Critical points in two-channel quantum systems

Abstract

Calculations for open quantum systems are performed usually by taking into account their embedding into one common environment, which is mostly the common continuum of scattering wavefunctions. Realistic quantum systems are coupled however often to more than one continuum. For example, the conductance of an open cavity needs at least two environments, namely the input and the output channel. In the present paper, we study generic features of the transfer of particles through an open quantum system coupled to two channels. We compare the results with those characteristic of a one-channel system. Of special interest is the parameter range which is influenced by singular points. Here, the states of the system are mixed via the environment. In the one-channel case, the resonance structure of the cross section is independent of the existence of singular points. In the two-channel case, however, new effects appear caused by coherence. An example is the enhanced conductance of an open cavity in a certain finite parameter range. It is anti-correlated with the phase rigidity of the eigenfunctions of the non-Hermitian Hamilton operator.

22 pages, 4 figures; paper revised, results are unchanged

References in corpus (10)

• A review of progress in the physics of open quantum systems: theory and experiment
• Resonances in open quantum systems
• Clustering of exceptional points and dynamical phase transitions
• Experimental Width Shift Distribution: A Test of Nonorthogonality for Local and Global Perturbations
• Phase rigidity and avoided level crossings in the complex energy plane
• Correlated behavior of conductance and phase rigidity in the transition from the weak-coupling to the strong-coupling regime
• Linear Quantum Entropy and Non-Hermitian Hamiltonians
• Gain and loss in open quantum systems
• Equilibrium states in open quantum systems
• Detecting weak coupling in mesoscopic systems with a nonequilibrium Fano resonance

Cited by in corpus (2)

• Observation of slowly decaying eigenmodes without exceptional points in Floquet, dissipative, synthetic circuits
• Dynamics of finite dimensional non-hermitian systems with indefinite metric