We use a quantum path-integral approach to describe the behavior of a microwave cavity coupled to a dissipative mesoscopic circuit. We integrate out the mesoscopic electronic degrees of freedom to obtain a cavity effective action at fourth order in the light/matter coupling. By studying the structure of this action, we establish sufficient conditions in which the cavity dynamics can be described with a Lindblad equation. This equation depends on effective parameters set by electronic correlation functions. It reveals that the mesoscopic circuit induces an effective Kerr interaction and two-photon dissipative processes. We use our method to study the effective dynamics of a cavity coupled to a double quantum dot with normal metal reservoirs. If the cavity is driven at twice its frequency, the double-dot circuit generates photonic squeezing and nonclassicalities visible in the cavity Wigner function. In particular, we find a counterintuitive situation where mesoscopic dissipation enables the production of photonic Schr\"odinger cats. These effects can occur for realistic circuit parameters. Our method can be generalized straightforwardly to more complex circuit geometries with, for instance, multiple quantum dots and other types of fermionic reservoirs such as superconductors and ferromagnets.We use a quantum path-integral approach to describe the behavior of a microwave cavity coupled to a dissipative mesoscopic circuit. We integrate out the mesoscopic electronic degrees of freedom to obtain a cavity effective action at fourth order in the light/matter coupling. By studying the structure of this action, we establish sufficient conditions in which the cavity dynamics can be described with a Lindblad equation. This equation depends on effective parameters set by electronic correlation functions. It reveals that the mesoscopic circuit induces an effective Kerr interaction and two-photon dissipative processes. We use our method to study the effective dynamics of a cavity coupled to a double quantum dot with normal metal reservoirs. If the cavity is driven at twice its frequency, the double-dot circuit generates photonic squeezing and nonclassicalities visible in the cavity Wigner function. In particular, we find a counterintuitive situation where mesoscopic dissipation enables the production of photonic Schr\"odinger cats. These effects can occur for realistic circuit parameters. Our method can be generalized straightforwardly to more complex circuit geometries with, for instance, multiple quantum dots and other types of fermionic reservoirs such as superconductors and ferromagnets.

arXiv:1910.07801Physical review. B./Physical review. BOct 5, 202016 citations

Large- $n$ $O(n)$ with long-range interactions: integrability and resonance dynamicsLarge-$n$ $O(n)$ with long-range interactions: integrability and resonance dynamics

Guido Giachetti, Nicolo Defenu

We study the large- $n$ dynamics of the long-range quantum $O(n)$ model, focusing on the strong long-range regime $α<d$ . The dynamics of the model exhibits non-trivial features on mesoscopic timescales $t\sim\ln N$ , due to the activation of parametric resonances of the nearly degenerate quantum modes. By using recent results establishing the integrability of the large- $n$ limit, we derive the exact resonance conditions and the associated phase diagram, construct the reduced Hamiltonian governing the nonlinear evolution of the resonant sector, and determine the quasiperiodic spectrum of the resulting mesoscopic dynamics. This framework offers a quantitative understanding on how quantum deviation can drive the system away from the mean-field limit. In particular, the presence of multiple resonant modes enhances the logarithmic growth of entanglement and leads to spatially modulated correlations.We study the large-$n$ dynamics of the long-range quantum $O(n)$ model, focusing on the strong long-range regime $α<d$. The dynamics of the model exhibits non-trivial features on mesoscopic timescales $t\sim\ln N$, due to the activation of parametric resonances of the nearly degenerate quantum modes. By using recent results establishing the integrability of the large-$n$ limit, we derive the exact resonance conditions and the associated phase diagram, construct the reduced Hamiltonian governing the nonlinear evolution of the resonant sector, and determine the quasiperiodic spectrum of the resulting mesoscopic dynamics. This framework offers a quantitative understanding on how quantum deviation can drive the system away from the mean-field limit. In particular, the presence of multiple resonant modes enhances the logarithmic growth of entanglement and leads to spatially modulated correlations.

