QUANTUM GAMES · FACILITATOR GUIDE

Ghost Guard

Learning goal: Parity checks can locate one bit flip without revealing the encoded secret.

Prepare

Groups of three; about 45 minutes. Prepare the mat, secret and action cards, tracker, six coins, two chip colors, a screen and a ten-sided die; or use the offline game.

Lead the game

Assign Keeper, Guardian and Gremlin. Set up both rows in secret. For seven nights, reveal Gremlin’s action privately to Keeper, then Guardian’s action. On a check, report only the two neighboring match results; correct using the check table. Give the final free check and compare with the secret card.

Help players

A flip affects the named coin in both rows. Do not disclose coin values. Two flips between checks can mislead the one-error correction rule.

Level 2 diagnosis

Present Level 2 as an unscored challenge. The Sign error cannot be repaired with the available Check and Flip cards. Use the short Sign + Check example; ask learners to compare the changed chip colors with the unchanged parity answers, then explain the need for phase-sensitive checks and corrections. Keep this separate from the Level 1 duel score.

Discuss

Ask: What did the check reveal? What could it not tell you?

Science note

This model corrects one bit flip; it does not correct all errors. A direct peek destroys the modeled secret.