a study instrument · ephemeral qubits · 2-qubit sandbox
Ephemeral Qubit Lab
a model — faithful mirror, no quantum advantage, learns only the mechanics you run
This is a real density-matrix simulator of two qubits, running the actual linear algebra — superposition, gates, entanglement, measurement, and decoherence. It's a perfect place to study the mechanics, because you can see every amplitude and rewind at will. But it runs on a classical computer: it gives you the picture of qubits and none of the speedup, and it can only ever do the physics you code in. Use it to understand a qubit — never to get one.
Controls
Target qubit (for 1-qubit gates & noise)
Single-qubit gates
Two-qubit gates
control:
Presets
Measurement (collapses the state)
Decoherence — strength 0.30
State
Qubit 0
|r| = 1.00
Qubit 1
|r| = 1.00
Measurement probabilities
State vector (when pure)
|00⟩
Readouts
Circuit log
What you're seeing — honestly. The Bloch vectors shrink for two different reasons: entanglement (the qubit's state lives in the pair, not in itself — check that global purity stays 1.00) or decoherence (noise has made the global state mixed — purity drops below 1.00). That distinction is real and worth watching. · This sandbox is a faithful mirror and a terrible shortcut: it reproduces qubit mechanics exactly, but being classical it offers no quantum advantage, and it can only show physics you've encoded — it will never surprise you with new physics the way real hardware can. Study a known mechanism here; discover an unknown one in a lab.