A topologically protected quantum dynamo effect in a driven spin-boson model ...

• Main Authors: Bernhardt, Ephraim, Elouard, Cyril, Hur, Karyn Le
• Format: Text
• Language: unknown
• Published: arXiv 2022
• Subjects: Quantum Physics quant-ph; Mesoscale and Nanoscale Physics cond-mat.mes-hall; FOS Physical sciences; South Pole; South pole
• Online Access: https://dx.doi.org/10.48550/arxiv.2208.01707; https://arxiv.org/abs/2208.01707

We describe a quantum dynamo effect in a driven system coupled to a harmonic oscillator describing a cavity mode or to a collection of modes forming an Ohmic bosonic bath. When the system Hamiltonian changes in time, this induces a dynamical field in the bosonic modes having resonant frequencies with the driving velocity. This field opposes the change of the external driving field in a way reminiscent of Faraday's law of induction, justifying the term 'quantum dynamo effect'. For the specific situation of a periodically driven spin-$\frac{1}{2}$ on the Bloch sphere, we show that the work done by rolling the spin from north to south pole can efficiently be converted into a coherent displacement of the resonant bosonic modes, the effect thus corresponds to a work-to-work conversion and allows to interpret this transmitted energy into the bath as work. We study this effect, its performance and limitations in detail for a driven spin-$\frac{1}{2}$ in the presence of a radial magnetic field addressing a relation ... : 35 pages, 14 figures ...