2 citations · 2 across the 5 of their papers we have counts for
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Driving collective RPA modes by a time-dependent Dyson map
Andreas Fring, Marta Reboiro
We study a time-dependent non-Hermitian generalisation of the Schütte-Da~Providência model describing a bosonic mode coupled to collective particle-hole excitations. Using a time…
Hidden symmetry and Jordan chains in a resonant ghostly three-dimensional model
Andreas Fring, Ian Marquette
We investigate a three-dimensional ghostly Hamiltonian realisation of the fully degenerate resonant sixth-order Pais-Uhlenbeck oscillator. On the classical level, the phase-space f…
Bounded Dyson maps and cavity-driven transitions in a time-dependent non-Hermitian spin-boson model
Andreas Fring, Marta Reboiro
We study a time-dependent non-Hermitian extension of the Schütte-Da Providência spin-boson Hamiltonian with complex couplings. A time-dependent Dyson map relates the model to a Her…
Quantum-classical diagnostics and Bohmian inequivalence for higher time-derivative Hamiltonians
Sanjib Dey, Andreas Fring
We develop a Bohmian analysis of a two-dimensional ghost Hamiltonian and its mapping to the degenerate Pais-Uhlenbeck model. Using Gaussian wavepackets, we derive the corresponding…
Spectrum-generating algebra and intertwiners of the resonant Pais-Uhlenbeck oscillator
Andreas Fring, Ian Marquette, Takano Taira
We study the quantum Pais-Uhlenbeck oscillator at the resonant (equal-frequency) point, where the dynamics becomes non-diagonalisable and the conventional Fock-space construction c…
Ghost-Free Quantisation of Higher Time-Derivative Theories via Non-Unitary Similarity Transformations
Andreas Fring, Takano Taira, Bethan Turner
We address the long-standing ``ghost problem" in higher time-derivative theories (HTDTs), where quantisation typically yields sectors with either unbounded spectra or non-normalisa…