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

Adiabatic decoherence : the role of a spin bath

Anthony Macchiavello

Published Jan 1, 2004• 0 citations
OpenAlex

Abstract

In this thesis we investigate the decoherence of a system interacting with a spin bath. This thesis is primarily concerned with certain properties of the bath that can be used to control decohe ...

Related papers

Suppression of decoherence in a generalization of the spin-bath model

Mario Castagnino, Sebastián Fortín, Olímpia Lombardi

The works on decoherence due to spin baths usually agree in studying a one-spin system in interaction with a large spin bath. In this paper we generalize those models by analyzing a many-spin system and by studying decoherence or its suppression in function of the relation between the numbers of spins of the system and the bath. This model may help to identify clusters of particles unaffected by decoherence, which, as a consequence, can be used to store quantum information.

arXiv:1001.3537•Journal of Physics A Mathematical and Theoretical•Jan 20, 2010•40 citations

Adiabatic quantum decoherence in many non-interacting subsystems induced by the coupling with a common boson bath

H. H. Segnorile, Cecilia E. González, R. C. Zamar

arXiv:1912.12993•Annals of Physics•Nov 1, 2021•1 citation

What are the systems that decohere?

Mario Castagnino, Sebastián Fortín, Olímpia Lombardi

The fact that the Environment Induced Decoherence approach offers no general criterion to decide where to place the "cut" between system and environment has been considered as a serious conceptual problem of the proposal. In this letter we argue that this is actually a pseudo-problem, which is dissolved by the fact that decoherence is a phenomenon relative to the relevant observables selected by the measuring arrangement. We also show that, when the spin-bath model is studied from this perspective, certain unexpected results are obtained, as that of a system decohering in interaction with a very small environment.

arXiv:1002.3913•Feb 20, 2010•1 citation

Decoherence and entanglement in single molecule magnets

Özgür Bozat

Single molecule magnets are novel mesoscopic materials exhibiting both classical and quantum properties. Revealing the decoherence and entanglement mechanisms in these systems is crucial for the applications in quantum information technologies. In this thesis, quantum tunneling of magnetization is studied in single molecule magnet dimer [Mn4]2. Motivated by the recent experiments demanding the modification of the current theories, phonon mediated spin bath decoherence model is proposed. In the first part of the thesis, the magnetization of the [Mn4]2 dimer under external magnetic field is investigated. Alternative entangled spin states involved in quantum tunnelings are identified by means of the exact solution of the Schrödinger equation and the Landau-Zener-Stückelberg method. Later, a decoherence model is introduced in which the interaction between the single molecule magnet (central spin) and spin bath is mediated by phonons in a coherent state or thermal distribution. It is observed that the decoherence factor decays in a Gaussian fashion and it becomes independent of the phonon frequencies at short times for coherent states and low temperature thermal distribution. In the former case, if the phonon energies are much larger than spin-phonon coupling or bath spins are fully polarized, decoherence time becomes independent of the initial phonon state. For the thermal state case, phonons play more important role in decoherence with increasing temperature. Possible effects of the temperature on spin bath contribution to decoherence is discussed. Then, the effect of entangled environment on decoherence is analyzed. Entanglement within environment is shown to reduce the decoherence of central spin. Also, the entanglement dynamics of the central bipartite spin system is studied. Classification of the Bell states is examined for common spin bath, and separate spin baths. Last part of the thesis is the analysis of dephasing in entangled qutrits (three level quantum systems) under the classical noise, and quantum decoherence. Density matrix formalism is shown to give equivalent results for both cases. For common and separate baths, robust and fragile Bell-like qutrit states were determined, and Horodecki's bound entangled state is shown to be more robust to decoherence in the latter case.

•Jan 1, 2008•0 citations

Analyzing the spin-bath model without simulations

Sebastián Fortín, Olímpia Lombardi

On the basis of a lemma designed to decide whether a discrete system decoheres or not with no need of computer simulations, in this paper we analyze the well-known spin-bath model. The lemma allows us to predict the decoherence of the system by analytical means.

arXiv:1010.3254•Oct 15, 2010•1 citation

Relaxation of antiferromagnetic order and growth of Rényi entropy in a generalized Heisenberg star

