Stateless `VQE` #6418

Cryoris · 2021-05-14T20:28:30Z

Summary

Closes #6380.

Details and comments

Refactor the VQE to become stateless.

Remove stateful internal properties
Deprecate stateful methods (like get_optimal_point)
Make the loss function, get_energy_evaluation publicly available

To do

Deprecate all stateful arguments
Maybe deprecate all methods except initial_state on VariationalAlgorithm

TODO deprecation

it doesn't really matter, having it None was more a safeguard, but adaptVQE breaks if this is None and not 0

qiskit/algorithms/minimum_eigen_solvers/qaoa.py

qiskit/algorithms/minimum_eigen_solvers/vqe.py

* deprecate sort_parameters_by_name * check ansatz has 0 params in setter * rename varform -> ansatz

meaning that if a user didn't set it, we re-construct the expectation for each new run of VQE

qiskit/algorithms/minimum_eigen_solvers/vqe.py

* make VQE stateless TODO deprecation * fix get initial point from ansatz * try fixing use of deprecate_function * fix tests & black * deprecate varalgo methods * sort params per circuit default * clarify deprecation message in varalgo.initialpoint * initialize eval_count with 0 instead of None it doesn't really matter, having it None was more a safeguard, but adaptVQE breaks if this is None and not 0 * simplify get_eigenstate * fix lint * remote note on parameter order * review suggestions * deprecate sort_parameters_by_name * check ansatz has 0 params in setter * rename varform -> ansatz * fix tests * lint * keep previous behaviour of expectation meaning that if a user didn't set it, we re-construct the expectation for each new run of VQE * move expectation factory to right place * address Qiskit#5746 * fix typehint in expectation (add Optional) * fix expectation setter Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

* make VQE stateless TODO deprecation * fix get initial point from ansatz * try fixing use of deprecate_function * fix tests & black * deprecate varalgo methods * sort params per circuit default * clarify deprecation message in varalgo.initialpoint * initialize eval_count with 0 instead of None it doesn't really matter, having it None was more a safeguard, but adaptVQE breaks if this is None and not 0 * simplify get_eigenstate * fix lint * remote note on parameter order * review suggestions * deprecate sort_parameters_by_name * check ansatz has 0 params in setter * rename varform -> ansatz * fix tests * lint * keep previous behaviour of expectation meaning that if a user didn't set it, we re-construct the expectation for each new run of VQE * move expectation factory to right place * address Qiskit/qiskit#5746 * fix typehint in expectation (add Optional) * fix expectation setter Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

Cryoris added 2 commits May 13, 2021 22:02

make VQE stateless

2eec21a

TODO deprecation

fix get initial point from ansatz

ce7e81d

Cryoris added the mod: algorithms Related to the Algorithms module label May 14, 2021

Cryoris added 5 commits May 16, 2021 17:45

try fixing use of deprecate_function

d6d3d81

Merge branch 'main' into stateless-vqe

8ca0d9a

fix tests & black

01ba50c

deprecate varalgo methods

eee0cd4

sort params per circuit default

ffd6b6d

Cryoris changed the title ~~[WIP] Stateless VQE~~ Stateless VQE Jun 1, 2021

Cryoris marked this pull request as ready for review June 1, 2021 08:38

Cryoris requested review from manoelmarques, woodsp-ibm and a team as code owners June 1, 2021 08:38

Cryoris added 2 commits June 3, 2021 13:40

clarify deprecation message in varalgo.initialpoint

480d2a3

initialize eval_count with 0 instead of None

4299347

it doesn't really matter, having it None was more a safeguard, but adaptVQE breaks if this is None and not 0

Cryoris mentioned this pull request Jun 3, 2021

Update AdaptVQE to new, stateless VQE qiskit-community/qiskit-nature#222

Merged

Cryoris added 4 commits June 3, 2021 17:29

Merge branch 'main' into stateless-vqe

fdad368

simplify get_eigenstate

06deb86

fix lint

070eb77

remote note on parameter order

a9b431b