Add validation to Sampler if there are no measurements

[ikkoham]

Summary

This PR resolves TODO comment in BaseSampler.

Details and comments

[qiskit-bot]

One or more of the the following people are requested to review this:

• @Qiskit/terra-core
• @ajavadia
• @ikkoham
• @levbishop
• @t-imamichi

[Cryoris]

That's a good check to have in place 👍🏻 Could you add a short releasenote for this, too?

[ikkoham]

Yes. I'll add a release note.

[coveralls]

Pull Request Test Coverage Report for Build 5921033642

• 12 of 12 (100.0%) changed or added relevant lines in 1 file are covered.
• 8 unchanged lines in 3 files lost coverage.
• Overall coverage increased (+0.03%) to 87.274%

---

Files with Coverage Reduction	New Missed Lines	%
qiskit/primitives/sampler.py	1	95.65%
qiskit/pulse/library/waveform.py	3	93.75%
crates/qasm2/src/lex.rs	4	91.14%

Totals
Change from base Build 5902014500:	0.03%
Covered Lines:	74376
Relevant Lines:	85221

---

💛 - Coveralls

[Cryoris]

LGTM, but I'm not sure it qualifies a bugfix and backport as this PR is technically an additional safety measure and not fixing a broken behavior. Is this something we need for 0.25.2 or is the next feature release enough?

[ikkoham]

@Cryoris Thank. Yes, you're right. This is not a feature bug fix, but I believe this is a error message bug or performance bug fix.
First, there were inappropriate error messages QiskitError: No counts for experiment \"0\" in qiskit-ibm-runtime. This PR improves a UX. Also, from another perspective, it should be meant to fix a performance bug, since errors before and after quantum computation execution consume very different amounts of resources.

[ikkoham]

This PR requires primitives team review. @t-imamichi or Mariana

[t-imamichi]

I investigated the history of circuit validation. I relaxed one in BaseSampler to support dynamic circuits (see #8708). Does this PR resolve the issue, perhaps?

[t-imamichi]

Details

I used to add a check of measurements #8678, but it was removed for mid-circuit measurement support in the future #8708. As a result, some Sampler implementations such as BackendSampler, Aer Sampler, and Runtime Sampler, raise an error when invoking job.result() as follows. This PR applies a check of measurement at run method to raise an error before submitting a job.

from qiskit import QuantumCircuit
from qiskit.primitives import Sampler, BackendSampler
from qiskit_aer import AerSimulator
from qiskit_aer.primitives import Sampler as AerSampler
from qiskit_ibm_runtime import Sampler as RuntimeSampler, QiskitRuntimeService, Session


qc = QuantumCircuit(1, 1)
qc.h(0)

if True:
    sampler = BackendSampler(backend=AerSimulator())
elif False:
    sampler = AerSampler()
else:
    service = QiskitRuntimeService(instance="ibm-q/open/main")
    backend = "ibmq_qasm_simulator"
    session = Session(service=service, backend=backend)
    sampler = RuntimeSampler(session=session)

job = sampler.run(qc, shots=100)
result = job.result()  # raise an error at result method
print(result)

output (main branch)

Traceback (most recent call last):
  File "/Users/ima/tasks/3_2023/qiskit/terra/tmp/sampler.py", line 22, in <module>
    result = job.result()
  File "/Users/ima/tasks/3_2023/qiskit/terra/qiskit/primitives/primitive_job.py", line 55, in result
    return self._future.result()
  File "/opt/homebrew/Cellar/python@3.10/3.10.12_1/Frameworks/Python.framework/Versions/3.10/lib/python3.10/concurrent/futures/_base.py", line 458, in result
    return self.__get_result()
  File "/opt/homebrew/Cellar/python@3.10/3.10.12_1/Frameworks/Python.framework/Versions/3.10/lib/python3.10/concurrent/futures/_base.py", line 403, in __get_result
    raise self._exception
  File "/opt/homebrew/Cellar/python@3.10/3.10.12_1/Frameworks/Python.framework/Versions/3.10/lib/python3.10/concurrent/futures/thread.py", line 58, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/Users/ima/tasks/3_2023/qiskit/terra/qiskit/primitives/backend_sampler.py", line 149, in _call
    return self._postprocessing(result, bound_circuits)
  File "/Users/ima/tasks/3_2023/qiskit/terra/qiskit/primitives/backend_sampler.py", line 154, in _postprocessing
    counts = _prepare_counts(result)
  File "/Users/ima/tasks/3_2023/qiskit/terra/qiskit/primitives/backend_estimator.py", line 79, in _prepare_counts
    count = res.get_counts()
  File "/Users/ima/tasks/3_2023/qiskit/terra/qiskit/result/result.py", line 289, in get_counts
    raise QiskitError(f'No counts for experiment "{repr(key)}"')
qiskit.exceptions.QiskitError: 'No counts for experiment "0"'

output with this PR

Traceback (most recent call last):
  File "/Users/ima/tasks/3_2023/qiskit/terra/tmp/sampler.py", line 21, in <module>
    job = sampler.run(qc, shots=100)
  File "/Users/ima/tasks/3_2023/qiskit/terra/qiskit/primitives/base/base_sampler.py", line 134, in run
    circuits = self._validate_circuits(circuits)
  File "/Users/ima/tasks/3_2023/qiskit/terra/qiskit/primitives/base/base_sampler.py", line 176, in _validate_circuits
    raise ValueError(
ValueError: The 0-th circuit does not have Measure instruction. Without measurements, the circuit cannot be sampled from.

[t-imamichi]

LGTM. But, let's wait for Mariana's review too.

[coveralls]

Pull Request Test Coverage Report for Build 5995648228

• 12 of 12 (100.0%) changed or added relevant lines in 1 file are covered.
• 35 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-0.04%) to 87.245%

---

Files with Coverage Reduction	New Missed Lines	%
qiskit/primitives/sampler.py	1	95.65%
crates/qasm2/src/lex.rs	4	91.14%
crates/qasm2/src/parse.rs	30	95.74%

Totals
Change from base Build 5985235181:	-0.04%
Covered Lines:	74265
Relevant Lines:	85122

---

💛 - Coveralls

[1ucian0]

i just saw the email of this closing. Is this PR related to #10706 ?

[t-imamichi]

No. This PR addresses a different issue.