Dynamically encircling an exceptional point through phase-tracked closed-loop control

• URL: http://arxiv.org/abs/2509.04940v1
• Date: Fri, 05 Sep 2025 09:03:29 GMT
• Title: Dynamically encircling an exceptional point through phase-tracked closed-loop control
• Authors: Sen Zhang, Yangyu Huang, Lei Yu, Kaixuan He, Ning Zhou, Dingbang Xiao, Xuezhong Wu, Franco Nori, Hui Jing, Xin Zhou,
• Abstract summary: We propose an approach leveraging the phase-locked loop (PLL) technique to facilitate smooth, dynamic encircling of exceptional points (EPs)<n>This study advances the concept of phase-tracked dynamical encircling and explores its practical implementation within a fully electrically controlled non-Hermitian microelectromechanical system.
• Score: 12.487007323445146
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: The intricate complex eigenvalues of non-Hermitian Hamiltonians manifest as Riemann surfaces in control parameter spaces. At the exceptional points (EPs), the degeneracy of both eigenvalues and eigenvectors introduces noteworthy topological features, particularly during the encirclement of the EPs. Traditional methods for probing the state information on the Riemann surfaces involve static measurements; however, realizing continuous encircling remains a formidable challenge due to non-adiabatic transitions that disrupt the transport paths. Here we propose an approach leveraging the phase-locked loop (PLL) technique to facilitate smooth, dynamic encircling of EPs while maintaining resonance. Our methodology strategically ties the excitation frequencies of steady states to their response phases, enabling controlled traversal along the Riemann surfaces of real eigenvalues. This study advances the concept of phase-tracked dynamical encircling and explores its practical implementation within a fully electrically controlled non-Hermitian microelectromechanical system, highlighting robust in-situ tunability and providing methods for exploring non-Hermitian topologies.

