Nonlinear Relaxation Phenomena in Metastable Condensed Matter Systems
Nonlinear relaxation phenomena in three different systems of condensed matter are investigated. (i) First, the phase dynamics in Josephson junctions is analyzed. Specifically, a superconductor-graphene-superconductor (SGS) system exhibits quantum metastable states, and the average escape time from t...
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MDPI AG
2016-12-01
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| author | Bernardo Spagnolo Claudio Guarcello Luca Magazzù Angelo Carollo Dominique Persano Adorno Davide Valenti |
| author_facet | Bernardo Spagnolo Claudio Guarcello Luca Magazzù Angelo Carollo Dominique Persano Adorno Davide Valenti |
| author_sort | Bernardo Spagnolo |
| collection | DOAJ |
| description | