Fig. 4: 2P:1P ∥ [100] qubit fidelity in the presence of charge noise.
From: Optimisation of electron spin qubits in electrically driven multi-donor quantum dots
![Fig. 4: 2P:1P ∥ [100] qubit fidelity in the presence of charge noise.](http://media.springernature.com/full/springer-static/image/art%3A10.1038%2Fs41534-022-00646-9/MediaObjects/41534_2022_646_Fig4_HTML.png?as=webp)
a A schematic of a charge defect q placed at an angle ϕ w.r.t. to qubit axis and a distance R nm away from the center of the qubit i.e. the midpoint between 2P and 1P dots. The vertical separation of the defect from the qubit plane is h. The multi-donor quantum dot qubit oriented along [100]. For the calculations presented in panel b-d,f, the 2P − 1P distance is 14.4 nm; the 2P − 1P tunneling energy is t = 1 meV. b variation of fluctuations in the tunneling energy (blue) Δt and fluctuations in detuning (orange) Δv as a function of in-plane (h = 0) angular orientation ϕ of the charge defect, R = 40 nm. The oscillation of Δt determines in which directions charge noise should be avoided; for all orientations, Δv is nearly constant, and comparable to the highest Δt. c variation of Δt (blue) and Δv (orange) as a function of charge defect in-plane distance R from the center of the qubit, ϕ = 40o. d variation of Δt (blue) and Δv (orange) as a function of charge defect height h from the qubit plane; R = 40 nm, ϕ = 40o. e dephasing time due to random telegraph noise (RTN), \(({T}_{2,RTN}^{* })\) as a function of detuning (δ) for random telegraph noise, with an external magnetic field of 1T; R = 30 nm, ϕ = 40o, h = 0. The top label shows the detuning field range to be ± 2 meV around the anti-crossing. f The dephasing time (\({T}_{2,1/f}^{* }\)) due to 1/f noise, as a function of detuning (δ). We consider the defect potential up to first order in detuning fluctuation, which formally limits \({T}_{2,1/f}^{* }\) to 5 s at the anti-crossing.
