Abstract
We discuss the transport properties of thermal electrons in double quantum dots that are coupled with Majorana bound states (MBSs) corresponding to two model systems with T-type structure and series connection structure. It has been found that the thermoelectric figure of merit ZT in these model systems is suppressed when we consider the effects of the Majorana bound states. Here, ZT=GS2Tκ, where G is the electric conductance, S is the thermopower, T is the temperature and κ is the thermal conductance. The sign of the thermopower S changes from negative to positive when the energy levels of the quantum dots are less than μ while the sign of the thermopower S changes from positive to negative when the energy levels of the quantum dots are above μ in the model system of T-type structure, where μ is the chemical potential. As a result, the figure of merit ZT first decreases and then increases as the temperature kBT increases. This behavior is different from what is seen in the general quantum dot structure without MBSs. It is interesting to show that in the series connection structure, the thermopower S and ZT are robustness and do not vary with changes in εM when |εd|<λ, even if κ changes with εM.
Highlights
Searches for Majorana fermions and the means of controlling Majorana bound states (MBSs) in solid-state devices have attracted a lot of attention due to their fundamental interest and to potential applications in quantum computation.[1,2,3,4,5,6,7] In distinction from conventional Dirac fermions, Majorana fermions are their own antiparticles and the quasiparticle operators satisfy η = η†
125032-4 Zheng, Song, and Li and the right lead; HMBS = iεM η1η2 + λ1 d1†η1 + η1†d1 + λ2 d2†η2 + η2†d2 describes the coupling between the two Majorana bound states and the coupling between the Majorana bound states and the quantum dots, where η1 and η2 are the Majorana fermion zero modes at the two ends of the quantum wire, εM is the strength of the coupling between the two Majorana bound states, λ1 and λ2 are the couplings between the Majorana fermion zero modes and the quantum dots
We first calculate the thermoelectric properties of the T-type structure without Majorana bound states, which is shown in the inset of Fig. 2(a)
Summary
Searches for Majorana fermions and the means of controlling Majorana bound states (MBSs) in solid-state devices have attracted a lot of attention due to their fundamental interest and to potential applications in quantum computation.[1,2,3,4,5,6,7] In distinction from conventional Dirac fermions, Majorana fermions are their own antiparticles and the quasiparticle operators satisfy η = η† They show non-Abelian statistics[8] which leads to numerous extraordinary phenomena that we are interested in exploring.[9].
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