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Qiskit / qiskit-aer

Aer is a high performance simulator for quantum circuits that includes noise models
https://qiskit.github.io/qiskit-aer/
Apache License 2.0
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Aer Estimator fails on parameter binding when executing complex circuits #1816

Closed adekusar-drl closed 1 year ago

adekusar-drl commented 1 year ago

Informations

What is the current behavior?

Aer Estimator fails on complex circuits when reference Estimator works well.

A similar issue is filed here: https://github.com/Qiskit/qiskit-ibm-runtime/issues/809, I think they are related, but the circuit in that issue can be executed by Aer Estimator.

The Sampler primitive is subject to the same problem, I think.

Steps to reproduce the problem

Run the script:

import numpy as np
from qiskit import QuantumCircuit
from qiskit.circuit import ParameterVector
from qiskit.circuit.library import ZZFeatureMap
from qiskit.primitives import Estimator
from qiskit.quantum_info import Pauli
from qiskit_aer.primitives import Estimator as AerEstimator

def create_layer(num_qubits, params):
    qc = QuantumCircuit(num_qubits, name="L")

    param_index = 0
    for qubit1 in range(0, num_qubits - 1, 2):
        qubit2 = qubit1 + 1
        unit_params = params[param_index: param_index + 3]
        add_units(qc, qubit1, qubit2, unit_params)
        param_index += 3

    qc.barrier()

    for qubit1 in range(1, num_qubits - 1, 2):
        qubit2 = qubit1 + 1
        unit_params = params[param_index: param_index + 3]
        add_units(qc, qubit1, qubit2, unit_params)
        param_index += 3

    qc.barrier()

    return qc.to_instruction()

def add_units(qc: QuantumCircuit, qubit1, qubit2, params):
    u = QuantumCircuit(2, name="CXU")

    u.rz(params[0], 0)
    u.ry(params[1], 1)
    u.ry(params[2], 1)

    qc.compose(u.to_instruction(), [qubit1, qubit2], inplace=True)

def create_ansatz(num_qubits):

    qc = QuantumCircuit(num_qubits)

    num_params = 9
    params = ParameterVector("u", num_params)
    layer = create_layer(num_qubits, params)

    qc.compose(layer, list(range(num_qubits)), inplace=True)

    return qc

num_qubits = 4
fm = ZZFeatureMap(num_qubits)

ansatz = create_ansatz(num_qubits)

qc = QuantumCircuit(num_qubits)
qc.compose(fm, inplace=True)
qc.compose(ansatz, inplace=True)
print(qc)

# qc = qc.decompose(reps=3)

estimator = Estimator()
result = estimator.run(qc, Pauli("Z" * num_qubits), np.random.random(qc.num_parameters)).result()
print(f"Reference: {result}")

estimator = AerEstimator()
result = estimator.run(qc, Pauli("Z" * num_qubits), np.random.random(qc.num_parameters)).result()
print(f"Aer: {result}")

I get a stack trace:

Simulation failed and returned the following error message:
ERROR: Failed to load circuits: Invalid parameterized qobj: instruction param position out of range
Traceback (most recent call last):
  File ".../__aer_estimator_bug.py", line 73, in <module>
    result = estimator.run(qc, Pauli("Z" * num_qubits), np.random.random(qc.num_parameters)).result()
  File ".../python3.8/site-packages/qiskit/primitives/primitive_job.py", line 55, in result
    return self._future.result()
  File ".../python3.8/concurrent/futures/_base.py", line 444, in result
    return self.__get_result()
  File ".../python3.8/concurrent/futures/_base.py", line 389, in __get_result
    raise self._exception
  File ".../python3.8/concurrent/futures/thread.py", line 57, in run
    result = self.fn(*self.args, **self.kwargs)
  File ".../python3.8/site-packages/qiskit_aer/primitives/estimator.py", line 119, in _call
    return self._compute(circuits, observables, parameter_values, run_options)
  File ".../python3.8/site-packages/qiskit_aer/primitives/estimator.py", line 229, in _compute
    expectation_values, metadata = zip(
  File ".../python3.8/site-packages/qiskit_aer/primitives/estimator.py", line 230, in <genexpr>
    *(post_processing.run(results) for post_processing in post_processings)
  File ".../python3.8/site-packages/qiskit_aer/primitives/estimator.py", line 486, in run
    result = results[c_i]
IndexError: list index out of range

