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I am interested to uncover phenomena related to the dynamics of electrons and photons in small quantum systems.

A recent highlight are topological lasers, theoretically proposed in Opt. Lett. 38, 1912 (2013) and realized in experimental collaboration in Nat. Commun. 9, 981 (2018), which are part of my studies of topological photonics since 2012. I also work on quantum dissipative systems and quantum noise (since 1993), quantum chaos (since 1994), mesoscopic conductors and superconductors (since 1999), Anderson localization (since 2000), dielectric resonators (since 2002), atoms in strong fields (since 2002), graphene (since 2007), PT-symmetric optics (since 2010), Majorana states (since 2012) and many-body localization (since 2015), where I frequently employ random-matrix theory, scattering approaches, and semiclassical methods.

Below you find a breakdown of fields of activity in terms of different categories; see publications for details and results.

systems

photonic systems

  • topological photonics
  • PT symmetric and nonhermitian optics
  • structured microlasers
  • dielectric microresonators
  • random media

mesoscopic systems

  • topological superconductors
  • topological insulators
  • graphene and Dirac materials
  • mesoscopic superconductors
  • quantum dots and wires
  • quantum information devices
  • metameterials

interacting systems

  • interacting fermions
  • spin chains
  • Coulomb blockaded systems

quantum and atom optical systems

  • mesoscopic light emitters
  • exciton polaritons
  • quantum condensates
  • atoms in pulsed optical fields
  • atoms in strong fields (NSDI, ATI, HHG)

quantum dynamical systems

  • quantum billiards
  • kicked systems
  • quantum walks

classical dynamical systems

  • fully chaotic systems
  • mixed chaotic systems
  • random dynamical systems

concepts

topological states

  • edge and defect states
  • Majorana fermions
  • flat bands and compactons
  • topological mode selection
  • nonhermitian and nonlinear protected states

quantum coherent transport

  • effects of bandstructure topology
  • Anderson localization
  • weak localization
  • coherent backscattering
  • sample-to-sample fluctuations
  • pseudomagnetic fields
  • contacts and interfaces
  • confinement mechanisms
  • adsorbate functionalization and sensing
  • spin and pseudospin effects
  • proximity effect
  • Josephson effect
  • Aharonov-Bohm effect
  • quantum pumping
  • delay times

quantum noise

  • shot noise
  • full counting statistics
  • quantum limited noise
  • nonmarkovian and nonergodic noise

interactions

  • many-body localization
  • entanglement and correlations
  • dissipation and decoherence
  • amplification and lasing
  • light-matter interactions
  • Coulomb blockade
  • space charge effects
  • charge ordering
  • nonequilibrium dynamics
  • nonlinear wave dynamics

resonance phenomena

  • quantum decay
  • exceptional points
  • mode nonorthogonality
  • fractal Weyl law
  • nonhermitian symmetries

quantum-to-classical correspondence

  • quantum chaos
  • mixed phase space
  • bifurcations
  • Ehrenfest time
  • scarring
  • wave corrections
  • Goos-Hänchen shift

methods

scattering theory

  • Landauer-Büttiker formalism
  • Green's function methods
  • kinetic theory
  • non-hermitian operators

statistical approaches

  • random matrices
  • large deviation statistics
  • fluctuation theorems
  • multifractality
  • nonergodicity
  • universal singular fluctuations

semiclassics

  • uniform approximations
  • asymptotic boundary layer method
  • phase-space representations

many-body and field theory

  • one-particle density matrix
  • Bogoliubov theory
  • Master equations
  • T matrix and vertex functions
  • nonlinear sigma model
  • Keldysh techniques
  • path integrals

numerics

  • exact diagonalization and propagation
  • recursive Green's functions and decimation
  • tensor networks and matrix product states
  • quantum equations of motion
  • tight-binding and coupled-mode approaches
  • full-wave modelling

experimental collaborations

  • dielectric resonator chains
  • exciton polaritons in structured devices
  • photonic lattices
  • optical quantum walks
  • semiconductor microlasers