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Three Quantum Moves
Spin a quantum coin, make two waves cancel, then link a pair. Superposition, interference and entanglement as three quick games.
Move 1 of 3 · Superposition
A qubit is a spinning coin
A normal bit is a coin lying flat: heads (0) or tails (1). A qubit can spin. While it spins it is both. Catch it and it picks one.
Try this
- Spin the coin, then catch it.
- Catch it again without spinning. Same face?
- Spin and catch 100. About half each?
Real names: spinning = superposition. Catching = measurement. A real spinning coin is only hard to read. A qubit truly has no answer yet, and Move 2 shows the difference.
Move 2 of 3 · Interference
Two waves can cancel out
A qubit's chances move like waves. Waves in step add up. Waves out of step cancel, the way noise-cancelling headphones kill a sound. Here a coin is spun twice, then caught.
Waves reaching heads
Together
Waves reaching tails
Together
A normal coin has no waves, so nothing can cancel.
Try this
- Run 100. Does tails ever show up?
- Flip the second wave and run 100. What cancels now?
- Switch to a normal coin and run 100.
Real names: waves adding up or cancelling = interference. A quantum computer uses it to cancel wrong answers and grow the right one.
Move 3 of 3 · Entanglement
Two coins that always agree
Take two spinning coins, A and B. Link them, move them far apart, and catch both. Each one is random. Together they always match.
Try this
- Separate coins: catch 100 pairs. How often do they match?
- Link them and catch one pair.
- Still linked: catch 100 pairs. Any that differ?
No message passes between them. Each coin alone is a plain coin flip, so this cannot send a signal faster than light.
Real names: linked = entangled. This pair is a Bell state. Two coins fixed in advance could fake a match like this one. Ruling that out takes a harder experiment called a Bell test, and real entangled pairs pass it.
Quick check · 3 questions · under a minute
Did it land?
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Watch the one-minute versions
Behind the sim
What I simplified
Every result is drawn at random in your browser from the standard rules for one and two qubits, so your tallies wobble around the odds, as real measurements do. The spinning coin is a picture, not the physics: a real coin always has a hidden side, and a qubit does not. Two coins fixed in advance could fake the match shown in Move 3. Ruling that out takes a Bell test, which entangled pairs pass.
Sources (4)
- Basics of quantum information (course)quantum.cloud.ibm.com
- HGate, the Hadamard gate (Qiskit API reference)quantum.cloud.ibm.com
- Press release: The Nobel Prize in Physics 2022nobelprize.org
- Loophole-free Bell inequality violation using electron spins separated by 1.3 kilometresnature.com
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