arXiv subjects

Maopeng Wu

Publications and source records attributed to Maopeng Wu.

4 recordsLinked to original sources

arXiv2026

Topological Metamaterial for Magnetic Resonance Imaging

Magnetic Resonance Imaging (MRI) is crucial in global healthcare, but the traditional receive coils, as a core component of MRI, SNR enhancement is limited due to the optimization of channel number and magnetic field strength faces high cost and complexity challenges. Here, we demonstrate the use of a topological material to enhance MRI signal reception. Designed with a stack of weak couplings, this material forms quasi-two-dimensional dual topological boundary states. High properties are achieved through low-loss signal transmission via these topological states, as well as only enhanced local magnetic fields and increased number of channels. Initial tests demonstrate superior performance and accessibility compared to commercial coils, suggesting significant potential. This concept introduces a transformative paradigm for all MRI coil designs.

physics.app-ph↗

arXiv2022

Evidencing non-Bloch dynamics in temporal topolectrical circuits

One of the core concepts from the non-Hermitian skin effect is the extended complex wavevectors (CW) in the generalized Brillouin zone (GBZ), while the origin of CW remains elusive, and further experimental demonstration of GBZ is still lacking. We show that the bulk states of an open quantum system dynamically governed by the Lindblad master equation exhibit non-Bloch evolution which results in CW. Experimentally, we present temporal topolectrical circuits to serve as simulators for the dynamics of an open system. By reconstructing the correspondence between the bulk states of an open system and circuit voltage modes through gauge scale potentials in the circuit, the non-Bloch evolution is demonstrated. Facilitated by the simulators and proper approach to characterize the non-Bloch band proposed here, the GBZ is confirmed. Our work may advance the investigation of the dissipative topological modes and provide a versatile platform for exploring the unique evolution and topology for both closed and open systems.

cond-mat.mtrl-sci↗

arXiv2022

Observing the nodal-line conversion determined by the relative homotopy

Directly identifying the non-Abelian nodal-line semimetals (NASM) is quite challenging because nodal-line semimetals typically do not possess topologically protected boundary modes. Here, by reconstructing the correspondence between the bulk states of Hermitian systems and circuit voltage modes through gauge scale potential, the temporal topolectrical circuits (TTC) for evidencing NASM are proposed. Following the logical progress of discovering NASM, we start by demonstrating the relative homotopy group of two-band models using TTC, which can faithfully determine the conversion rules between the nodes in and out of the non-local-symmetry invariant subspace. Next, we show that those rules dramatically change with the consideration of the additional band, historically leading to the arising of the NASM. Also, we demonstrate the unique non-Abelian constrained nodal configuration -- earring nodal lines. Our results established NASM for further investigating topological line degeneracies, and proposed TTC will be a versatile platform for exploring nodal-line semimetals.

cond-mat.mes-hall↗

arXiv2020

Direct observation of energy band attraction effect in non-Hermitian systems

The energy band attraction (EBA) caused by the non-orthogonal eigenvectors is a unique phenomenon in the non-Hermitian (NH) system. However, restricted by the required tight-binding approximation and meticulously engineered complex potentials, such effect has not been experimentally demonstrated. Here, an experimentally verifiable model is proposed based on the photonic counterpart of the all-dielectric Mie-resonator lattice in a parallel-plate transmission line. Through theoretical derivation, we directly connect the transmission spectra with eigenvalues and eigenvectors of the NH Hamiltonians. By precisely tuning the resonance loss of the Mie-resonators, the evolution of the EBA effect in two-level NH systems, from gapped bands, gapless bands to flat bands, is directly observed for the first time. Furthermore, such effect can be extended to a graphene-like two-dimensional NH system. Our works show a metamaterial approach towards NH topological photonics and offer a deeper understanding of band theory in open systems.

cond-mat.mes-hall↗