arXiv subjects

Guo-Fu Xu

Publications and source records attributed to Guo-Fu Xu.

6 recordsLinked to original sources

arXiv2026

Non-Hermitian sensing via end-to-end Green's functions

Sensing hinges on two key attributes: high sensitivity and resilience to noise. Here, we present a scheme that unites these features within a single framework. By harnessing the exponential amplification of end-to-end Green's functions-a direct signature of the non-Hermitian skin effect-our scheme achieves an exponential sensitivity scaling of exp({\alpha}L) with {\alpha} a model-specific constant and L the system size. Notably, this enhanced sensitivity is protected by spectral winding numbers and endures under disorder when the non-Hermitian topological phase remains intact. We also explore its feasibility in synthetic non-Hermitian platforms, providing a pathway toward highly sensitive and noise-tolerant sensing.

quant-ph↗

arXiv2025

Size-dependent critical localization

Studying critical states in quasiperiodic systems is of great importance in localization physics. Previously identified critical states share a common characteristic: they exhibit persistent critical features in the thermodynamic limit. In this Letter, we predict an exotic type of critical state, termed size-dependent critical states, which exhibit a fundamentally distinct behavior. Specifically, they display critical localization signatures only at finite sizes, but transition to Anderson localization in the thermodynamic limit. We establish that the physical origin of size-dependent critical states lies in the synergistic interplay between local non-reciprocal domain wall and NHSE. By revealing a critical phase that challenges the established paradigm of critical localization, our work opens new avenues for exploring localization phenomena in quasiperiodic systems.

cond-mat.dis-nn↗

arXiv2025

Intrinsic-perturbation induced anomalous higher-order boundary states in non-Hermitian systems

The behavior of higher-order boundary states in non-Hermitian systems is elusive and thereby finding the mechanism behind these states is both essential and significant. Here, we uncover a novel mechanism that induces anomalous higher-order boundary states. The mechanism originates from the sensitivity of the non-normal boundary Hamiltonian to intrinsic perturbations, where intrinsic perturbations here refer to the influence of the bulk on the topological boundaries. Based on the mechanism, we reveal a new kind of phase transition, i.e., the transition between hybrid skin-topological states and scale-free topological boundary states. We also find that scale-free topological boundary states exhibit size-dependent spectra, influencing the existence of higher-order topological boundary states. Unlike conventional hybrid skin-topological states or higher-order non-Hermitian skin effect, the above two kinds of anomalous higher-order boundary states exhibit size-dependent characteristics. Our work opens a new horizon for the control of higher-order boundary states and topological properties of non-Hermitian systems.

cond-mat.mes-hall↗

arXiv2025

Anisotropic-scaling localization in higher-dimensional non-Hermitian systems

Spatial localization of quantum states is one of the focal points in condensed matter physics and quantum simulations, as it signatures profound physics such as nontrivial band topology and non-reciprocal non-Hermiticity. Yet, in higher dimensions, characterizing state localization becomes elusive due to the sophisticated interplay between different localization mechanisms and spacial geometries. In this work, we unveil an exotic type of localization phenomenon in higher-dimensional non-Hermitian systems, termed anisotropic-scaling localization (ASL), where localization lengths follow distinct size-dependent scaling rules in an anisotropic manner. Assisted with both analytical solution and numerical simulation, we find that ASL can emerge from two different mechanisms of effective bulk couplings or one-dimensional junction between different 1D edges, depending on how non-reciprocity is introduced to the system. The competition between ASL states and edge non-Hermitian skin states are further identified by their complex and real eigenenergies, respectively. Our results resolve the subtle co-existence of loop-like spectrum and skin-like localization of boundary states in contemporary literature, and provide a framework to classify the intricate higher-order non- Hermitian localization regarding their localization profiles.

cond-mat.mes-hall↗

arXiv2023

Average value estimation in nonadiabatic holonomic quantum computation

Nonadiabatic holonomic quantum computation has been attracting continuous attention since it was proposed. Until now, various schemes of nonadiabatic holonomic quantum computation have been developed and many of them have been experimentally demonstrated. It is known that at the end of a computation, one usually needs to estimate the average value of an observable. However, computation errors severely disturb the final state of a computation, causing erroneous average value estimation. Thus for nonadiabatic holonomic quantum computation, an important topic is to investigate how to better give the average value of an observable under the condition of computation errors. While the above topic is important, the previous works in the field of nonadiabatic holonomic quantum computation pay woefully inadequate attention to it. In this paper, we show that rescaling the measurement results can better give the average value of an observable in nonadiabatic holonomic quantum computation when computation errors are considered. Particularly, we show that by rescaling the measurement results, $56.25\%$ of the computation errors can be reduced when using depolarizing noise model, a widely adopted noise model in quantum computation community, to analyse the benefit of our method.

quant-ph↗

arXiv2020

Robust-fidelity hyperparallel controlled-phase-flip gate through microcavities

Hyperparallel quantum information processing outperforms its traditional parallel one in terms of channel capacity, low loss rate, and processing speed. We present a way for implementing a robust hyper-parallel optical controlled-phase-flip gate through microcavities. The gate acts on polarization and spatial degrees of freedom (DOFs) simultaneously, and the incomplete and undesired interactions between photons and quantum dots are prevented. Interestingly, the unity fidelity of the gate can be achieved in principle, and the success of the gate is heralded by the single-photon detectors.

quant-ph↗