Observation of classical-quantum crossover of 1/f flux noise and its paramagnetic temperature dependence
Abstract
By analyzing the dissipative dynamics of a tunable gap flux qubit, we extract both sides of its
two-sided environmental flux noise spectral density over a range of frequencies around 2kBT /h ≈
1 GHz, allowing for the observation of a classical-quantum crossover. Below the crossover point,
the symmetric noise component follows a 1/f power law that matches the magnitude of the 1/f
noise near 1 Hz. The antisymmetric component displays a 1/T dependence below 100 mK, providing
dynamical evidence for a paramagnetic environment. Extrapolating the two-sided spectrum predicts
the linewidth and reorganization energy of incoherent resonant tunneling between flux qubit wells.
two-sided environmental flux noise spectral density over a range of frequencies around 2kBT /h ≈
1 GHz, allowing for the observation of a classical-quantum crossover. Below the crossover point,
the symmetric noise component follows a 1/f power law that matches the magnitude of the 1/f
noise near 1 Hz. The antisymmetric component displays a 1/T dependence below 100 mK, providing
dynamical evidence for a paramagnetic environment. Extrapolating the two-sided spectrum predicts
the linewidth and reorganization energy of incoherent resonant tunneling between flux qubit wells.
Research Areas
