Skip to content

Ensure the result of simulation is normalized #6522

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom
Merged
NoureldinYosri merged 6 commits into from
Apr 3, 2024
Merged

Ensure the result of simulation is normalized #6522

NoureldinYosri merged 6 commits into from
Apr 3, 2024

Conversation

@NoureldinYosri
Copy link
Collaborator

@NoureldinYosri NoureldinYosri commented Mar 22, 2024 •
edited
Loading

@NoureldinYosri NoureldinYosri requested review from a team, cduck and vtomole as code owners March 22, 2024 23:08
@NoureldinYosri NoureldinYosri requested a review from dabacon March 22, 2024 23:08
@codecov
Copy link

codecov bot commented Mar 22, 2024 •
edited
Loading

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.78%. Comparing base (f955650) to head (7856e81).
Report is 1 commits behind head on main.

❗ Current head 7856e81 differs from pull request most recent head 9aac89e. Consider uploading reports for the commit 9aac89e to get more accurate results

Additional details and impacted files 
@@            Coverage Diff             @@
##             main    #6522      +/-   ##
==========================================
- Coverage   97.78%   97.78%   -0.01%     
==========================================
  Files        1107     1105       -2     
  Lines       95182    95113      -69     
==========================================
- Hits        93073    93004      -69     
  Misses       2109     2109

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

daxfohl
daxfohl reviewed Mar 23, 2024
View reviewed changes
@daxfohl
Copy link
Collaborator

daxfohl commented Mar 23, 2024

I considered doing this in the past when the earlier issue came up, but was concerned it was like sweeping dirt under the rug. Does doing this then make other invariants start failing? I think it's worth looking at what other projects do here, and try to follow prior art on the subject.

@NoureldinYosri
Copy link
Collaborator Author

NoureldinYosri commented Mar 25, 2024

@daxfohl for state vector there is not an issue

for density matrix it doesn't work (I reverted my changes and restricted this PR to state vector simulation). the invariant of density matrix is that $Tr[\rho^2] \leq 1$ with equality if and only if $\rho$ is pure. I don't think we should implicitly add the computation $Tr[\rho^2]$

pavoljuhas
pavoljuhas reviewed Mar 26, 2024
View reviewed changes
cirq-core/cirq/sim/state_vector_simulator.py Outdated
Comment on lines 127 to 128
ret = self._get_merged_sim_state().target_tensor.reshape(-1)
return ret / np.linalg.norm(ret)
Copy link
Collaborator

@pavoljuhas pavoljuhas Mar 26, 2024

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Can we raise UserWarning if abs(norm(state_vector) - 1) > np.sqrt(np.finfo(state_vector.dtype).eps)?

That should be sufficient for an accumulated round off from ~1/eps operations, but give some warning in case the state vector would be widely off.

pavoljuhas
pavoljuhas reviewed Mar 26, 2024
View reviewed changes
Copy link
Collaborator

@pavoljuhas pavoljuhas left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think we should have some check here so we don't re-normalize incorrect state vector.

@NoureldinYosri NoureldinYosri enabled auto-merge (squash) April 2, 2024 23:53
@NoureldinYosri NoureldinYosri merged commit 45c5fa3 into main Apr 3, 2024
@pavoljuhas pavoljuhas mentioned this pull request Apr 9, 2024
Merged
pavoljuhas added a commit to pavoljuhas/Cirq that referenced this pull request Apr 9, 2024
@pavoljuhas
Avoid state vector normalization if it worsens the round offs
43cb287 
This fixes failure of

check/pytest -n0 cirq-core/cirq/circuits/circuit_test.py::test_final_state_vector

which happened because normalization of a state vector at `np.complex64`
precision can subtly increase the overall round-off error.

Follow up to quantumlib#6522 and quantumlib#6402
pavoljuhas added a commit that referenced this pull request Apr 10, 2024
@pavoljuhas
Avoid state vector normalization if it worsens the round offs (#6556)
d16b12c 
This fixes failure of

check/pytest -n0 cirq-core/cirq/circuits/circuit_test.py::test_final_state_vector

which happened because normalization of a state vector at `np.complex64`
precision can subtly increase the overall round-off error.

Follow up to #6522 and #6402
jselig-rigetti pushed a commit to jselig-rigetti/Cirq that referenced this pull request May 28, 2024
@NoureldinYosri @jselig-rigetti
Ensure the result of simulation is normalized (quantumlib#6522)
0162147
jselig-rigetti pushed a commit to jselig-rigetti/Cirq that referenced this pull request May 28, 2024
@pavoljuhas @jselig-rigetti
Avoid state vector normalization if it worsens the round offs (quantu…
3bc6d97 
…mlib#6556)

This fixes failure of

check/pytest -n0 cirq-core/cirq/circuits/circuit_test.py::test_final_state_vector

which happened because normalization of a state vector at `np.complex64`
precision can subtly increase the overall round-off error.

Follow up to quantumlib#6522 and quantumlib#6402
harry-phasecraft pushed a commit to PhaseCraft/Cirq that referenced this pull request Oct 31, 2024
@NoureldinYosri
Ensure the result of simulation is normalized (quantumlib#6522)
2699e22
harry-phasecraft pushed a commit to PhaseCraft/Cirq that referenced this pull request Oct 31, 2024
@pavoljuhas
Avoid state vector normalization if it worsens the round offs (quantu…
e2ce245 
…mlib#6556)

This fixes failure of

check/pytest -n0 cirq-core/cirq/circuits/circuit_test.py::test_final_state_vector

which happened because normalization of a state vector at `np.complex64`
precision can subtly increase the overall round-off error.

Follow up to quantumlib#6522 and quantumlib#6402
@pavoljuhas pavoljuhas deleted the normalize_final_results branch January 22, 2025 07:30
BichengYing pushed a commit to BichengYing/Cirq that referenced this pull request Jun 20, 2025
@pavoljuhas @BichengYing
Avoid state vector normalization if it worsens the round offs (quantu…
363dfc4 
…mlib#6556)

This fixes failure of

check/pytest -n0 cirq-core/cirq/circuits/circuit_test.py::test_final_state_vector

which happened because normalization of a state vector at `np.complex64`
precision can subtly increase the overall round-off error.

Follow up to quantumlib#6522 and quantumlib#6402
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

@daxfohl daxfohl daxfohl left review comments

@pavoljuhas pavoljuhas pavoljuhas approved these changes

@vtomole vtomole Awaiting requested review from vtomole vtomole is a code owner

@cduck cduck Awaiting requested review from cduck

@dabacon dabacon Awaiting requested review from dabacon dabacon is a code owner automatically assigned from quantumlib/cirq-maintainers

Assignees

No one assigned

Labels

None yet

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

3 participants

@NoureldinYosri @daxfohl @pavoljuhas