Decoherence time is the time scale over which a quantum system maintains its coherent quantum state. It represents how long a system can reliably exhibit quantum properties like superposition and entanglement before interacting with its environment causes it to behave classically.
Key Points:
- Loss of Coherence: Quantum states are fragile. Environmental noise, thermal vibrations, and electromagnetic interference can cause the system to lose its quantum correlations.
- Critical for Quantum Computing: Decoherence time sets an upper bound on how long quantum operations can be performed without errors.
- Material and Design Dependent: Different quantum systems (e.g., trapped ions, superconducting qubits, NV centers) have different decoherence times depending on their isolation and engineering.
To build practical quantum devices, systems must perform all required operations within the decoherence time, or use error correction techniques to extend their effective coherence.