Enable pulling through Clifford operations, also add an option of only applying dd to single qubit gate moments #6675

babacry · 2024-07-24T06:40:52Z

Enable adding dynamical decoupling in single qubit gate moments only.

Adding mechanism is described in the code. In short:

For each qubit:
      For moments in (first_active_moment, last_active_single_qubit_moment):
            Insert
      Absorb the inverse to the last_active_single_qubit_moment

2 test cases added for single qubit gates moments insertion mode:

Test case 1: add dd preserves the circuit.

0: ───────────────────────────────H───@───
                                      │
1: ───────────────────────H───@───H───X───
                              │
2: ───────────────H───@───H───X───────────
                      │
3: ───H───────@───H───X───────────────────
              │
4: ───H───@───X───────────────────────────
          │
5: ───H───X───────H───@───────────────────
                      │
6: ───────────────H───X───H───@───────────
                              │
7: ───────────────────────H───X───H───@───
                                      │
8: ───────────────────────────────H───X───

Test case 2:

input_circuit's diagram is:

0: ───────────────────────────────H───@───H───
                                      │
1: ───────────────────────H───@───H───X───H───
                              │
2: ───────────────H───@───H───X───────────H───
                      │
3: ───H───────@───H───X───────────────────H───
              │
4: ───H───@───X───────────────────────────H───
          │
5: ───H───X───────H───@───────────────────H───
                      │
6: ───────────────H───X───H───@───────────H───
                              │
7: ───────────────────────H───X───H───@───H───
                                      │
8: ───────────────────────────────H───X───H───

output diagram is

0: ───────────────────────────────H───@───H────────────────────────
                                      │
1: ───────────────────────H───@───H───@───H────────────────────────
                              │
2: ───────────────H───@───H───@───X───────PhXZ(a=-0.5,x=0.5,z=0)───
                      │
3: ───H───────@───H───@───X───────X───────H────────────────────────
              │
4: ───H───@───@───X───────X───────X───────PhXZ(a=-0.5,x=0.5,z=0)───
          │
5: ───H───@───────H───@───X───────X───────H────────────────────────
                      │
6: ───────────────H───@───H───@───X───────PhXZ(a=-0.5,x=0.5,z=0)───
                              │
7: ───────────────────────H───@───H───@───H────────────────────────
                                      │
8: ───────────────────────────────H───@───H────────────────────────

codecov · 2024-07-24T18:47:27Z

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.83%. Comparing base (e2e8aef) to head (74305a0).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff            @@
##             main    #6675    +/-   ##
========================================
  Coverage   97.83%   97.83%            
========================================
  Files        1075     1077     +2     
  Lines       92325    92493   +168     
========================================
+ Hits        90324    90492   +168     
  Misses       2001     2001

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

eliottrosenberg

I think the following logic would be useful to test the correctness of the final circuits:

sampler = cirq.Simulator(dtype=np.complex128)
psi0 = sampler.simulate(circuit).final_state_vector
psi1 = sampler.simulate(transformed_circuit).final_state_vector
assert np.isclose(np.abs(np.vdot(psi0, psi1))**2, 1.0)

In particular, if this is the original circuit:

0: ───────────────────────────────────H───@───H───H───
                                          │
1: ───────────────────────────H───@───H───@───────H───
                                  │
2: ───────────────────H───@───H───@───────────────H───
                          │
3: ───────────H───@───H───@───────────────────────H───
                  │
4: ───H───@───────@───────────────────────────────H───
          │
5: ───H───@───H───@───────────────────────────────H───
                  │
6: ───────────H───@───H───@───────────────────────H───
                          │
7: ───────────────────H───@───H───@───────────────H───
                                  │
8: ───────────────────────────H───@───H───@───────H───
                                          │
9: ───────────────────────────────────H───@───H───H───

Then with schema='X_XINV' and single_qubit_gate_moments_only=True, it gets transformed to

0: ───────────────────────────────────H───@───H───H────────────────────────
                                          │
1: ───────────────────────────H───@───H───@───X───PhXZ(a=-0.5,x=0.5,z=0)───
                                  │
2: ───────────────────H───@───H───@───X───────X───H────────────────────────
                          │
3: ───────────H───@───H───@───X───────X───────X───PhXZ(a=-0.5,x=0.5,z=0)───
                  │
4: ───H───@───X───@───X───────X───────X───────X───PhXZ(a=-0.5,x=0.5,z=0)───
          │
5: ───H───@───H───@───X───────X───────X───────X───H────────────────────────
                  │
6: ───────────H───@───H───@───X───────X───────X───PhXZ(a=-0.5,x=0.5,z=0)───
                          │
7: ───────────────────H───@───H───@───X───────X───H────────────────────────
                                  │
8: ───────────────────────────H───@───H───@───X───PhXZ(a=-0.5,x=0.5,z=0)───
                                          │
9: ───────────────────────────────────H───@───H───H────────────────────────

which fails this test.

