Figure 1: Qubit in a noisy environment.
From: Measurement of geometric dephasing using a superconducting qubit
Bloch vectors (green arrows) describing the qubit state after evolving adiabatically in an precessing noisy magnetic field. When the qubit state evolves adiabatically, its Hilbert space can be identified with the parameter space of the Hamiltonian, that is, the three-dimensional effective magnetic field. The magnetic field (white line) follows a closed loop n times. In a, the number of loops is n=+1, in b it is n=−1. Owing to geometric dephasing, the Bloch vectors are fanned out more in a than in b.
