Double nanowires for hybrid quantum devices

Abstract

Parallel one-dimensional semiconductor channels connected by a superconducting strip constitute the core platform in several recent quantum device proposals that rely e.g. on Andreev processes or topological effects. In order to realize these proposals, the actual material systems must have high crystalline purity and the coupling between the different elements should be controllable in terms of their interfaces and geometry.We present a strategy for synthesizing double InAs nanowires by the vapor-liquid-solid mechanism using III-V molecular beam epitaxy. A superconducting layer is deposited onto nanowires without breaking vacuum, ensuring pristine interfaces between the superconductor and the two semiconductor nanowires. The method allows for a high

Scalable platform for nanocrystal-based quantum electronics

“…Details can be found in the Methods section and recently published work. [27] The hexagonal shapes of the single NCs appear somewhat irregular, which is an artifact from the close spacing of the single nanowires grown under unoptimized conditions. As inter-nanowire spacings decrease local growth parameters change due to temperature fluctuations and variations in shared collection areas.…”

“…Recently, controlled growth of merged superstructures of nanowires has been demonstrated, [27] as well as semiconductor/superconductor nanowire heterostructures composed of III/V materials and Sn, Pb, and Al, known as hybrid devices. [47][48][49][50][51][52][53] These emerging materials are in high demand as they are proposed to serve as a foundation for emerging quantum information technologies.…”

“…By use of standard EBL processes, catalyst particles can be placed on the growth substrate in predetermined patterns, and when VLS growth is initiated nanowires are formed at the locations of the catalyst particles. [27] Given the conditions under standard VLS growth (see Methods for details) the nanowires grow predominantly in the vertical direction with respect to the InAs (111)B substrate, and only minimally in their radial directions {1 100}. Controlling the design of the catalyst particle placement, this can result in extremely closely spaced single nanowires, as illustrated in the cross-section view in Figure 4a (i).…”

“…An exhaustive description can be found in recently published work. [27] Microtomy. InAs growth substrate are cleaved into smaller pieces containing the as-grown free standing nanowire arrays.…”

Violation of the Wiedemann-Franz law in the Topological Kondo model

“…The devices in [73] potentially provide a candidate for observing the (TK) fixed point. For instance, assuming an effective coupling in (3) of J K ≈ 0.005meV , a density of states ρ 0 ∼ 20meV −1 and a bandwidth D 0 ∼ E c ∼ 1meV , one obtains a Kondo temperature T K ∼ 22mK.…”