Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Dissipation and decoherence in open nonequilibrium electronic systems

So Takei

Published Jan 1, 2008• 1 citation
OpenAlex

Abstract

We theoretically study steady-state nonequilibrium properties of various open electronic systems subject to time-independent external bias. A charge current is established across each system by\nits coupling to two external particle reservoirs maintained at different chemical potentials. We discuss the impact of intra-reservoir electron correlations on transport, and examine how reservoir-generated dissipation and nonequilibrium-induced decoherence influence these systems.\n\n\nThe effect of intra-lead electron interactions on transport is investigated in the context of a phonon-coupled single molecule transistor driven by Luttinger-liquid source and drain leads. The semi-classical master equation approach is used to compute current and noise characteristics of the device for various interaction strengths in the leads. The results suggest the possibility of tuning the Fano factor of the device using intra-lead electron interactions.\n\n\nThe Keldysh path integral formalism is used to theoretically formulate models that describe the remaining open nonequilibrium systems. We consider voltage-induced electron-phonon scattering and electron mass enhancement due to phonons in a model metallic system. The possibility of adjusting the acoustic phonon velocity\nand the Thomas-Fermi screening length with external voltage is discussed. The effects of dissipation is investigated in an open BCS superconducting graphene, where the dissipation-induced rearrangement of its ground state from the BCS superconductor to the Fermi liquid is examined. The results theoretically infer prospects for a voltage-tuned metal-to-BCS quantum phase transition in graphene. Lastly, we develop a theory of nonequilibrium quantum criticality in open itinerant Ising and Heisenberg magnets. Both departures from equilibrium at conventional quantum critical points and the physics of phase transitions induced by the nonequilibrium drive are analyzed.

Related papers

Nonequilibrium-induced metal-superconductor quantum phase transition in graphene

So Takei, Yong Baek Kim

We study the effects of dissipation and time-independent nonequilibrium drive on an open superconducting graphene. In particular, we investigate how dissipation and nonequilibrium effects modify the semi-metal-BCS quantum phase transition that occurs at half filling in equilibrium graphene with attractive interactions. Our system consists of a graphene sheet sandwiched by two semi-infinite three-dimensional Fermi-liquid reservoirs, which act both as a particle pump/sink and a source of decoherence. A steady-state charge current is established in the system by equilibrating the two reservoirs at different but constant chemical potentials. The graphene sheet is described using the attractive Hubbard model in which the interaction is decoupled in the $s$-wave channel. The nonequilibrium BCS superconductivity in graphene is formulated using the Keldysh path-integral formalism, and we obtain generalized gap and number density equations valid for both zero and finite voltages. The behavior of the gap is discussed as a function of both attractive interaction strength and electron densities for various graphene-reservoir couplings and voltages. We discuss how tracing out the dissipative environment (with or without voltage) leads to decoherence of Cooper pairs in the graphene sheet, hence, to a general suppression of the gap order parameter at all densities. For weak enough attractive interactions we show that the gap vanishes even for electron densities away from half filling and illustrate the possibility of a dissipation-induced metal-superconductor quantum phase transition. We find that the application of small voltages does not alter the essential features of the gap as compared to the case when the system is subject to dissipation alone (i.e., zero voltage). The possibility of tuning the system through the metal-superconductor quantum critical point using voltage is presented.

arXiv:0712.1043•Physical Review B•Oct 2, 2008•15 citations

Non-equilibrium Effects in Dissipative Strongly Correlated Systems

Jiajun Li

Novel physics arises when strongly correlated system is driven out of equilibrium by external fields. Dramatic changes in physical properties, such as conductivity, are empirically observed in strongly correlated materials under high electric field. In particular, electric-field driven metal-insulator transitions are well-known as the resistive switching effect in a variety of materials, such as VO$_2$, V$_2$O$_3$ and other transition metal oxides. To satisfactorily explain both the phenomenology and its underlying mechanism, it is required to model microscopically the out-of-equilibrium dissipative lattice system of interacting electrons. In this thesis, we developed a systematic method of modeling non-equilibrium steady states for dissipative lattice systems by means of Non-equilibrium Green's function and Dynamical Mean Field Theory. We firstly establish a "minimum model" to formulate the strong-field transport in non-interacting dissipative electron lattice. This model is exactly soluble and convenient for discussing energy dissipation and steady-state properties. The formalism is then combined with Dynamical Mean Field Theory to provide a systematic framework describing the nonequilibrium steady-state of correlated materials. We use the formalism to study the strong-field transport properties of correlated materials, Mott insulators and Dirac electrons in graphene. We concentrate on the microscopic description of resistive switching. Of particular interest is the filament formation during the dynamical phase transition, which has been interpreted as a result of the delicate interplay between dissipation and Mott physics. We will also examine $IV$ characteristics and particularly the current saturation of Dirac electrons in graphene. The arXiv version has been updated with minor modifications and corrections.

