifically, this class is based on PhaseEstimationCircuit with no measurements and has additional handling of negative eigenvalues, e.g. for HHL. It depends on the QFT class.

Parameters

• operator (LegacyBaseOperator) – The Hamiltonian Operator object

• iqft (QuantumCircuit) – The Inverse Quantum Fourier Transform circuit

• num_time_slices (int) – The number of time slices, has a minimum value of 1.

• num_ancillae (int) – The number of ancillary qubits to use for the measurement, has a minimum value of 1.

• expansion_mode (str) – The expansion mode (‘trotter’ | ‘suzuki’)

• expansion_order (int) – The suzuki expansion order, has a minimum value of 1.

• evo_time (Optional[float]) – An optional evolution time which should scale the eigenvalue onto the range \((0,1]\) (or \((-0.5,0.5]\) for negative eigenvalues). Defaults to None in which case a suitably estimated evolution time is internally computed.

• negative_evals (bool) – Set True to indicate negative eigenvalues need to be handled

• ne_qfts (Optional[List]) – The QFT and IQFT circuits for handling negative eigenvalues

__init__(operator, iqft, num_time_slices=1, num_ancillae=1, expansion_mode='trotter', expansion_order=1, evo_time=None, negative_evals=False, ne_qfts=None)

Parameters

• operator (LegacyBaseOperator) – The Hamiltonian Operator object

• iqft (QuantumCircuit) – The Inverse Quantum Fourier Transform circuit

• num_time_slices (int) – The number of time slices, has a minimum value of 1.

• num_ancillae (int) – The number of ancillary qubits to use for the measurement, has a minimum value of 1.

• expansion_mode (str) – The expansion mode (‘trotter’ | ‘suzuki’)

• expansion_order (int) – The suzuki expansion order, has a minimum value of 1.

• evo_time (Optional[float]) – An optional evolution time which should scale the eigenvalue onto the range \((0,1]\) (or \((-0.5,0.5]\) for negative eigenvalues). Defaults to None in which case a suitably estimated evolution time is internally computed.

• negative_evals (bool) – Set True to indicate negative eigenvalues need to be handled

• ne_qfts (Optional[List]) – The QFT and IQFT circuits for handling negative eigenvalues

Methods

__init__(operator, iqft[, num_time_slices, …])	type operator LegacyBaseOperator
construct_circuit(mode[, register])	Construct the eigenvalues estimation using the PhaseEstimationCircuit
construct_inverse(mode, circuit)	Construct the inverse eigenvalue estimation quantum circuit.
get_register_sizes()	get register sizes
get_scaling()	get scaling

construct_circuit(mode, register=None)

Construct the eigenvalues estimation using the PhaseEstimationCircuit

Parameters

• mode (str) – construction mode, ‘matrix’ not supported

• register (QuantumRegister) – the register to use for the quantum state

Returns

object for the constructed circuit

Return type

QuantumCircuit

Raises

ValueError – QPE is only possible as a circuit not as a matrix

construct_inverse(mode, circuit)

Construct the inverse eigenvalue estimation quantum circuit.

Parameters

• mode (str) – construction mode, ‘matrix’ not supported

• circuit (QuantumCircuit) – the quantum circuit to invert

Returns

object for of the inverted eigenvalue estimation

circuit.

Return type

QuantumCircuit

Raises

• NotImplementedError – not implemented for matrix mode

• ValueError – Circuit was not constructed beforehand

get_register_sizes()

get register sizes

get_scaling()

get scaling