014 Noise and Decoherence
SimulatorWatch a spinning coin lose its spin as time passes, then see why three copies and a vote help.
Simulator running in your browser. Real hardware: coming soon (planned provider: IBM Quantum).
What's happening?
A simulator for decoherence: slide the wait time and noise level to shrink the Bloch arrow and break the two-spin trick, then try a three coin vote to see why error correction exists. Simulator only.
You will learn: Decoherence, noise and the idea behind error correction.
What the model does
Part 1 spins a coin, waits, spins again and looks. Without noise the second spin cancels the first and gives Heads every time. Noise is modelled as random Shift the spin kicks during the wait, with a chance that grows with time. The arrow on the sphere shrinks by a factor that falls off exponentially with a time scale called T2, and the chance of Heads after the second spin is one half times one plus that factor. That is the exact result for this kind of noise.
What you are seeing
A long arrow is a clean mix. A short arrow is a coin that has partly forgotten how it was spun. The 100 run grid shows the effect: fewer than 100 Heads means noise broke the cancelling. This is why quantum computers work in cold, shielded setups and why long circuits are hard.
Honest notes
- Part 1 is a simplified model, pure dephasing. Real hardware also loses energy (T1) and has gate and readout errors, see Decoherence and Noise Explained.
- Part 2 is a classical toy. It protects Heads or Tails only. A quantum code cannot copy the state, see The No-Cloning Theorem Explained, and must correct both flips and sign errors. See Quantum Error Correction Explained and Quantum Error Correction in 2026 for what has been demonstrated.
- Many physical qubits are needed for one reliable logical qubit, which is why today's machines are not close to breaking wallet signatures, see Can a quantum computer break my wallet?.
Run on real hardware: coming soon. The planned provider is IBM Quantum. It is not connected yet. Every result on this page comes from a simulator running in your browser, not from a quantum computer.
How it works: the simulator keeps the exact quantum state of the qubits as a list of complex numbers, applies each gate to it, and draws random samples from the resulting probabilities. The random numbers are ordinary pseudo random numbers from your browser, and a real device would add noise. No QNT, wallet or account is needed.
Sources
- Nature (2024): Quantum error correction below the surface code threshold (Google Quantum AI)
- Wikipedia: Quantum decoherence
- Wikipedia: Quantum error correction
This is an educational simulator, not financial advice. QUANTUM (QNT) is an independent community token on Solana and does not perform quantum computation.