Non-local triple quantum dot thermometer based on Coulomb-coupled systems

Abstract

Recent proposals towards non-local thermoelectric voltage-based thermometry, in the conventional dual quantum dot set-up, demand an asymmetric step-like system-to-reservoir coupling around the ground states for optimal operation (Physica E, 114, 113635, 2019). In addition to such demand for unrealistic coupling, the sensitivity in such a strategy also depends on the average measurement terminal temperature, which may result in erroneous temperature assessment. In this paper, I propose non-local current based thermometry in the dual dot set-up as a practical alternative and demonstrate that in the regime of high bias, the sensitivity remains robust against fluctuations of the measurement terminal temperature. Proceeding further, I propose a non-local triple quantum dot thermometer, that provides an enhanced sensitivity while bypassing the demand for unrealistic step-like system-to-reservoir coupling and being robust against fabrication induced variability in Coulomb coupling. In addition, I show that the heat extracted from (to) the target reservoir, in the triple dot design, can also be suppressed drastically by appropriate fabrication strategy, to prevent thermometry induced drift in reservoir temperature. The proposed triple dot setup thus offers a multitude of benefits and could potentially pave the path towards the practical realization and deployment of high-performance non-local "sub-Kelvin range" thermometers.