arXiv subjects

Bernard Faulend

Publications and source records attributed to Bernard Faulend.

3 recordsLinked to original sources

arXiv2026

Quantum Beats in Many-Body Localized Systems

Slow particle dynamics observed numerically even deep inside the many-body localized (MBL) regime has called the stability of MBL in the thermodynamic limit into question, and its microscopic origin remains unknown. Here, we show that this slow dynamics originates from many-body quantum beats that arise from the interaction-induced modulation of oscillations associated with single-particle hopping processes. We relate this mechanism to local integrals of motion (LIOMs) and show that it survives at arbitrarily large distances between LIOMs, is consistent with the stability of MBL in the thermodynamic limit, and is generic to many-body systems. We present new numerical results for quasiperiodic potentials and, based on the quantum beats mechanism, develop an analytical model that explains number entropy growth and quasiparticle spreading, as well as clarifies the distinct MBL phenomenology observed in quasiperiodic and random potentials. Lastly, we propose concrete signatures for observing many-body quantum beats in existing experimental platforms.

cond-mat.dis-nn↗

arXiv2025

Quantum theory of electrically levitated nanoparticle-ion systems: Motional dynamics and sympathetic cooling

We develop the theory describing the quantum coupled dynamics of the center-of-mass motion of a nanoparticle and an ensemble of ions co-trapped in a dual-frequency linear Paul trap. We first derive analytical expressions for the motional frequencies and classical trajectories of both nanoparticle and ions. We then derive a quantum master equation for the ion-nanoparticle system and quantify the sympathetic cooling of the nanoparticle motion enabled by its Coulomb coupling to a continuously Doppler-cooled ion. We predict that motional cooling down to sub-kelvin temperatures is achievable in state-of-the-art experiments even in the absence of motional feedback and in the presence of micromotion. We then extend our analysis to an ensemble of $N$ ions, predicting a linear increase of the cooling rate as a function of $N$ and motional cooling of the nanoparticle down to tenths of millikelvin in current experimental platforms. Our work establishes the theoretical toolbox needed to explore the ion-assisted preparation of non-Gaussian motional states of levitated nanoparticles.

quant-ph↗

arXiv2022

Tunnelling of a composite particle in presence of a magnetic field

We present a simple model of composite particle tunnelling through a rectangular potential barrier in presence of magnetic field. The exact numerical solution of the problem is provided and the applicability to real physical situations is discussed. Some qualitative features of tunnelling with no magnetic interaction are retained, but some new ones are also observed. The resonance peaks in transmission spectrum generally do not reach $100\%$ transmission probability when the magnetic field is turned on. We observe splitting and in some cases widening of transmission probability peaks. When the width $b$ of area with magnetic field is large, we observe oscillations of spin-flip probability with energy and $b$ which are caused by Larmor precession of spin about the vector of magnetic field. For some values of relevant parameters we also observe significant increase of tunnelling probability for low energies in the single particle case.

quant-ph↗