Deutsch–Jozsa algorithm
With the promise that a function is constant or balanced, decide which using one quantum query.
Back to learning pathQuantum algorithmsWhy this experiment matters
What you will do
Use interference to see a simple, exact example of quantum query advantage.
- 01
Prepare two input qubits in |+⟩ and one auxiliary qubit in |−⟩.
- 02
Query the promised reversible oracle once and use phase kickback.
- 03
Interfere the paths and measure the two input qubits.
04 · PREDICT
Predict before you measure
Choose one answer to unlock the measurement.
INTERACTIVE
Interactive model
Move the control, then run a measurement. This is a teaching simulation—not hardware output.
Make a prediction, then run the measurement to reveal the expected and sampled results.
Measurement results
What the result shows
Input result 00 means constant; any nonzero two-bit result means balanced. In the ideal circuit the answer is exact.
GUIDED VIDEO
Watch the experiment
Follow the experiment with English narration and English subtitles.
Use interference to see a simple, exact example of quantum query advantage.
Full transcript5 · 1:00
- 01Overview
Use interference to see a simple, exact example of quantum query advantage.
- 02Experiment steps 1
Prepare two input qubits in |+⟩ and one auxiliary qubit in |−⟩.
- 03Experiment steps 2
Query the promised reversible oracle once and use phase kickback.
- 04Experiment steps 3
Interfere the paths and measure the two input qubits.
- 05What to observe
Input result 00 means constant; any nonzero two-bit result means balanced. In the ideal circuit the answer is exact.
06 · CHECK
Check what you learned
Make a prediction, then run the measurement to reveal the expected and sampled results.