Variability mitigation in epitaxial-heterostructure-based spin qubit devices via gate layout optimization
arxiv(2024)
摘要
The scalability of spin qubit devices is conditioned by qubit-to-qubit
variability. Disorder in the host materials indeed affects the wave functions
of the confined carriers, which leads to variations in their charge and spin
properties. Charge disorder in the amorphous oxides is particularly detrimental
owing to its long-range influence. Here we analyze the effects of charge traps
at the semiconductor/oxide interface, which are generally believed to play a
dominant role in variability. We consider multiple random distributions of
these interface traps and numerically calculate their impact on the chemical
potentials, detuning and tunnel coupling of two adjacent quantum dots in SiGe
heterostructure. Our results highlight the beneficial screening effect of the
metal gates. The surface of the heterostructure shall, therefore, be covered as
much as possible by the gates in order to limit variability. We propose an
alternative layout with tip-shaped gates that maximizes the coverage of the
semiconductor/oxide interface and outperforms the usual planar layout in some
regimes. This highlights the importance of design in the management of
device-to-device variability.
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