Charge detection using a WSe$_2$ van der Waals heterostructure

Abstract

Detecting single charging events in quantum devices is an important step towards realizing practical quantum circuits for quantum information processing. In this work, we demonstrate that van der Waals heterostructure devices with gated nano-constrictions in monolayer WSe 2 can be used as charge detectors for nearby quantum dots. These results open the possibility of implementing charge detection schemes based on 2D materials in complex quantum circuits.

Anomalous conductance quantization of a one-dimensional channel in monolayer WSe2

“…Electrical contacts [Cr (2 nm) / Pt (8 nm)] [41] were subsequently patterned on top of the hBN. To remove any contaminants on the surface of the hBN and the electrical contacts, the sample was thermally annealed in a vacuum furnace (10 −7 Torr) at 300 • C for 30 minutes and further cleaned mechanically using an atomic force microscope tip (AFM) in contact mode [7,21,50,51]. A second polymer stamp was used to subsequently pick-up an hBN flake (34 nm) then a monolayer WSe 2 flake.…”

“…Realization of quantum devices based on two-dimensional (2D) materials has attracted significant interest in recent years [1,2]; in particular, advances in fabrication techniques for devices based on transition metal dichalcogenides (TMDs) enabled the realisation of building blocks of quantum circuits such as gate-controlled quantum dots in monolayer and few layer MoS 2 [3][4][5] and WSe 2 [6,7] as well as one-dimensional (1D) channels based on split gate technology [8][9][10][11][12]. 1D channels are of great interest in quantum information science because they have been established as valuable tools for non-invasive readout of semiconducting charge and spin qubits in GaAs [13], SiGe [14], graphene [15][16][17][18], bilayer graphene [19,20] and WSe 2 [21]. In 1D channels, the Landauer-Buttiker formalism explains the quantized conductance in units of n e 2 /h, where n is the number of available transport channels, which depends on the degeneracies of the system; for example, 2-fold spin degeneracy for GaAs [22] and 4-fold spin and valley degeneracy for graphene [23].…”