arXiv:2009.12865•Sep 27, 2020•0 citations

Nonequilibrium Quantum Criticality in Open Electronic Systems

Aditi Mitra, So Takei, Yong Baek Kim +1 more

A theory is presented of quantum criticality in open (coupled to reservoirs) itinerant-electron magnets, with nonequilibrium drive provided by current flow across the system. Both departures from equilibrium at conventional (equilibrium) quantum critical points and the physics of phase transitions induced by the nonequilibrium drive are treated. Nonequilibrium-induced phase transitions are found to have the same leading critical behavior as conventional thermal phase transitions.

arXiv:cond-mat/0607256•Physical Review Letters•Dec 8, 2006•182 citations

Correlated Mott insulators in strong electric fields: Role of phonons in heat dissipation

Tommaso Maria Mazzocchi, Paolo Gazzaneo, Jan Lotze +1 more

We study the spectral and transport properties of a Mott insulator driven by a static electric field into a nonequilibrium steady state. For the dissipation, we consider two mechanisms: wide band fermion reservoirs and phonons included within the Migdal approximation. The electron correlations are treated via nonequilibrium dynamical mean field theory with an impurity solver suitable for strong correlations. We find that dissipation via phonons is limited to restricted ranges of field values around Wannier-Stark resonances. To cover the full range of field strengths, we allow for a small coupling with fermionic baths, which stabilizes the solution. When considering both dissipation mechanisms, we find that phonons enhance the current for field strengths close to half of the gap while lowering it at the gap resonance as compared to the purely electronic dissipation used by Murakami and Werner [Murakami and Werner, Phys. Rev. B 98, 075102 (2018)]. Once phonons are the only dissipation mechanism, the current in the metallic phase is almost one order of magnitude smaller than the typical values obtained by coupling to a fermionic bath. In this case, the transport regime is characterized by an accumulation of charge in the upper Hubbard band described by two effective chemical potentials.

arXiv:2207.01921•Physical review. B./Physical review. B•Sep 15, 2022•12 citations

Nonequilibrium quantum dissipation in spin-fermion systems

Dvira Segal, David R. Reichman, Andrew J. Millis

Dissipative processes in nonequilibrium many-body systems are fundamentally different than their equilibrium counterparts. Such processes are of great importance for the understanding of relaxation in single-molecule devices. As a detailed case study, we investigate here a generic spin-fermion model, where a two-level system couples to two metallic leads with different chemical potentials. We present results for the spin relaxation rate in the nonadiabatic limit for an arbitrary coupling to the leads using both analytical and exact numerical methods. The nonequilibrium dynamics is reflected by an exponential relaxation at long times and via complex phase shifts, leading in some cases to an ``antiorthogonality'' effect. In the limit of strong system-lead coupling at zero temperature we demonstrate the onset of a Marcus-like Gaussian decay with voltage difference activation. This is analogous to the equilibrium spin-boson model, where at strong coupling and high temperatures, the spin excitation rate manifests temperature activated Gaussian behavior. We find that there is no simple linear relationship between the role of the temperature in the bosonic system and a voltage drop in a nonequilibrium electronic case. The two models also differ by the orthogonality-catastrophe factor existing in a fermionic system, which modifies the resulting line shapes. Implications for current characteristics are discussed. We demonstrate the violation of pairwise Coulomb gas behavior for strong coupling to the leads. The results presented in this paper form the basis of an exact, nonperturbative description of steady-state quantum dissipative systems.

arXiv:0708.4372•Physical Review B•Nov 16, 2007•46 citations

Nonequilibrium quantum critical steady state: Transport through a dissipative resonant level