Related papers

• Theory of the Uhlmann Phase in Quasi-Hermitian Quantum Systems [5.939358559376569]
  We develop a theory of the Uhlmann phase for quasi-Hermitian systems, where the physical Hilbert space metric varies with external parameters.<n>We uncover rich finite-temperature topological phase diagrams, including multiple transitions between trivial and nontrivial phases driven by thermal fluctuations.<n>This work establishes a unified framework for understanding mixed-state geometric phases in non-Hermitian quantum systems.
  arXiv  Detail & Related papers  (2026-03-02T14:25:32Z)
• Observation of non-Hermitian topology in cold Rydberg quantum gases [42.41909362660157]
  We experimentally demonstrate non-Hermitian spectra topology in a dissipative Rydberg atomic gas.<n>By increasing the interaction strength, the system evolves from Hermitian to non-Hermitian regime.<n>This work establishes cold Rydberg gases as a versatile platform for exploring the rich interplay between non-Hermitian topology, strong interactions, and dissipative quantum dynamics.
  arXiv  Detail & Related papers  (2025-09-30T13:44:43Z)
• Forecasting Continuous Non-Conservative Dynamical Systems in SO(3) [51.510040541600176]
  We propose a novel approach to modeling the rotation of moving objects in computer vision.<n>Our approach is agnostic to energy and momentum conservation while being robust to input noise.<n>By learning to approximate object dynamics from noisy states during training, our model attains robust extrapolation capabilities in simulation and various real-world settings.
  arXiv  Detail & Related papers  (2025-08-11T09:03:10Z)
• Direct Measurement of Zak Phase and Higher Winding Numbers in an Electroacoustic Cavity System [0.2796197251957245]
  We propose an experimental method for the direct measurement of topological invariants via adiabatic state evolution.<n>We successfully observe the quantized Zak phase in both the conventional Su-Schrieffer-Heeger model and its extension incorporating next-nearest-neighbor coupling.
  arXiv  Detail & Related papers  (2025-05-27T12:46:17Z)
• Non-Hermitian topology and skin modes in the continuum via parametric processes [44.99833362998488]
  We show that Hermitian, nonlocal parametric pairing processes can induce non-Hermitian topology and skin modes.<n>Our model, stabilized by local dissipation, reveals exceptional points that spawn a tilted diabolical line in the dispersion.
  arXiv  Detail & Related papers  (2025-05-05T16:38:20Z)
• Indication of critical scaling in time during the relaxation of an open quantum system [34.82692226532414]
  Phase transitions correspond to the singular behavior of physical systems in response to continuous control parameters like temperature or external fields. Near continuous phase transitions, associated with the divergence of a correlation length, universal power-law scaling behavior with critical exponents independent of microscopic system details is found.
  arXiv  Detail & Related papers  (2022-08-10T05:59:14Z)
• Accessing the topological Mott insulator in cold atom quantum simulators with realistic Rydberg dressing [58.720142291102135]
  We investigate a realistic scenario for the quantum simulation of such systems using cold Rydberg-dressed atoms in optical lattices. We perform a detailed analysis of the phase diagram at half- and incommensurate fillings, in the mean-field approximation. We furthermore study the stability of the phases with respect to temperature within the mean-field approximation.
  arXiv  Detail & Related papers  (2022-03-28T14:55:28Z)
• Decimation technique for open quantum systems: a case study with driven-dissipative bosonic chains [62.997667081978825]
  Unavoidable coupling of quantum systems to external degrees of freedom leads to dissipative (non-unitary) dynamics. We introduce a method to deal with these systems based on the calculation of (dissipative) lattice Green's function. We illustrate the power of this method with several examples of driven-dissipative bosonic chains of increasing complexity.
  arXiv  Detail & Related papers  (2022-02-15T19:00:09Z)
• Engineering Dissipative Quasicrystals [7.182858821473896]
  We discuss the systematic engineering of quasicrystals in open quantum systems where quasiperiodicity is introduced through purely dissipative processes. Our work suggests a systematic route toward engineering exotic quantum dynamics in open systems, based on insights of non-Hermitian physics.
  arXiv  Detail & Related papers  (2021-11-29T10:35:34Z)
• Generalized Discrete Truncated Wigner Approximation for Nonadiabtic Quantum-Classical Dynamics [0.0]
  We introduce a linearized semiclassical method, the generalized discrete truncated Wigner approximation (GDTWA) GDTWA samples the electron degrees of freedom in a discrete phase space, and forbids an unphysical growth of electronic state populations. Our results suggest that the method can be very adequate to treat challenging nonadiabatic dynamics problems in chemistry and related fields.
  arXiv  Detail & Related papers  (2021-04-14T21:53:35Z)
• Probing non-Hermitian phase transitions in curved space via quench dynamics [0.0]
  Non-Hermitian Hamiltonians are relevant to describe the features of a broad class of physical phenomena. We study the interplay of geometry and non-Hermitian dynamics by unveiling the existence of curvature-dependent non-Hermitian phase transitions.
  arXiv  Detail & Related papers  (2020-12-14T19:47:59Z)
• Chiral state conversion in a levitated micromechanical oscillator with in situ control of parameter loops [13.570675757915422]
  We propose an easy-controllable levitated microparticle system that carries a pair of exceptional points (EPs) and realize slow evolution of the Hamiltonian along loops in the parameter plane. We demonstrate that, under the joint action of topological structure of energy surfaces and nonadiabatic transitions (NATs), the chiral behavior emerges both along a loop encircling an EP and even along a straight path away from the EP.
  arXiv  Detail & Related papers  (2020-10-21T10:04:51Z)
• Probing eigenstate thermalization in quantum simulators via fluctuation-dissipation relations [77.34726150561087]
  The eigenstate thermalization hypothesis (ETH) offers a universal mechanism for the approach to equilibrium of closed quantum many-body systems. Here, we propose a theory-independent route to probe the full ETH in quantum simulators by observing the emergence of fluctuation-dissipation relations. Our work presents a theory-independent way to characterize thermalization in quantum simulators and paves the way to quantum simulate condensed matter pump-probe experiments.
  arXiv  Detail & Related papers  (2020-07-20T18:00:02Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.