If I try the same transformation with single_qubit_gate_moments_only=False, then I get the following circuit

0: ───────X───X───X───X───X───X───────H───@───H───H───
                                          │
1: ───────X───X───X───X───────H───@───H───@───────H───
                                  │
2: ───────X───X───────H───@───H───@───X───X───────H───
                          │
3: ───────────H───@───H───@───X───X───X───X───────H───
                  │
4: ───H───@───────@───X───X───X───X───X───X───────H───
          │
5: ───H───@───H───@───X───X───X───X───X───X───────H───
                  │
6: ───────────H───@───H───@───X───X───X───X───────H───
                          │
7: ───────X───X───────H───@───H───@───X───X───────H───
                                  │
8: ───────X───X───X───X───────H───@───H───@───────H───
                                          │
9: ───────X───X───X───X───X───X───────H───@───H───H───

which doesn't quite behave as expected; many qubits could fit two more cirq.X gates. (Also the more ideal behavior would be to not add any DD gates prior to the first moment that acts on that qubit.)

eliottrosenberg · 2024-07-26T06:12:55Z

I suspect that the bug is in the logic of how to pull Pauli gates through Clifford gates (e.g. cirq.CZ)

babacry · 2024-07-31T21:53:31Z

For single-qubit-gate moments insertion only: the bug was fixed in this commit. And it was tested via

cirq.testing.assert_circuits_have_same_unitary_given_final_permutation(
        input_circuit, transformed_circuit, {q: q for q in input_circuit.all_qubits()}
    )

and

sampler = cirq.Simulator(dtype=np.complex128)
psi0 = sampler.simulate(input_circuit).final_state_vector
psi1 = sampler.simulate(transformed_circuit).final_state_vector
assert np.isclose(np.abs(np.vdot(psi0, psi1)) ** 2, 1.0)

both passed for all test cases.

For non-single-qubit-gate moments insertion, there are 2 issues
- op wasn't inserted from first active moment, it's fixed in the latest commit.
- Now, we fill in operations in consecutive idle pieces only, while I am not sure what is the expected transformed circuit for the following cases.

Input circuit:

a: ───H───@───────?───────────────H───
          │
b: ───────X───@───@───@───@───@───H───
              │   │   │   │   │
c: ───────────X───X───X───X───X───H───

where ? can be any single-qubit-gate, e.g., X / H.

Transformed circuit with schema="XX_PAIR"
- Current code would transform the circuit into as for a, the idle pieces lengths are 1, 3

a: ───H───@───────?───X───X───────H───
          │
b: ───────X───@───@───@───@───@───H───
              │   │   │   │   │
c: ───────────X───X───X───X───X───H───

Is this expected? I suspect we can't commute through the moment ? at due to non commutativity, right? or should we take care of ? case by case? for example, if ?=X, then, we can add 2 more X gates for qubit a in the transformed circuit above. while, '?=H', we can't insert more, right?

eliottrosenberg

LGTM!! (with one small nit)

Thank you so much, Renyi!

eliottrosenberg · 2024-08-13T23:35:59Z

cirq-core/cirq/transformers/dynamical_decoupling.py



 @transformer_api.transformer
 def add_dynamical_decoupling(
    circuit: 'cirq.AbstractCircuit',
    *,
    context: Optional['cirq.TransformerContext'] = None,
-    schema: Union[str, Sequence['cirq.Gate']] = 'X_XINV',
+    schema: Union[str, Tuple['cirq.Gate', ...]] = 'X_XINV',


Let's change the default schema to (cirq.X, cirq.Y, cirq.X, cirq.Y). I think that gives better performance experimentally.

eliottrosenberg

I noticed that if the circuit ends in a measurement, e.g.

0: ───────────H───@───H───M───
                  │       │
1: ───H───@───────@───────M───
          │               │
2: ───H───@───H───@───────M───
                  │       │
3: ───────────H───@───H───M───

then the transformer misbehaves. In this case, it outputs

0: ───────────H───@───H───M───X───
                  │       │
1: ───H───@───X───@───X───M───────
          │               │
2: ───H───@───H───@───X───M───X───
                  │       │
3: ───────────H───@───H───M───────

One option is to raise a NotImplementedError if the circuit contains measure gates. Alternatively, you could add support for circuits that include measure gates. (You can't pull single-qubit gates through measure gates, and no need to add DD unless there are more gates after the measure gate.)

