In nonhydrogenic atoms in a dc electric field, the finite size of the ionic core introduces a coupling between quasibound Stark states that leads to avoided crossings between states that would otherwise cross. Near an avoided crossing, the interacting states may have decay amplitudes that cancel each other, decoupling one of the states from the ionization continuum. This well-known interference...

Adiabatic quantum algorithms represent a promising approach to universal quantum computation. In isolated systems, a key limitation to such algorithms is the presence of avoided level crossings, where gaps become extremely small. In open quantum systems, the fundamental robustness of adiabatic algorithms remains unresolved. Here, we study the dynamics near an avoided level crossing associated w...

Chaotic tunneling in a driven double-well system is investigated in absence as well as in the presence of dissipation. As the constitutive mechanism of chaosassisted tunneling, we focus on the dynamics in the vicinity of three-level crossings in the quasienergy spectrum. They are formed when a tunnel doublet, located on a pair of symmetry-related tori in the classical phase space, approaches a ...

The ultrastrongly coupling (USC) system has very important research significance in quantum simulation and computing. In this paper, the ultranarrow spectrum of a circuit QED with two qubits coupled to single-mode cavity is studied. regime USC, JC model breaks down counter-rotating terms Rabi Hamiltonian leads level anti-crossing energy spectrum. Choosing single-photon driving field at point av...

Abstract We uncover a novel mechanism of superscattering from subwavelength resonators linked to the physics bound states in continuum (BICs). Enhanced scattering occurs due constructive interference within Friedrich-Wintgen interfering resonances. Through this process, cross section single resonance can exceed currently established limit. develop general non-Hermitian model describe resonances...