Electric-field assisted optimal quantum transport of photo-excitations in polar heterostructures

Abstract

Transition-metal-oxide (TMO) heterostructures are promising candidates for building photon-harvesting devices which can exploit optimal quantum transport of charge excitations generated by light absorption.Here we address the explicit role of an electric field on the quantum transport properties of photo-excitations subject to dephasing in one-dimensional chains coupled to a continuum of states acting as a sink. We show that the average transfer time to the sink is optimized for suitable values of both the coupling strength to the sink and the electric field, thus fully exploiting the coherence-enhanced efficiency in the quantum transport regime achievable in few monolayers TMO heterostructures. The optimal coupling to the continuum remains approximately the same as that in absence of electric field and is characterizing the Superradiant Transition. On the other hand, the optimal electric field for which we provide estimates using an analytical expression is dependent on the initial state.

Protecting quantum coherences from static noise and disorder

“…with x = 0, 1, 3. This model, for instance, describes s-band electron transport in the presence of a strong electrical potential [50,51], and corresponds to an Anderson-type model [19] in the strong bias limit. Experimentally, it can be simulated using atom-optics simulators [52,53] or photonic waveguides [54][55][56].…”

“…with N the normalization constant and p Ga a Gaussian distribution with average (d + 1)/2 and variance √ d. This could, for instance, model a photoexcitation in a correlated thin-film transition metal-oxide heterostructure with a strong intrinsic electrical field [51].…”

Enhancement of impact ionization in Hubbard clusters by disorder and next-nearest-neighbor hopping

“…4. To quantify the weight shifts inside the upper Hubbard band (UHB), we separate it into the lower part of UHB (ω ∈ [0, 4]) and upper part of UHB (ω ∈ (4,8]). The division point of ω = 4, indicated in Fig.…”

“…Besides the prospects of impact ionization, transition metal oxides can be produced as hetrostructures with a potential gradient at a polar interface. This gradient or the corresponding field enables an electronhole separation and allows one to harvest the excess charge in form of a current 3,5,8,9 . Experimentally such transition metal oxide heterostructures have been demonstrated to act as solar cells, on the basis of the Mott insulators LaVO 3 10,11 and LaFeO 3 12 .…”

Eliminating radiative losses in long-range exciton transport

“…There are a variety of ways in which to introduce an energy gradient in nanoscale transport systems; e.g. chemical substitution in molecular systems [43], local strain engineering in atomically thin 1D and 2D materials [44][45][46], intrinsic electric fields within polar transitionmetal-oxide heterostructures [47,48] and external electric fields applied to coupled quantum wells [49][50][51]. For simple proof of concept experiments, fine-grained control over energetic gradients, as well as other system parameters, can also be achieved with superconducting circuits [52].…”