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Weak Quantum Measurement: Trajectory vs. Collapse

Continuously monitor a qubit with an adjustable measurement strength. Watch a weak measurement build up a noisy, diffusing quantum trajectory on the Bloch sphere, versus a strong measurement collapsing it instantly — with a live information-vs-disturbance readout.

Quantum Physics3DAdvanced60 FPS

A strong, projective measurement of a qubit destroys superposition information instantly, forcing it into a definite outcome. A weak measurement instead couples only gently to the qubit, extracting a small noisy scrap of information per shot while leaving the state mostly intact. Repeating many weak measurements builds up a continuous, diffusing "quantum trajectory" toward one pole, with visible randomness along the way — something a single strong measurement can never show, since it only ever reveals the state at one destructive instant. Slide the measurement strength from weak to strong, run continuous monitoring, and compare against a single maxed-out strong measurement while watching the live information-gained-vs-disturbance-caused trade-off.

⚙ Under the hood

Continuously monitor a qubit prepared in superposition with an adjustable measurement-strength slider. Weak settings build a noisy, diffusing quantum trajectory on the Bloch sphere over many gentle measurements; a maxed-out strong measurement snaps the qubit to a pole in a single shot. A live readout compares information gained versus disturbance caused at the current strength.

quantum measurementweak measurementquantum trajectoryBloch spheremeasurement backactionqubitdecoherence

3D · Three.js / WebGL renderer · 60 FPS target · runs fully client-side, no install