arXiv subjects

Zi-Fan Zhu

Publications and source records attributed to Zi-Fan Zhu.

12 recordsLinked to original sources

arXiv2026

Local thermal probe in a one-dimensional chain: An efficient dissipaton-based approach

We study a system consisting of an infinite one-dimensional molecular chain and a locally coupled probe. Starting from the Hamiltonian of the chain-probe composite and the corresponding spectral densities, we evaluate the heat current between the probe and the chain. For this purpose, we develop a dissipaton-based quantum approach that is fully nonperturbative and non-Markovian. The dissipaton algebra yields a set of hierarchically coupled equations of motion for the dissipaton moments, with cross-tier connections in an iterative manner if higher-order chain-probe interactions are included. Numerical results demonstrate the effects of temperature, frequency, onsite energy modification and higher-order couplings on heat transport. This work provides a general framework for thermal transport and other properties in locally probed systems and can be straightforwardly extended to higher-dimensional materials and electronic transport problems with strong many-body effects.

physics.chem-ph↗

arXiv2025

Extended dissipaton theory for higher-order bath couplings and application to non-Condon spectroscopy with anharmonicity

In this work, we develop an extended dissipaton theory that generalizes the environmental couplings beyond the conventional linear and quadratic forms, enabling the treatment of arbitrary order of bath couplings. Applying this theoretical framework to the condensed-phase non-Condon spectroscopy, we demonstrate the interplay of anharmonicity, non-Condon and solvent effects on optical spectra. Precise simulations are carried out with high efficiency on linear absorption spectra involving the above mentioned correlated effects. We exhibit how an anharmonic potential modulates the vibronic feature, offering insights into the role of nonlinear environmental couplings in spectroscopic signatures and exemplifying the success of the extended dissipaton formalism as an exact and efficient method for higher-order bath couplings.

physics.chem-ph↗

arXiv2025

The Phase-Coupled Caldeira-Leggett Model: Non-Markovian Open Quantum Dynamics beyond Linear Dissipation

We introduce the \textit{Phase-Coupled Caldeira-Leggett} (PCL) model of quantum dissipation and develop an exact framework for its dynamics. Unlike the conventional Caldeira-Leggett model with linear system-bath coupling $H_{\mathrm{SB}}\propto\hat F$, the PCL model features an exponential interaction $H_{\mathrm{SB}}\propto e^{iλ\hat F}$, where $\hat F$ denotes the collective bath coordinate. This model unifies concepts from quantum Brownian motion and polaron physics, providing a general platform to study phase-mediated dissipation and decoherence beyond the linear-response regime. Despite its nonlinear system-bath coupling, the Gaussian nature of the environment allows a nonperturbative and non-Markovian treatment of PCL model within the algebra of dissipative quasiparticles. We obtain an exact closed-form equation of motion for the reduced density operator, and numerical simulations reveal distinctive dynamical behaviors that deviate markedly from those predicted by the conventional Caldeira-Leggett model.

quant-ph↗

arXiv2025

Fermionic influence superoperator for transport through Majorana zero modes

In recent years, the study of Majorana signatures in quantum transport has become a central focus in condensed matter physics. Here, we present a rigorous and systematic derivation of the fermionic superoperator describing the open quantum dynamics of electron transport through Majorana zero modes, building on the techniques introduced in Phys. Rev. B 105, 035121 (2022). The numerical implementation of this superoperator is to construct its differential equivalence, the hierarchical equations of motion (HEOM). The HEOM approach describes the system-bath correlated dynamics. Furthermore, we also develop a functional derivative scheme that provides exact expressions for the transport observables in terms of the auxiliary density operators introduced in the HEOM formulation. The superoperator formalism establishes a solid theoretical foundation for analyzing key transport signatures that may uncover the unique characteristics of Majorana physics in mesoscopic systems.

cond-mat.mes-hall↗

arXiv2025

Optimal control on open quantum systems and application to non-Condon photo-induced electron transfer

In this work, we develop an optimal control theory on open quantum system and its environment, and exemplify the method with the application to the non-Condon photo-induced electron transfer (PET) in condensed phase. This method utilizes the dissipaton theory, proposed by Yan in 2014 for open quantum systems, which provides an exact description of the dissipative system while also enables rigorous characterization and control of environmental hybridization modes, fully taking into account the non-perturbative and non-Markovian effects. Leveraging the advantage of the dissipaton phase-space algebra, we present in this communication the theoretical strategy for optimal control on both system and environment simultaneously. The control protocol is successfully demonstrated on PET for the environment-targeted-control facilitated transfer. This work sheds the light on manipulating open systems dynamics via polarized environment.

quant-ph↗

arXiv2025

Correlated vibration-solvent and Duschinsky effects on electron transfer dynamics and optical spectroscopy

