3 papers
quant-ph2026
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…
quant-ph2026
Exact treatment of the memory kernel under time-dependent system-environment coupling via a train of delta distributions
Yuta Uenaga, Kensuke Gallock-Yoshimura, Takano Taira
Memory effects in a quantum system coupled to an environment are one of the central features in the theory of open quantum systems. The dynamics of such quantum systems are typical…
quant-ph2025
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…