Effect of image charge on double quantum dot evolution

A charge-based qubit is subject to image forces originating in nearby metal gates. Displacement of charge in an oscillating qubit indispensably results in moving charges in metal. Therefore, Joule loss is one more source of qubit decoherence. We have estimated the quality of Rabi oscillations for a realistic double-quantum-dot as Q∼100Q∼100. This kind of decoherence cannot be suppressed by lowering temperature as it is evoked by surface roughness scattering of electrons which is almost insensitive to temperature. Possibilities to avoid such a decoherence are briefly discussed. The effect of energy dissipation and image charge potential on qubit dynamics is studied by means of a specific local-in-time non-Markovian master equation.

► We estimate the decoherence rate of charge qubits caused by Joule energy loss in nearby electrodes. ► For realistic gate-engineered qubits the quality of Rabi oscillations is around 100. ► Along with the decoherence, an image-force potential affects the qubit time evolution. ► The dynamics is studied by means of a specific local-in-time non-Markovian master equation.