Understanding the effects of vibrations in electron transfer (ET) dynamics and optical spectroscopies is essential to precisely interpret the role of decoherence, especially for systems embedded in solvents. In this work, we study the correlated Duschinsky and solvent effects on ET and spectroscopy. Exploited is a novel extended dissipaton-equation-of motion (ext-DEOM) approach, which is an exact and non-Markovian, non-perturbative method for quadratic system-bath couplings. The unified bath description, in terms of multiple Brownian oscillators (BOs), comprises the solvent modes and also intramolecular vibrations. Both ET dynamics and spectroscopy show the complex interplay among linear displacements, frequency shifts, Duschinsky rotations and solvent-induced BO-mode correlations. The reduced ET system density operator evolution is further analyzed in the context of Bloch sphere representation that is basis-set independent due to its geometric nature.

physics.chem-ph↗

arXiv2025

Extended dissipaton theory with application to adatom-graphene composite

In this paper, we present the extended dissipaton theory, including the dissipaton-equation-of-motion formalism and the equivalent dissipaton-embedded quantum master equation. These are exact, non-Markovian, and non-perturbative theories, capable of handling not only linear but also quadratic environmental couplings. These scenarios are prevalent in a variety of strongly correlated electronic systems, including mesoscopic nanodevices and superconductors. As a demonstration, we apply the present theory to simulate the spectral functions of an adatom on a graphene substrate. We analyze the spectral peaks in the presence of the graphene substrate and compare them to those obtained in conventional metal environments. The adatom's spectral functions reveal intricate behaviors arising from the band structure of graphene.

cond-mat.mes-hall↗

arXiv2024

Stability of Quantum Systems beyond Canonical Typicality

Involvement of the environment is indispensable for establishing the statistical distribution of system. We analyze the statistical distribution of a quantum system coupled strongly with a heat bath. This distribution is determined by tracing over the bath's degrees of freedom for the equilibrium system-plus-bath composite. The stability of system distribution is largely affected by the system--bath interaction strength. We propose that the quantum system exhibits a stable distribution only when its system response function in the frequency domain satisfies $\tildeχ(ω= 0+)>0$. We show our results by investigating the non-interacting bosonic impurity system from both the thermodynamic and dynamic perspectives. Our study refines the theoretical framework of canonical statistics, offering insights into thermodynamic phenomena in small-scale systems.

quant-ph↗

arXiv2024

On the relation between momentum uncertainty and thermal wavelength

For quantum particles in a Boltzmann state, we derive an inequality between momentum uncertainty $Δp$ and thermal de Broglie wavelength $λ_{\rm th}$, expressed as $Δp \geq \sqrt{2π}\hbar/λ_{\rm th}$, as a corollary of the Boltzmann lower bound for the Heisenberg uncertainty product proposed in the previous work [EPL, 143, 20001 (2023)]

quant-ph↗

arXiv2024

Quantum Mechanics of Open Systems in Non-Inertial Motion

The study of quantum mechanics in non-inertial reference frames, particularly in the context of open systems, introduces several intriguing phenomena and challenges. This paper presents a comprehensive framework for analyzing the quantum mechanics of open systems undergoing noninertial motion. Our methodology leverages the concept of dissipatons, statistical quasi-particles that capture collective dissipative effects from the environment. We demonstrate that our approach offers a natural understanding of the intricate dynamics among non-inertial effects, decoherence, dissipation, and system-bath entanglement. Specifically, we conduct demonstrations focusing on the Lamb shift phenomenon within a rotating ring cavity. Through theoretical exposition and practical applications, our framework elucidates the profound interplay between open quantum dynamics and non-inertial motion, paving the way for advancements in quantum information processing and sensing technologies.

quant-ph↗

arXiv2022

Coherent excitation energy transfer in model photosynthetic reaction center: Effects of non-Markovian quantum environment

Excitation energy transfer (EET) and electron transfer (ET) are crucially involved in photosynthetic processes. In reality, the photosynthetic reaction center constitutes an open quantum system of EET and ET, which manifests an interplay of pigments, solar light and phonon baths. So far theoretical studies have been mainly based on master equation approaches in the Markovian condition. The non-Markovian environmental effect, which may play a crucial role, has not been sufficiently considered. In this work, we propose a mixed dynamic approach to investigate this open system. The influence of phonon bath is treated via the exact dissipaton equation of motion (DEOM) while that of photon bath is via the Lindblad master equation. Specifically, we explore the effect of non-Markovian quantum phonon bath on the coherent transfer dynamics and its manipulation on the current-voltage behavior. Distinguished from the results of completely Markovian Lindblad equation and those adopting classical environment description, the mixed DEOM-Lindblad simulations exhibit transfer coherence up to a few hundreds femtoseconds and the related environmental manipulation effect on current. These non-Markovian quantum coherent effects be extended tomore complex and realistic systems and be helpful to the design of organic photovoltaic devices.

quant-ph↗

arXiv2021

Temperature-dependence of the subdivision potential in nanothermodynamics

Nanothermodynamics is the thermodynamics of small systems, which are signifcantly affected by their surrounding environments. In nanothermodynamics, Hill introduced the concept of subdivision potential, which charaterizes the non-extensiveness. In this work, we establish the quantum thermodynamic integration of the subdivision potential, which is identifed to be proportional to the difference between the thermal and von Neumann entropies, focusing on its temperature-dependence. As a result, it serves as a versatile tool to help analyze the origin of non-extensiveness in nanosystems.

cond-mat.stat-mech↗