If the line # qc = qc.decompose(reps=3) is uncommented, I get a slightly different error that might shed a light on the problem. Here is this stack trace:

Traceback (most recent call last):
  File ".../python3.8/site-packages/qiskit/circuit/parameterexpression.py", line 474, in __float__
    return float(self._symbol_expr)
  File "symengine_wrapper.pyx", line 1151, in symengine.lib.symengine_wrapper.Basic.__float__
  File "symengine_wrapper.pyx", line 976, in symengine.lib.symengine_wrapper.Basic.n
  File "symengine_wrapper.pyx", line 4346, in symengine.lib.symengine_wrapper.evalf
RuntimeError: Symbol cannot be evaluated.

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File ".../__aer_estimator_bug.py", line 73, in <module>
    result = estimator.run(qc, Pauli("Z" * num_qubits), np.random.random(qc.num_parameters)).result()
  File ".../python3.8/site-packages/qiskit/primitives/primitive_job.py", line 55, in result
    return self._future.result()
  File ".../python3.8/concurrent/futures/_base.py", line 444, in result
    return self.__get_result()
  File ".../python3.8/concurrent/futures/_base.py", line 389, in __get_result
    raise self._exception
  File ".../python3.8/concurrent/futures/thread.py", line 57, in run
    result = self.fn(*self.args, **self.kwargs)
  File ".../python3.8/site-packages/qiskit_aer/primitives/estimator.py", line 119, in _call
    return self._compute(circuits, observables, parameter_values, run_options)
  File ".../python3.8/site-packages/qiskit_aer/primitives/estimator.py", line 217, in _compute
    self._backend.run(
  File ".../python3.8/site-packages/qiskit_aer/jobs/utils.py", line 41, in _wrapper
    return func(self, *args, **kwargs)
  File ".../python3.8/site-packages/qiskit_aer/jobs/aerjob.py", line 106, in result
    return self._future.result(timeout=timeout)
  File ".../python3.8/concurrent/futures/_base.py", line 437, in result
    return self.__get_result()
  File ".../python3.8/concurrent/futures/_base.py", line 389, in __get_result
    raise self._exception
  File ".../python3.8/concurrent/futures/thread.py", line 57, in run
    result = self.fn(*self.args, **self.kwargs)
  File ".../python3.8/site-packages/qiskit_aer/backends/aerbackend.py", line 437, in _execute_circuits_job
    aer_circuits = assemble_circuits(circuits)
  File ".../python3.8/site-packages/qiskit_aer/backends/aer_compiler.py", line 552, in assemble_circuits
    return [assemble_circuit(circuit) for circuit in circuits]
  File ".../python3.8/site-packages/qiskit_aer/backends/aer_compiler.py", line 552, in <listcomp>
    return [assemble_circuit(circuit) for circuit in circuits]
  File ".../python3.8/site-packages/qiskit_aer/backends/aer_compiler.py", line 376, in assemble_circuit
    global_phase = float(circuit.global_phase)
  File ".../python3.8/site-packages/qiskit/circuit/parameterexpression.py", line 477, in __float__
    raise TypeError(
TypeError: ParameterExpression with unbound parameters ({ParameterVectorElement(u[0]), ParameterVectorElement(u[6]), ParameterVectorElement(u[3])}) cannot be cast to a float.

What is the expected behavior?

No error is risen.

hhorii commented 1 year ago

Thank you for your reporting. Please try the latest main branch because https://github.com/Qiskit/qiskit-aer/commit/269fbce8ef659a951c7a471d21237e3aa549be38 fixes this issue.

adekusar-drl commented 1 year ago

Updated my environment to Aer from the sources. The problem is still there. If I uncomment # qc = qc.decompose(reps=3) the issue is still the same. Unfortunately, I cannot reopen this issue.