Coherence Time
Figuratively, the time it takes for a quantum state to be subject to energy decay or dephasing, limits the operation fidelity on the qudits involved.
Quantum
Full Definition
Decoherence is a specific form of noise. The decoherence time \(t_Q\) is the time in which a quantum system loses its coherence1.
Examples
In nuclear spin systems there are two major sources of decoherence1:
- \(T_1\) spin-lattice/longitudinal relaxation
- \(T_2\) spin-spin/transverse relaxation
Both are associated with a different point in time \(t\). At \(T_1=t\), the net magnetization of a physical system is at 63% of its maximum value. At \(T_2=t\), the transverse magnetization of a physical system is at 37% of its initial value. For a detailed explanation see: T1 and T2
Figuratively speaking \(T_1\)-time, describes the probability of a qubit still being in \(\ket{1}\) after the time \(t\) and the \(T_2\)-time describes the probability of a qubit still being in \(\ket{+}\) after the time \(t\).