qdk_chemistry.plugins.qiskit.standard_phase_estimation module

Standard (QFT-based) phase estimation implementation via qiskit.

This module implements the standard quantum phase estimation algorithm using the qiskit synthesis of the inverse Quantum Fourier Transform (QFT), which measures all phase bits in parallel using multiple ancilla qubits.

References

Nielsen, M. A., & Chuang, I. L. (2010). [NC10]

class qdk_chemistry.plugins.qiskit.standard_phase_estimation.QiskitStandardPhaseEstimation(num_bits=-1, evolution_time=0.0, qft_do_swaps=True, shots=3)[source]

Bases: PhaseEstimation

Standard QFT-based (non-iterative) phase estimation.

Parameters:

num_bits (int)
evolution_time (float)
qft_do_swaps (bool)
shots (int)

__init__(num_bits=-1, evolution_time=0.0, qft_do_swaps=True, shots=3)[source]

Initialize the Qiskit standard phase estimation routine.

Parameters:

num_bits (int) – The number of phase bits to estimate. Default to -1; user needs to set a valid value.
evolution_time (float) – Time parameter t used in the time-evolution unitary U = exp(-i H t), defaults to 0.0; user needs to set a valid value.
qft_do_swaps (bool) – Whether to include the final swap layer in the inverse QFT. Defaults to True so that the measured bit string is ordered from most-significant to least-significant bit.
shots (int) – The number of shots to execute the circuit.

create_circuit(state_preparation, qubit_hamiltonian, *, evolution_builder, circuit_mapper)[source]

Build the standard QPE circuit.

Return type:

Circuit

Parameters:

state_preparation (Circuit) – The circuit that prepares the initial state.
qubit_hamiltonian (QubitHamiltonian) – The qubit Hamiltonian for which to estimate the phase.
evolution_builder (TimeEvolutionBuilder) – The time evolution builder to use.
circuit_mapper (ControlledEvolutionCircuitMapper) – The controlled evolution circuit mapper to use.

Returns:

The constructed QPE quantum circuit.

get_circuit()[source]

Get the QPE circuit generated during algorithm execution.

Return type:: Circuit
Returns:: The quantum circuit used in the last execution.
Raises:: ValueError – If no QPE circuit is available.

name()[source]

Return the algorithm name as qiskit_standard.

Return type:: str

class qdk_chemistry.plugins.qiskit.standard_phase_estimation.QiskitStandardPhaseEstimationSettings[source]

Bases: PhaseEstimationSettings

Settings for the Qiskit Standard Phase Estimation algorithm.

__init__()[source]

Initialize the settings for Qiskit Standard Phase Estimation.

Parameters:

qft_do_swaps – Whether to include the final swap layer in the inverse QFT.
shots – The number of shots to execute the circuit.