arXiv subjects

David J. Apigo

Publications and source records attributed to David J. Apigo.

4 recordsLinked to original sources

arXiv2023

Isolating a Single Microtubule in Nanofluidic Device

Biological systems have been theoretically predicted to support phononic topological wave-modes, similar to the ones existing in meta-materials. The existing methods to measure these modes, however cannot be applied to biological systems; new techniques have to be developed to accommodate phononic measurements in life science. Motivated by this perspective, we report a nanofluidic device for studying one microtubule at a time. Microchannels etched into fused-silica using reactive ion etching were interfaced with nanochannels written and etched by electron beam lithography and reactive ion etching, and sealed with a PDMS-coated glass coverslip. The microchannels are 1 micron deep and 100 micron wide, and the nanochannels are 150 nm deep and 750 nm wide, they are tested to be effective for isolating microtubules. The methods presented here are for an adaptable nanofluidic platform for phonon measurements in biopolymers made of proteins or DNA.

physics.bio-ph↗

arXiv2022

Observation of Phase Controllable Majorana-like Bound States in Metamaterial-based Kitaev Chain Analogues

We experimentally demonstrate that Majorana-like bound states (MLBSs) can occur in quasi-one-dimensional metamaterials, analogous to Majorana zero modes (MZM) in the Kitaev chain. In a mechanical spinner ladder system, we observe a topological phase transition and spectral-gap-protected edge MLBSs. We characterize the decaying and oscillatory nature of these MLBS pairs and their phase-dependent hybridization. It is shown that the hybridization can be tuned to yield the analogue of parity switching in MZMs, a key element of topological qubits. We find strong agreements with theory.

cond-mat.mtrl-sci↗

arXiv2019

Observation of topological edge modes in a quasi-periodic acoustic waveguide

Topological boundary and interface modes are generated in an acoustic waveguide by simple quasi-periodic patternings of the walls. The procedure opens many topological gaps in the resonant spectrum and qualitative as well as quantitative assessments of their topological character are supplied. In particular, computations of the bulk invariant for the continuum wave equation are performed. The experimental measurements reproduce the theoretical predictions with high fidelity. In particular, acoustic modes with high Q-factors localized in the middle of a breathable waveguide are engineered by a simple patterning of the walls.

cond-mat.mes-hall↗

arXiv2018

Theory and Experimental Investigation of the Quantum Valley Hall Effect

The quantum valley Hall effect (QVHE) has been observed in a variety of experimental setups, both quantum and classical. While extremely promising for applications, one should be reminded that QVHE is not an exact topological phenomenon and that, so far, it has been fully understood only qualitatively in certain extreme limits. Here we present a technique to relate QVHE systems with exact quantum spin-Hall insulators that accept real-space representations, without taking any extreme limit. Since the bulk-boundary correspondence is well understood for the latter, we are able to formulate precise quantitative statements about the QVHE regime and its robustness against disorder. We further investigate the effect using a novel experimental platform based on magnetically coupled spinners. Visual renderings, quantitative data and various tests of the domain-wall modes are supplied, hence giving an unprecedented insight into the effect.

cond-mat.mes-hall↗