Measurement¶

Overview¶

Measurement records qubit values into classical bits so you can retrieve results after execution.

This page describes how to add measurement operations to a circuit and how to read shot results and aggregated counts from the job result.

For the end-to-end flow (provider → backend → circuit → run), see Circuits. For execution options such as shots, see Run Settings.

Add measurement to a circuit¶

Measure a single qubit¶

Use qc.measure(qubit, classical_bit) to project a qubit into a classical bit.

from QuantumRingsLib import QuantumCircuit

qc = QuantumCircuit(2, 2)
qc.h(0)
qc.measure(0, 0)

Measure all qubits¶

Use qc.measure_all() to add in-place measurement to all qubits. Projections are made to the corresponding classical bits. Classical bits are added if required.

qc = QuantumCircuit(2, 2)
qc.h(0)
qc.cx(0, 1)
qc.measure_all()

Measure active qubits¶

Use qc.measure_active() to add in-place measurement to all non-idle qubits. Projections are made to the corresponding classical bits. Classical bits are added if required.

Run and read results¶

After calling backend.run(...), use job.result() to retrieve a Result object.

Two common ways to read measurement output are:

result.get_memory() — returns measurement data for all shots as a list of strings.
result.get_counts() — returns a dictionary of outcomes, where the value is the percentage of occurrence for each measurement result.

from QuantumRingsLib import QuantumCircuit, QuantumRingsProvider

provider = QuantumRingsProvider()
backend = provider.get_backend("scarlet_quantum_rings")

qc = QuantumCircuit(2, 2)
qc.h(0)
qc.cx(0, 1)
qc.measure_all()

job = backend.run(qc, shots=100)
result = job.result()

memory = result.get_memory()
counts = result.get_counts()

print(memory[:10])
print(counts)