Orbital effects of a strong in-plane magnetic field on a gate-defined quantum dot

Abstract

We theoretically investigate the orbital effects of an in-plane magnetic field on the spectrum of a quantum dot embedded in a two-dimensional electron gas (2DEG). We derive an effective twodimensional Hamiltonian where these effects enter in proportion to the flux penetrating the 2DEG. We quantify the latter in detail for harmonic, triangular, and square potential of the heterostructure. We show how the orbital effects allow one to extract a wealth of information, for example, on the heterostructure interface, the quantum dot size and orientation, and the spin-orbit fields. We illustrate the formalism by extracting this information from recent measured data [L. C. Camenzind, et al., arXiv:1804.00162; Nat. Commun. 9, 3454 (2018)]. arXiv:1804.00128v2 [cond-mat.mes-hall]

3D Map of a Quantum Dot’s Potential

“…III in the Supplemental Material [17]). For an elongated (quasi-1D) dot, the states would oscillate in phase [16]. Beyond confirming that our dot is indeed close to a symmetric one, we can specify its orientation in detail.…”

“…The theoretical principles of the method are explained in Ref. [16]. Here, we demonstrate it experimentally.…”

“…where e > 0 is the elementary charge and λ z is the effective width of the wave function along the growth direction. We analyze the connection between a nominal width and the effective width of a 2DEG for several confinement profiles, namely, triangular, harmonic, and a square potential well [16]. Also, we note that flux threading was previously studied in open dots [36][37][38].…”

“…In Ref. [16], we show that the leading order effect can be expressed as a correction to Eq. (1) of the following form [35]:…”

Machine learning enables completely automatic tuning of a quantum device faster than human experts

“…A bias voltage V bias is applied to ohmic contacts to drive a current (I) through the device. The device schematic, designed for precise control of the confinement potential [15][16][17] , is shown in Fig. 1a.…”