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Entanglement is a key resource for quantum computing, sensing, and communication, however it is highly susceptible to decoherence. To address this, quantum optics has explored filtering techniques like photon ancillas and Rydberg atom…

While non-Hermitian systems are normally constructed through incoherent coupling to a larger environment, recent works have shown that under certain conditions coherent couplings can be used to similar effect. We show that this new paradigm…

Applied Physics · Physics 2022-10-21 Noah Flemens , Jeffrey Moses

Filtering in spatially-extended dynamical systems is a challenging problem with significant practical applications such as numerical weather prediction. Particle filters allow asymptotically consistent inference but require infeasibly large…

Computation · Statistics 2019-06-04 Matthew M. Graham , Alexandre H. Thiery

A set of Hamiltonians that are not self-adjoint but have the spectrum of the harmonic oscillator is studied. The eigenvectors of these operators and those of their Hermitian conjugates form a bi-orthogonal system that provides a…

Quantum Physics · Physics 2017-11-23 Oscar Rosas-Ortiz , Kevin Zelaya

We study two-dimensional periodic metamaterials in which idealised cylindrical inclusions are modelled by boundary conditions. In the scalar time-harmonic setting, the background field satisfies the Helmholtz equation, and high-contrast…

The non-Hermitian Hamiltonian describes the effective dynamics of a system coupled to a continuously measured bath, and can exhibit anti-unitary symmetries that give rise to exceptional points and broken phases with complex eigenvalues,…

Quantum Physics · Physics 2025-12-23 Sejal Ahuja , Keshav Das Agarwal , Aditi Sen De

In this study, we propose the application of non-Hermitian photonic crystals (PCs) with anisotropic emissions. Unlike a ring of exceptional points (EPs) in isotropic non-Hermitian PCs, the EPs of anisotropic non-Hermitian PCs appear as…

Optics · Physics 2023-03-29 Zhifeng Li , Hai Lin , Rongxin Tang , Haitao Chen , Jiaru Tang , Rui Zhou , Jing Jin , Y. Liu

Parity-time (PT) symmetry has attracted a lot of attention since the concept of pseudo-Hermitian dynamics of open quantum systems was first demonstrated two decades ago. Contrary to their Hermitian counterparts, non-conservative…

Valleytronics aims to control electrons in a valley-specific manner for quantum information manipulation. Due to their strong in-plane anisotropy, which enables polarization-controlled optical transitions to distinct nondegenerate valleys,…

A method for constructing non-uniform filter banks is presented. Starting from a uniform system of translates, generated by a prototype filter, a non-uniform covering of the frequency axis is obtained by composition with a warping function.…

Functional Analysis · Mathematics 2019-12-23 Nicki Holighaus , Christoph Wiesmeyr , Zdeněk Průša

The high sensitivity of the spectrum and wavefunctions to boundary conditions, termed the non-Hermitian skin effect, represents a fundamental aspect of non-Hermitian systems. While it endows non-Hermitian systems with unprecedented physical…

Mesoscale and Nanoscale Physics · Physics 2025-01-30 Nan Cheng , Chang Shu , Kai Zhang , Xiaoming Mao , Kai Sun

Non-Hermitian systems with parity-time symmetry have been found to exhibit real spectra of eigenvalues, indicating a balance between the loss and gain. However, such a balance is not only dependent on the magnitude of loss and gain, but…

Optics · Physics 2020-09-29 Liyou Luo , Jie Luo , Hongchen Chu , Yun Lai

We propose a microscopic translationally invariant glass model which exhibits two level tunneling systems with a broad range of asymmetries and barrier heights in its glassy phase. Their distribution is qualitatively different from what is…

Statistical Mechanics · Physics 2009-11-07 Reimer Kuehn

We propose a scheme to trap and filter electrons, valley dependently, on a scale beyond the diffraction limit, in a gapped Dirac system using a circularly polarized light beam and a microscale metallic resonator. The main mechanism allowing…

Mesoscale and Nanoscale Physics · Physics 2019-01-23 Kevin Dini , Ivan V. Iorsh , Andrey Bogdanov , Ivan A. Shelykh

Together with charge and spin degrees of freedom, many new 2D materials also permit information to be encoded in an electron's valley degree of freedom - that is, in particular momentum states in the material's Brillouin zone. With a view…

Mesoscale and Nanoscale Physics · Physics 2019-03-07 M. Goryca , N. P. Wilson , P. Dey , X. Xu , S. A. Crooker

Two-dimensional transition metal dichalcogenide (TMD) semiconductors provide a unique possibility to access the electronic valley degree of freedom using polarized light, opening the way to valley information transfer between distant…

In this Letter, a tunable valley polarization is investigated for honeycomb systems with broken inversion symmetry such as transition-metal dichalcogenide MX2 (M = Mo, W; X = S, Se) monolayers through elliptical pumping. As compared to…

Mesoscale and Nanoscale Physics · Physics 2014-11-26 Zhigang Song , Ruge Quhe , Yan Li , Ji Feng , Jing Lu , Jinbo Yang

Simulating quantum systems with their environments often requires non-unitary operations, and mapping these to quantum devices often involves expensive dilations or prohibitive measurement costs to achieve desired precisions. Building on…

Quantum Physics · Physics 2025-02-03 Aman Mehta , Scott E. Smart , Joseph Peetz , David A. Mazziotti , Prineha Narang

Kelvin probe force microscopy (KPFM) has been employed to probe charge carriers in a graphene/hexagonal boron nitride (hBN) heterostructure [Nano Lett, 21, 5013 (2021)]. We propose an approach for operating valley filtering based on the…

Mesoscale and Nanoscale Physics · Physics 2023-10-19 A. Belayadi , N. A. Hadadi , P. Vasilopoulos , A. Abbout

Non-Hermiticity appears ubiquitously in various open classical and quantum systems and enriches classification of topological phases. However, the role of nonsymmorphic symmetry, crystalline symmetry accompanying fractional lattice…

Mesoscale and Nanoscale Physics · Physics 2025-04-30 Daichi Nakamura , Yutaro Tanaka , Ken Shiozaki , Kohei Kawabata