Configuration recovery
qiskit_addon_sqd.configuration_recovery
Functions for performing self-consistent configuration recovery.
post_select_by_hamming_weight
post_select_by_hamming_weight(bitstring_matrix, *, hamming_right, hamming_left)
Post-select bitstrings based on the hamming weight of each half.
Parameters
- bitstring_matrix (ndarray) – A 2D array of
boolrepresentations of bit values such that each row represents a single bitstring - hamming_right (int) – The target hamming weight of the right half of bitstrings
- hamming_left (int) – The target hamming weight of the left half of bitstrings
Returns
A mask signifying which samples (rows) were selected from the input matrix.
Return type
recover_configurations
recover_configurations(bitstring_matrix, probabilities, avg_occupancies, num_elec_a, num_elec_b, rand_seed=None)
Refine bitstrings based on average orbital occupancy and a target hamming weight.
This function refines each bit in isolation in an attempt to transform the Hilbert space represented by the input bitstring_matrix into a space closer to that which supports the ground state.
This function makes the assumption that bit i represents the spin-down orbital corresponding to the spin-up orbital in bit i + N where N is the number of spatial orbitals and i < N.
Parameters
- bitstring_matrix (ndarray) – A 2D array of
boolrepresentations of bit values such that each row represents a single bitstring - probabilities (Sequence[float]) – A 1D array specifying a probability distribution over the bitstrings
- avg_occupancies (tuple[ndarray, ndarray]) – A length-2 tuple of arrays holding the mean occupancy of the spin-up and spin-down orbitals, respectively. The occupancies should be formatted as:
(array([occ_a_0, ..., occ_a_N]), array([occ_b_0, ..., occ_b_N])) - num_elec_a (int) – The number of spin-up electrons in the system.
- num_elec_b (int) – The number of spin-down electrons in the system.
- rand_seed (Generator |int | None) – A seed for controlling randomness
Returns
A refined bitstring matrix and an updated probability array.
Return type
References
[1]: J. Robledo-Moreno, et al., Chemistry Beyond Exact Solutions on a Quantum-Centric Supercomputer,
arXiv:2405.05068 [quant-ph].