Also enabling only apply dd to single qubit gates moments. Multiple test cases with diagrams in docstrings are added.

babacry · 2024-08-14T00:59:57Z

Now, we rely on cirq.has_stabilizer_effect to determine if an operation is Clifford. While, cirq.has_stabilizer_effect(cirq.M) returns True, resulting in a polluted clifford piece. Add a criteria for function _is_clifford_moment and the test case in the comment above.

babacry · 2024-08-14T01:25:10Z

Also changed default schema in the new commit.

eliottrosenberg

LGTM! Thank you, Renyi!

NoureldinYosri

is there a way to simplify this code?

The single qubit clifford algebra is implemented in the SingleQubitCliffordGate class this may help simplify the implementation

NoureldinYosri · 2024-08-14T16:36:00Z

cirq-core/cirq/transformers/dynamical_decoupling_test.py

+    )
+
+
+def test_exceptions():


I don't understand this test

Good catch, should delete this.

NoureldinYosri

merging now to unblock users but this code can probably be simplified

…y applying dd to single qubit gate moments (quantumlib#6675)

babacry requested review from vtomole, cduck and a team as code owners July 24, 2024 06:40

babacry requested a review from viathor July 24, 2024 06:40

CirqBot added the size: M 50< lines changed <250 label Jul 24, 2024

babacry mentioned this pull request Jul 24, 2024

Implement dynamical decoupling transformer #6582

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eliottrosenberg requested review from NoureldinYosri and eliottrosenberg July 24, 2024 22:02

babacry force-pushed the single_moments branch 2 times, most recently from 72ddf41 to 9368cd4 Compare July 25, 2024 21:15

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babacry marked this pull request as draft August 6, 2024 20:24

babacry force-pushed the single_moments branch from c462170 to a80c9b7 Compare August 13, 2024 08:17

babacry marked this pull request as ready for review August 13, 2024 17:55

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babacry added 3 commits August 13, 2024 16:59

Pull Pauli gates through Clifford operations in dd.

40d48ec

Also enabling only apply dd to single qubit gates moments. Multiple test cases with diagrams in docstrings are added.

Fix an outdated docstring

efce59f

Treat measurement gates as non Clifford.

7aad4e9

babacry force-pushed the single_moments branch from a80c9b7 to 7aad4e9 Compare August 14, 2024 00:57

Change default schema to 'DEFAULT' (X, Y, X, Y).

f10f45d

babacry requested a review from eliottrosenberg August 14, 2024 01:25

Format

5fa81d5

babacry force-pushed the single_moments branch from 1a074c6 to 5fa81d5 Compare August 14, 2024 01:30

eliottrosenberg approved these changes Aug 14, 2024

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Merge branch 'main' into single_moments

adb0857

NoureldinYosri reviewed Aug 14, 2024

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babacry force-pushed the single_moments branch from 84faa14 to 2a7f563 Compare August 14, 2024 19:19

babacry changed the title ~~Enable only apply dd to single qubit gates moments~~ Enable pulling through Clifford operations, also add option of applying dd to single qubit gates moments Aug 14, 2024

babacry changed the title ~~Enable pulling through Clifford operations, also add option of applying dd to single qubit gates moments~~ Enable pulling through Clifford operations, also add an option of applying dd to single qubit gates moments Aug 14, 2024

babacry changed the title ~~Enable pulling through Clifford operations, also add an option of applying dd to single qubit gates moments~~ Enable pulling through Clifford operations, also add an option of only applying dd to single qubit gate moments Aug 14, 2024

Remove unnecessary tests

74305a0

babacry force-pushed the single_moments branch from 2a7f563 to 74305a0 Compare August 14, 2024 19:23

NoureldinYosri approved these changes Aug 14, 2024

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NoureldinYosri merged commit 8d8a6c5 into quantumlib:main Aug 14, 2024
34 checks passed

babacry deleted the single_moments branch September 5, 2024 01:44

harry-phasecraft pushed a commit to PhaseCraft/Cirq that referenced this pull request Oct 31, 2024

Enable pulling through Clifford operations, also add an option of onl…

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…y applying dd to single qubit gate moments (quantumlib#6675)

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Enable pulling through Clifford operations, also add an option of only applying dd to single qubit gate moments #6675

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Enable pulling through Clifford operations, also add an option of only applying dd to single qubit gate moments #6675

Enable pulling through Clifford operations, also add an option of only applying dd to single qubit gate moments #6675

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