# How to Correctly Measure All Qubits in a Quantum Circuit?

Description: I'm currently working on a project that involves running quantum circuits as a hybrid job on the aws tensor network simulator 'tn1'.

Error on the Cloudwatch logs:An error occurred while executing the quantum circuit: 'list' object has no attribute 'measure_all'

how i execute circuits:

def execute_quantum_circuit(circuit, shots=1000):
try:
backend = AWSBraketProvider().get_backend("TN1")
circuit.measure_all()
job = backend.run(circuit, shots=shots)
result = job.result()
counts = result.get_counts()

return counts
except Exception as e:
print(f"An error occurred while executing the quantum circuit: {e}")
return None


how I create the the Grover oracle:

def create_grover_oracle(address, num_qubits):
try:
qr = QuantumRegister(num_qubits)
oracle_circuit = QuantumCircuit(qr)

# apply hadamard gates to create a uniform superposition
oracle_circuit.h(qr)

if bit == '1':
oracle_circuit.x(i)

# apply controlled-Z gates to mark the solution(s)
ancilla = QuantumRegister(1)
oracle_circuit.h(ancilla)
if bit == '1':
oracle_circuit.cz(i, ancilla[0])

# multi-controlled-Z gate
oracle_circuit.h(qr)
oracle_circuit.mcx(qr[:-1], qr[-1])
oracle_circuit.h(qr)

# uncompute the encoding by applying X gates again
if bit == '1':
oracle_circuit.x(i)

# apply hadamard gates again to maintain superposition
oracle_circuit.h(qr)

return oracle_circuit
except Exception as e:
print(f"An error occurred while creating the Grover oracle: {e}")
return None


how I create the diffusion circuit:

def create_diffusion_circuit(num_qubits):
try:
qr = QuantumRegister(num_qubits)
diffusion_circuit = QuantumCircuit(qr)

# apply hadamard gates to create a uniform superposition
diffusion_circuit.h(qr)

# apply X gates to prepare for multi-controlled Z gate
diffusion_circuit.x(qr)

# multi-controlled Z gate
diffusion_circuit.h(qr[-1])
diffusion_circuit.mct(qr[:-1], qr[-1])
diffusion_circuit.h(qr[-1])

# apply X gates again
diffusion_circuit.x(qr)

diffusion_circuit.h(qr)

# optimize gate sequences in the diffusion circuit
optimized_diffusion_circuit = optimize_gates(diffusion_circuit)

return optimized_diffusion_circuit


the call functions:

oracle_partition = create_grover_oracle(correct_address, num_qubits=50)
diffusion_circuit = create_diffusion_circuit(num_qubits=50)
counts = execute_quantum_circuit(oracle_partition)
execute_quantum_circuit(diffusion_circuit)


the optimise circuit def:

def optimize_gates(circuit):
try:
optimized_circuit = QuantumCircuit(circuit.num_qubits)

# Iterate through the gates in the circuit
i = 0
while i < len(circuit.data) - 1:
current_gate = circuit.data[i]
next_gate = circuit.data[i + 1]

# Check if both gates are instances of Gate
if isinstance(current_gate[0], Gate) and isinstance(next_gate[0], Gate):
# Check if the gates are of the same type and act on the same qubits
if current_gate[0].name == next_gate[0].name and current_gate[1] == next_gate[1]:
# Combine consecutive gates into a single gate
combined_gate = current_gate[0].compose(next_gate[0], qubits=current_gate[1])

# Append the combined gate to the optimized circuit
optimized_circuit.append(combined_gate, current_gate[1])

# Move to the gate after the next gate
i += 2
else:
# Append the current gate to the optimized circuit
optimized_circuit.append(current_gate[0], current_gate[1])

# Move to the next gate
i += 1
else:
# Append the current gate to the optimized circuit
optimized_circuit.append(current_gate[0], current_gate[1])

# Move to the next gate
i += 1

# If there's one gate left after the loop, append it to the optimized circuit
if i == len(circuit.data) - 1:
last_gate = circuit.data[-1]
optimized_circuit.append(last_gate[0], last_gate[1])

return optimized_circuit


Need assistance:

I would appreciate any insights or guidance on how to properly measure all the qubits so i can get the measurement counts, as well as any suggestions for the implementation of grovers algorithm.

P.S.: I previously was getting 0s in the measurement counts so i reimplemented the circuit defs

• Hi @Neel! In order to answer you exactly, more code is needed. You provide the definition of execute_quantum_circuit but we have no idea how/where you call it. Also, according to the error, you likely give a list as first parameter of execute_quantum_circuit when you call it. Feb 29 at 15:25
• @AdrienSuau oracle_partition = create_grover_oracle(correct_address, num_qubits=50) diffusion_circuit = create_diffusion_circuit(num_qubits=50) counts = execute_quantum_circuit(oracle_partition) execute_quantum_circuit(diffusion_circuit)
– Neel
Feb 29 at 15:54
• The optimize_gates likely returns a list. You should edit your question to include the code above and to include the definition / import of the optimize_gates function you call in create_diffusion_circuit. Feb 29 at 16:09
• @AdrienSuau another thing the last thing the log shows is this and then nothing infinetly INFO:qiskit.passmanager.base_tasks:Pass: ContainsInstruction - 0.02599 (ms) INFO:qiskit.passmanager.base_tasks:Pass: UnitarySynthesis - 0.02003 (ms) how can i debug this there is no traceback and stuff
– Neel
Feb 29 at 17:09
• @AdrienSuau and how to properly measure all the qubits in the execute def and get counts
– Neel
Feb 29 at 17:28