Interacting Two-Level Systems as a Source of 1/f Noise in Semiconductor Quantum Dot Qubits

Charge noise in quantum dots has been attributed one or two fluctuators coupled to each quantum dot. To explain why the observed charge noise has a 1/f spectrum rather than the expected Lorentzian, we propose a model in which a quantum dots are coupled to one or two fluctuators that have electric dipole moments. These fluctuators are in turn coupled elastically to a bath of fluctuating elastic dipoles that cause changes in the energy of the electric dipole fluctuators, resulting in 1/f charge noise. We simulate this model with Ising spin glasses in both 2D and 3D. We determine the magnetization noise spectrum of a few chosen Ising spins, each of which we imagine to be coupled to a quantum dot. The noise exponents are computed from the noise power spectra observed at three types of spins where the magnitude of the local field is small (|hlocal ≈ 0|), medium (|hlocal ≈ 2|), and large (|hlocal ≈ 4|). The ranges of the noise exponents are consistent with those found experimentally. The noise exponents depend on the local field and tend to increase with the magnitude of the local field.