Quantum Otto cycle in the Anderson impurity model

We study the thermodynamic performance of a periodic quantum Otto cycle operating on the single-impurity Anderson model. Using a decomposition of the time-evolution generator based on the principle of minimal dissipation, combined with the numerically exact hierarchical equations of motion (HEOM) method, we analyze the operating regimes of the quantum thermal machine and investigate effects of Coulomb interactions, strong system-reservoir coupling, and energy level alignments. Our results show that Coulomb interaction can change the operating regimes and may lead to an enhancement of the efficiency.

💡 Research Summary

This paper investigates the performance of a quantum Otto engine whose working medium is the single‑impurity Anderson model (SIAM). The authors combine two advanced theoretical tools: (i) a decomposition of the time‑dependent generator of the reduced dynamics based on the principle of minimal dissipation, which yields a uniquely defined effective Hamiltonian (K_S(t)) and a minimized dissipator, and (ii) the hierarchical equations of motion (HEOM) method, which provides numerically exact solutions for open quantum systems even in the strong‑coupling, non‑Markovian regime.

The total Hamiltonian consists of the SIAM system part (H_S(t)=\varepsilon(t)\sum_\sigma d^\dagger_\sigma d_\sigma + U d^\dagger_\uparrow d_\uparrow d^\dagger_\downarrow d_\downarrow), two fermionic reservoirs (hot and cold) with Lorentzian spectral densities (J_K(\epsilon)=\Gamma W^2/