Quantum Game: Hands-on Activity

We will extend the classical game by introducing quantum superposition, creating a new version called Photonic Ship.

💾 Save your classical game code—you’ll need it for reference later.

🚀 You’ll build your Photonic Ship step by step through eight tasks.

🎮 Each task includes a playable version in your browser to test your progress.

Task 1 "Two screens"

• Double the height and draw a line in the middle.
• Now, we have two screens: The upper (lower) screen will represent state |0> (|1>).

Try Task 1 Game Version

💡 drawing a line with a specified color and starting & ending coordinates, from (x1,y1) to (x2,y2)
pygame.draw.line(screen, (R, G, B), (x1, y1), (x2, y2))

Task 2 "X gate"

• When pressing key "X", our ship should switch its screen (in the same position).
• When in the upper screen, the state of our ship is "|0>".
• When in the lower screen, the state of our ship is "|1>".
• Make sure that our ship cannot cross the middle line.

Try Task 2 Game Version

💡 Similar to importing "K_UP, K_DOWN, K_LEFT,...", we can import and use "K_x".

💡 Define a variable state, and update it whenever the state is changed.

💡 The following properties can be read and set:

 ship.rect.top 
 ship.rect.bottom

Task 3 "Display state"

• Display the state information on the top-right corner.

Try Task 3 Game Version

💡 Check how to display "Game Over!". This time we show the state info in each frame without any delay.

Task 4 "Hadamard"

• Apply Hadamard when pressing key "H".
• If in state |0> or |1>, the new state is |+> or |->, respectively.
• When entering |+> or |->, create a copy of ship and place it on the other screen.
• When in |+> or |->, our photonic ship is in superposition. We call it "quantum mode".
• When in quantum mode, make sure that the ships do not move.
• When in |+> or |-> and press "H", the new state is |0> or |1>, respectively. The mode is "classic".

Try Task 4 Game Version

💡 Define a variable twinship for the second ship. Check the code for creating the first ship.

💡 Check state before updating the ship position.

Task 5 "Quantum Mode"

• Make sure that the state info is displayed correctly on the top-right corner.
• When in state |+> or |->, the user can move only the enemies up and down.
• When pressing arrow keys "UP" or "DOWN", move every enemy accordingly.
• Enemies can cross the middle line, and when dropping from the top (resp., bottom), they appear again from the bottom (resp., top).
• Enemies should still move automatically to the left.

Try Task 5 Game Version

💡 Each enemy has enemy.rect.top for its vertical (y) position. Check the code for updating the enemy.

Task 6 "Measurement"

• When in a superposition (|+> or |->), what happens if one of the ships is hit by an enemy?
• We measure our system, and our ship collopses into the up (down) screen if |0> (|1>) is observed.
• Implement this measurement and update the game accordingly.
• After measurement, decide if the ship is hit (destroyed) or survived.
• Display an informative message about the measurement outcome and the status of ship.

Try Task 6 Game Version

💡 Collision check should be made for both ship and twinship.

💡 Randomly pick an integer from 1 to 100. The state 0 (1) is observed if this integer is even (odd).

💡 When collopsing, it is easier to remove twinship, but then ship should appear in the correct screen.

💡 Use state to determine the correct screen for ship.

💡 Collision check can be made once more for ship in the same frame after collapsing and placing the correct screen.

Task 7 "X and Z gates"

• When in a superposition (|+> or |->), make sure that pressing X does not change the state and so the game.
• When in (|0> or |1>), pressing Z does not change the state and so the game.
• But, when in a superposition (|+> or |->), pressing Z should switch |+> to |-> and vice versa.

Try Task 7 Game Version

Task 8 "Apply quantum gates randomly"

• Let the system applies the quantum gates (X, H, Z) randomly..
• For example, in each frame, pick a random integer between 0 and 300.
    • If it is 100 or 200, applies X.
    • If it is 50 or 250, applies Z.
    • If it is 150, applies H.
• Apply X only in the classic mode, and Apply Z only in the quantum mode.
• Play with the randomization parameters to make it more comfortable for yourself.

Try Task 8 Game Version