In quantum computing, [[Coherence Time|coherence time]] refers to the duration over which a qubit maintains its quantum state (superposition and entanglement) before [[Decoherence|decoherence]] disrupts it due to interactions with the environment. It is a critical parameter determining the feasibility of quantum computations, as longer coherence times allow for more operations to be performed without significant errors. There are two main types: **$T_1$ (relaxation time)**, which measures how long a qubit retains its energy state, and **$T_2$ (dephasing time)**, which quantifies how long phase coherence between quantum states is preserved. Improving coherence time through [[Quantum Error Correction|error correction]], better isolation, and advanced materials is essential for building [[DiVincenzo Criteria|scalable]] and reliable quantum computers. >[!read]- Further Reading >[!ref]- References