11 research outputs found
Driven coherent oscillations of a single electron spin in a quantum dot
The ability to control the quantum state of a single electron spin in a
quantum dot is at the heart of recent developments towards a scalable
spin-based quantum computer. In combination with the recently demonstrated
exchange gate between two neighbouring spins, driven coherent single spin
rotations would permit universal quantum operations. Here, we report the
experimental realization of single electron spin rotations in a double quantum
dot. First, we apply a continuous-wave oscillating magnetic field, generated
on-chip, and observe electron spin resonance in spin-dependent transport
measurements through the two dots. Next, we coherently control the quantum
state of the electron spin by applying short bursts of the oscillating magnetic
field and observe about eight oscillations of the spin state (so-called Rabi
oscillations) during a microsecond burst. These results demonstrate the
feasibility of operating single-electron spins in a quantum dot as quantum
bits.Comment: Total 25 pages. 11 pages main text, 5 figures, 9 pages supplementary
materia
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Hydrogen evolution activity of individual mono-, bi-, and few-layer MoS2 towards photocatalysis
We investigate the hydrogen evolution activity in the dark and under illumination above the band gap of individual mono-, bi- and few-layer (bulk) MoS2 flakes. We demonstrate that the electrocatalytic activity of 2H-MoS2 immersed in 1 M H2SO4 increases with decreasing number of layers. For monolayers, we observe the highest exchange current density, which is one magnitude larger than in the bulk case. The onset potential scales with the number of layers, which is consistent with a previous report, suggesting that hopping transport across inter-layer barriers within the MoS2 flakes is responsible for this scaling. A specially designed micro-sized catalytic cell enables us to investigate individual MoS2 flakes with well-known geometry and edge-to-surface ratio. Taking these geometric parameters into account, we tentatively attribute the catalytic activity mainly to sulfur vacancies in the basal planes acting as active sites. The associated turn over frequencies (TOF) for mono- and bi-layer MoS2 yield values higher than 103 s−1 at an overpotential of −0.2 V vs. RHE. In view of light driven hydrogen evolution as a means of solar energy conversion, we investigate the photocatalytic activity of few-layer MoS2 under white light illumination
Light–Matter Interaction in Quantum Confined 2D Polar Metals
10.1002/adfm.202005977Advanced Functional Materials3142005977-200597