cond-mat.stat-mechCross-listedarXiv:2512.14868Dec 18, 20250 citations

Dynamics of mesoscopic systems: Non-equilibrium Green's functions approach

Václav Špička, Anděla Kalvová, Bedřich Velicky´

Physica E Low-dimensional Systems and NanostructuresAug 16, 20097 citations

COLLAPSE AND REVIVAL EFFECT IN A MESOSCOPIC LC CIRCUIT

Haimei Luo, Yinghua Ji, Jie Liu

This paper studied the time evolution of quantum state in a mesoscopic LC circuit with the coupling energy caused by mesoscopic capacitor acting as a tunnel junction. It indicates that the state of the junction evolves into the quantum superposition of two coherent states and, in the state, nonclassical squeezing properties of the circuit appear. It also indicates that the dynamic behavior of the current shows collapse and revival phenomenon. The research in the paper will be helpful to miniaturize integrate circuits and electric components. It will be also important for the utilization of mesoscopic circuits to evolve the quantum states, which work as information carriers.This paper studied the time evolution of quantum state in a mesoscopic LC circuit with the coupling energy caused by mesoscopic capacitor acting as a tunnel junction. It indicates that the state of the junction evolves into the quantum superposition of two coherent states and, in the state, nonclassical squeezing properties of the circuit appear. It also indicates that the dynamic behavior of the current shows collapse and revival phenomenon. The research in the paper will be helpful to miniaturize integrate circuits and electric components. It will be also important for the utilization of mesoscopic circuits to evolve the quantum states, which work as information carriers.

International Journal of Modern Physics BMar 30, 20041 citation

Mesoscopic Regimes of Temporal Entanglement in Ergodic Quantum Systems

Sergio Cerezo-Roquebrún, Jan Thorben Schneider, Stefano Carignano +4 more

We study temporal correlations in interacting quantum systems through the influence functional of a half-infinite quantum Ising chain. Using Rényi entropies and temporal mutual information, we confirm that integrable dynamics is captured by the quasiparticle picture. In contrast, generic ergodic Hamiltonian dynamics exhibits pronounced deviations from random-circuit universality, and its generalization including a symmetry accounting for energy conservation. Instead, we find a long mesoscopic regime suggestive of a slow spectral reorganization of the influence functional. Our results reveal a rich temporal structure in generic Hamiltonian dynamics and point to limitations of existing random-circuit paradigms at experimentally and numerically relevant timescales.We study temporal correlations in interacting quantum systems through the influence functional of a half-infinite quantum Ising chain. Using Rényi entropies and temporal mutual information, we confirm that integrable dynamics is captured by the quasiparticle picture. In contrast, generic ergodic Hamiltonian dynamics exhibits pronounced deviations from random-circuit universality, and its generalization including a symmetry accounting for energy conservation. Instead, we find a long mesoscopic regime suggestive of a slow spectral reorganization of the influence functional. Our results reveal a rich temporal structure in generic Hamiltonian dynamics and point to limitations of existing random-circuit paradigms at experimentally and numerically relevant timescales.

quant-pharXiv:2605.08356May 12, 20260 citations

Large-

n

O(n)

with long-range interactions: integrability and resonance dynamics

We study the large-

n

dynamics of the long-range quantum

O(n)

model, focusing on the strong long-range regime

α<d

. The dynamics of the model exhibits non-trivial features on mesoscopic timescales

t\sim\ln N

, due to the activation of parametric resonances of the nearly degenerate quantum modes. By using recent results establishing the integrability of the large-

n

limit, we derive the exact resonance conditions and the associated phase diagram, construct the reduced Hamiltonian governing the nonlinear evolution of the resonant sector, and determine the quasiperiodic spectrum of the resulting mesoscopic dynamics. This framework offers a quantitative understanding on how quantum deviation can drive the system away from the mean-field limit. In particular, the presence of multiple resonant modes enhances the logarithmic growth of entanglement and leads to spatially modulated correlations.