Jiaxiu Li, Ye Cao, Ning Wu

Interacting central spin systems, in which a central spin is coupled to a strongly correlated spin bath with intrabath interaction, consist of an important class of spin systems beyond the usual Gaudin magnet. These systems are relevant to several realistic setups and serve as an interesting platform to study interaction controlled decoherence and frustration induced instability of magnetic order. Using an equations-of-motion method based on analytical representations of spin-operator matrix elements in the XX chain, we obtain exact long-time dynamics of a generalized Heisenberg star consisting of a spin-$S$ central spin and an inhomogeneously coupled XXZ chain of $N\ensuremath{\le}16$ bath spins. In contrast to previous studies where the central spin dynamics is mainly concerned, we focus on the influence of the central spin on the dynamics of magnetic orders within the spin bath. By preparing the XXZ bath in a N\'eel state, we find that in the gapless phase of the bath even weak system-bath coupling could lead to nearly perfect relaxation of the antiferromagnetic order. In the gapped phase, the staggered magnetization decays rapidly and approaches a steady value that increases with increasing anisotropy parameter. These findings suggest the possibility of controlling internal dynamics of strongly correlated many-spin systems by certain coupled auxiliary systems of even few degrees of freedom. We also study the dynamics of the R\'enyi entanglement entropy of the central spin when the bath is prepared in the ground state. Both the overall profile and initial growth rate of the R\'enyi entropy are found to exhibit minima at the critical point of the XXZ bath.

arXiv:2108.07055•Physical review. B./Physical review. B•Jul 5, 2022•2 citations
The fact that the Environment Induced Decoherence approach offers no general criterion to decide where to place the "cut" between system and environment has been considered as a serious conceptual problem of the proposal. In this letter we argue that this is actually a pseudo-problem, which is dissolved by the fact that decoherence is a phenomenon relative to the relevant observables selected by the measuring arrangement. We also show that, when the spin-bath model is studied from this perspective, certain unexpected results are obtained, as that of a system decohering in interaction with a very small environment.
Single molecule magnets are novel mesoscopic materials exhibiting both classical and quantum properties. Revealing the decoherence and entanglement mechanisms in these systems is crucial for the applications in quantum information technologies. In this thesis, quantum tunneling of magnetization is studied in single molecule magnet dimer [Mn4]2. Motivated by the recent experiments demanding the modification of the current theories, phonon mediated spin bath decoherence model is proposed. In the first part of the thesis, the magnetization of the [Mn4]2 dimer under external magnetic field is investigated. Alternative entangled spin states involved in quantum tunnelings are identified by means of the exact solution of the Schrödinger equation and the Landau-Zener-Stückelberg method. Later, a decoherence model is introduced in which the interaction between the single molecule magnet (central spin) and spin bath is mediated by phonons in a coherent state or thermal distribution. It is observed that the decoherence factor decays in a Gaussian fashion and it becomes independent of the phonon frequencies at short times for coherent states and low temperature thermal distribution. In the former case, if the phonon energies are much larger than spin-phonon coupling or bath spins are fully polarized, decoherence time becomes independent of the initial phonon state. For the thermal state case, phonons play more important role in decoherence with increasing temperature. Possible effects of the temperature on spin bath contribution to decoherence is discussed. Then, the effect of entangled environment on decoherence is analyzed. Entanglement within environment is shown to reduce the decoherence of central spin. Also, the entanglement dynamics of the central bipartite spin system is studied. Classification of the Bell states is examined for common spin bath, and separate spin baths. Last part of the thesis is the analysis of dephasing in entangled qutrits (three level quantum systems) under the classical noise, and quantum decoherence. Density matrix formalism is shown to give equivalent results for both cases. For common and separate baths, robust and fragile Bell-like qutrit states were determined, and Horodecki's bound entangled state is shown to be more robust to decoherence in the latter case.
Interacting central spin systems, in which a central spin is coupled to a strongly correlated spin bath with intrabath interaction, consist of an important class of spin systems beyond the usual Gaudin magnet. These systems are relevant to several realistic setups and serve as an interesting platform to study interaction controlled decoherence and frustration induced instability of magnetic order. Using an equations-of-motion method based on analytical representations of spin-operator matrix elements in the XX chain, we obtain exact long-time dynamics of a generalized Heisenberg star consisting of a spin-SSS central spin and an inhomogeneously coupled XXZ chain of $N\ensuremath{\le}16$ bath spins. In contrast to previous studies where the central spin dynamics is mainly concerned, we focus on the influence of the central spin on the dynamics of magnetic orders within the spin bath. By preparing the XXZ bath in a N\'eel state, we find that in the gapless phase of the bath even weak system-bath coupling could lead to nearly perfect relaxation of the antiferromagnetic order. In the gapped phase, the staggered magnetization decays rapidly and approaches a steady value that increases with increasing anisotropy parameter. These findings suggest the possibility of controlling internal dynamics of strongly correlated many-spin systems by certain coupled auxiliary systems of even few degrees of freedom. We also study the dynamics of the R\'enyi entanglement entropy of the central spin when the bath is prepared in the ground state. Both the overall profile and initial growth rate of the R\'enyi entropy are found to exhibit minima at the critical point of the XXZ bath.