Gu Zhang, Chung‐Hou Chung, Chung-Ting Ke +5 more

Nonequilibrium properties of correlated quantum matter are being intensively investigated because of the rich interplay between external driving and the many-body correlations. Of particular interest is the nonequilibrium behavior near a quantum critical point (QCP), where the system is delicately balanced between different ground states. We present both an analytical calculation of the nonequilibrium steady-state current in a critical system and experimental results to which the theory is compared. The system is a quantum dot coupled to resistive leads: a spinless resonant level interacting with an ohmic dissipative environment. A two channel Kondo-like QCP occurs when the level is on resonance and symmetrically coupled to the leads, conditions achieved by fine-tuning using electrostatic gates. We calculate and measure the nonlinear current as a function of bias ($I$-$V$ curve) at the critical values of the gate voltages corresponding to the QCP. The quantitative agreement between the experimental data and the theory, with no fitting parameter, is excellent. As our system is fully accessible to both theory and experiment, it provides an ideal setting for addressing nonequilibrium phenomena in correlated quantum matter.

arXiv:1609.04765•Physical Review Research•Feb 11, 2021•7 citations
We theoretically study steady-state nonequilibrium properties of various open electronic systems subject to time-independent external bias. A charge current is established across each system by\nits coupling to two external particle reservoirs maintained at different chemical potentials. We discuss the impact of intra-reservoir electron correlations on transport, and examine how reservoir-generated dissipation and nonequilibrium-induced decoherence influence these systems.\n\n\nThe effect of intra-lead electron interactions on transport is investigated in the context of a phonon-coupled single molecule transistor driven by Luttinger-liquid source and drain leads. The semi-classical master equation approach is used to compute current and noise characteristics of the device for various interaction strengths in the leads. The results suggest the possibility of tuning the Fano factor of the device using intra-lead electron interactions.\n\n\nThe Keldysh path integral formalism is used to theoretically formulate models that describe the remaining open nonequilibrium systems. We consider voltage-induced electron-phonon scattering and electron mass enhancement due to phonons in a model metallic system. The possibility of adjusting the acoustic phonon velocity\nand the Thomas-Fermi screening length with external voltage is discussed. The effects of dissipation is investigated in an open BCS superconducting graphene, where the dissipation-induced rearrangement of its ground state from the BCS superconductor to the Fermi liquid is examined. The results theoretically infer prospects for a voltage-tuned metal-to-BCS quantum phase transition in graphene. Lastly, we develop a theory of nonequilibrium quantum criticality in open itinerant Ising and Heisenberg magnets. Both departures from equilibrium at conventional quantum critical points and the physics of phase transitions induced by the nonequilibrium drive are analyzed.
We study the effects of dissipation and time-independent nonequilibrium drive on an open superconducting graphene. In particular, we investigate how dissipation and nonequilibrium effects modify the semi-metal-BCS quantum phase transition that occurs at half filling in equilibrium graphene with attractive interactions. Our system consists of a graphene sheet sandwiched by two semi-infinite three-dimensional Fermi-liquid reservoirs, which act both as a particle pump/sink and a source of decoherence. A steady-state charge current is established in the system by equilibrating the two reservoirs at different but constant chemical potentials. The graphene sheet is described using the attractive Hubbard model in which the interaction is decoupled in the sss-wave channel. The nonequilibrium BCS superconductivity in graphene is formulated using the Keldysh path-integral formalism, and we obtain generalized gap and number density equations valid for both zero and finite voltages. The behavior of the gap is discussed as a function of both attractive interaction strength and electron densities for various graphene-reservoir couplings and voltages. We discuss how tracing out the dissipative environment (with or without voltage) leads to decoherence of Cooper pairs in the graphene sheet, hence, to a general suppression of the gap order parameter at all densities. For weak enough attractive interactions we show that the gap vanishes even for electron densities away from half filling and illustrate the possibility of a dissipation-induced metal-superconductor quantum phase transition. We find that the application of small voltages does not alter the essential features of the gap as compared to the case when the system is subject to dissipation alone (i.e., zero voltage). The possibility of tuning the system through the metal-superconductor quantum critical point using voltage is presented.
