arXiv subjects

Lucca Valerius

Publications and source records attributed to Lucca Valerius.

3 recordsLinked to original sources

arXiv2025

Dinosaur Photonic Crystal Cavity Interfaces for Color Center Coupling to Triangular Nanostructures

Waveguide-coupled photonic crystal cavities with a triangular cross section fabricated by angled etching are suitable to interface embedded color centers with flying photonic qubits in quantum information applications. Moreover, their fabrication requires fewer processing steps compared to nanostructures produced by quasi-isotropic undercutting. As an alternative to established hole-based photonic crystal cavities, we introduce corrugated triangular 'Dinosaur' photonic crystal cavities, and develop a tapered, quasi loss-free cavity-waveguide interface to adiabatically interconvert Bloch and waveguide modes. We optimize the cavity-waveguide interface to minimize photon losses and demonstrate that its adjustment allows precise tuning of the light-matter interaction.

physics.optics↗

arXiv2025

Radio-frequency charge detection on graphene electron-hole double quantum dots

High-fidelity detection of charge transitions in quantum dots (QDs) is a key ingredient in solid state quantum computation. We demonstrate high-bandwidth radio-frequency charge detection in bilayer graphene quantum dots (QDs) using a capacitively coupled quantum point contact (QPC). The device design suppresses screening effects and enables sensitive QPC-based charge readout. The QPC is arranged to maximize the readout contrast between two neighboring, coupled electron and hole QDs. We apply the readout scheme to a single-particle electron-hole double QD and demonstrate time-resolved detection of charge states as well as magnetic field dependent tunneling rates. This promises a high-fidelity readout scheme for individual spin and valley states, which is important for the operation of spin, valley or spin-valley qubits in bilayer graphene.

cond-mat.mes-hall↗

arXiv2023

Impact of competing energy scales on the shell-filling sequence in elliptic bilayer graphene quantum dots

We report on a detailed investigation of the shell-filling sequence in electrostatically defined elliptic bilayer graphene quantum dots (QDs) in the regime of low charge carrier occupation, $N \leq 12$, by means of magnetotransport spectroscopy and numerical calculations. We show the necessity of including both short-range electron-electron interaction and wavefunction-dependent valley g-factors for understanding the overall fourfold shell-filling sequence. These factors lead to an additional energy splitting at half-filling of each orbital state and different energy shifts in out-of-plane magnetic fields. Analysis of 31 different BLG QDs reveals that both valley g-factor and electron-electron interaction induced energy splitting increase with decreasing QD size, validating theory. However, we find that the electrostatic charging energy of such gate-defined QDs does not correlate consistently with their size, indicating complex electrostatics. These findings offer significant insights for future BLG QD devices and circuit designs.

cond-mat.mes-hall↗