ExperimentsExperiment 9 · Quantum search

Search Problems

Hidden number & database search with a pluggable oracle framework.

1. Learn
2. Watch
3. Interact
4. Predict
5. Run
6. Observe
7. Record
8. Answer
9. Research

① What is the problem?

How do real problems become Grover searches?

② How does a classical computer approach it?

Evaluate the check function on candidates until one passes.

③ How does the quantum approach differ?

Encode the check function as an oracle circuit that flips the phase of solutions, then run Grover.

A secret number between 0 and 63 is hidden. The only thing you can do is ask the oracle 'is it x?'.

Question

Which number between 0 and 63 is the secret?

Oracle predicate f(x) = 1 ⇔ x == 46

#10

#11

#12

#13

#14

#15

#16

#17

#18

#19

#20

#21

#22

#23

#24

#25

#26

#27

#28

#29

#30

#31

#32

#33

#34

#35

#36

#37

#38

#39

#40

#41

#42

#43

#44

#45

#46 ★

#47

#48

#49

#50

#51

#52

#53

#54

#55

#56

#57

#58

#59

#60

#61

#62

#63

Candidates

Qubits (2ⁿ ≥ N)

6 (64)

Classical checks (this run)

Grover oracle queries

…

P(solution)

…

The framework

Every problem implements SearchProblem: it generates candidates and a predicate f(x). The lab builds the oracle from f, runs Grover, and compares with a classical scan. In this simulator f is evaluated classically to build the oracle — on real hardware f must be compiled into a reversible quantum circuit, which is often the expensive part.

Planned problem types (not yet implemented)

🚧 3-SAT — planned
🚧 Sudoku — planned
🚧 Constraint satisfaction — planned
🚧 Travelling salesperson (TSP) — planned
🚧 Optimization — planned

④ What is happening mathematically?

Oracle: |x⟩ → (−1)^{f(x)}|x⟩. In this simulator f(x) is evaluated classically to build the oracle — on hardware it must be a reversible circuit.

⑤ What does the simulation show?

Candidates, the predicate, and the real Grover probability distribution.

⑥ What did we learn?

The hard part in practice is building an efficient oracle.

⑦ What can you experiment with?

Search the database for a phone number and compare the classical scan length.

📓 Record: my lab notebook

Write your observations. Notes are saved only in this browser.