Novel physics arises when strongly correlated system is driven out of equilibrium by external fields. Dramatic changes in physical properties, such as conductivity, are empirically observed in strongly correlated materials under high electric field. In particular, electric-field driven metal-insulator transitions are well-known as the resistive switching effect in a variety of materials, such as VO2_22​, V2_22​O3_33​ and other transition metal oxides. To satisfactorily explain both the phenomenology and its underlying mechanism, it is required to model microscopically the out-of-equilibrium dissipative lattice system of interacting electrons. In this thesis, we developed a systematic method of modeling non-equilibrium steady states for dissipative lattice systems by means of Non-equilibrium Green's function and Dynamical Mean Field Theory. We firstly establish a "minimum model" to formulate the strong-field transport in non-interacting dissipative electron lattice. This model is exactly soluble and convenient for discussing energy dissipation and steady-state properties. The formalism is then combined with Dynamical Mean Field Theory to provide a systematic framework describing the nonequilibrium steady-state of correlated materials. We use the formalism to study the strong-field transport properties of correlated materials, Mott insulators and Dirac electrons in graphene. We concentrate on the microscopic description of resistive switching. Of particular interest is the filament formation during the dynamical phase transition, which has been interpreted as a result of the delicate interplay between dissipation and Mott physics. We will also examine IVIVIV characteristics and particularly the current saturation of Dirac electrons in graphene. The arXiv version has been updated with minor modifications and corrections.
We study the spectral and transport properties of a Mott insulator driven by a static electric field into a nonequilibrium steady state. For the dissipation, we consider two mechanisms: wide band fermion reservoirs and phonons included within the Migdal approximation. The electron correlations are treated via nonequilibrium dynamical mean field theory with an impurity solver suitable for strong correlations. We find that dissipation via phonons is limited to restricted ranges of field values around Wannier-Stark resonances. To cover the full range of field strengths, we allow for a small coupling with fermionic baths, which stabilizes the solution. When considering both dissipation mechanisms, we find that phonons enhance the current for field strengths close to half of the gap while lowering it at the gap resonance as compared to the purely electronic dissipation used by Murakami and Werner [Murakami and Werner, Phys. Rev. B 98, 075102 (2018)]. Once phonons are the only dissipation mechanism, the current in the metallic phase is almost one order of magnitude smaller than the typical values obtained by coupling to a fermionic bath. In this case, the transport regime is characterized by an accumulation of charge in the upper Hubbard band described by two effective chemical potentials.
Dissipative processes in nonequilibrium many-body systems are fundamentally different than their equilibrium counterparts. Such processes are of great importance for the understanding of relaxation in single-molecule devices. As a detailed case study, we investigate here a generic spin-fermion model, where a two-level system couples to two metallic leads with different chemical potentials. We present results for the spin relaxation rate in the nonadiabatic limit for an arbitrary coupling to the leads using both analytical and exact numerical methods. The nonequilibrium dynamics is reflected by an exponential relaxation at long times and via complex phase shifts, leading in some cases to an ``antiorthogonality'' effect. In the limit of strong system-lead coupling at zero temperature we demonstrate the onset of a Marcus-like Gaussian decay with voltage difference activation. This is analogous to the equilibrium spin-boson model, where at strong coupling and high temperatures, the spin excitation rate manifests temperature activated Gaussian behavior. We find that there is no simple linear relationship between the role of the temperature in the bosonic system and a voltage drop in a nonequilibrium electronic case. The two models also differ by the orthogonality-catastrophe factor existing in a fermionic system, which modifies the resulting line shapes. Implications for current characteristics are discussed. We demonstrate the violation of pairwise Coulomb gas behavior for strong coupling to the leads. The results presented in this paper form the basis of an exact, nonperturbative description of steady-state quantum dissipative systems.
Nonequilibrium properties of correlated quantum matter are being intensively investigated because of the rich interplay between external driving and the many-body correlations. Of particular interest is the nonequilibrium behavior near a quantum critical point (QCP), where the system is delicately balanced between different ground states. We present both an analytical calculation of the nonequilibrium steady-state current in a critical system and experimental results to which the theory is compared. The system is a quantum dot coupled to resistive leads: a spinless resonant level interacting with an ohmic dissipative environment. A two channel Kondo-like QCP occurs when the level is on resonance and symmetrically coupled to the leads, conditions achieved by fine-tuning using electrostatic gates. We calculate and measure the nonlinear current as a function of bias (III-VVV curve) at the critical values of the gate voltages corresponding to the QCP. The quantitative agreement between the experimental data and the theory, with no fitting parameter, is excellent. As our system is fully accessible to both theory and experiment, it provides an ideal setting for addressing nonequilibrium phenomena in correlated quantum matter.