Measurement and shots
Separate theoretical probabilities from observed frequencies.
Intuition
One shot is one preparation-and-measurement experiment. To collect another shot, prepare the state again. More shots usually make the observed frequencies closer to the probabilities, not exactly equal.
Prepare |+⟩ and run 10, 100, and 10,000 shots. In Measurements, counts fluctuate. In Probabilities, the ideal values stay at 50%. The lab displays the state before terminal measurement, not the collapsed state from one shot.
The mathematics
Look a little deeper
A computational-basis measurement of a pure single qubit leaves |0⟩ or |1⟩ conditional on the outcome. Repeatedly measuring that same collapsed state is not the same as repeating the full preparation experiment.
Use it
Prepare |+⟩ using one gate, then compare shot counts. Measurement is added automatically by this lab.
This exercise uses the same server-side state and circuit checks as its linked practice problem.
Build your circuit
Click a gate to append it, or drag it onto a wire. CX uses the selected control; SWAP uses it as the second operand. Basis order: |qₙ … q₀⟩.
Returned logical circuit · before transpilation · q0 on top
Connect to code
qc.h(0) qc.measure_all()
These operations go inside a circuit-building program. Practice problems provide a complete solve() template.
Check your understanding
First complete the circuit exercise successfully.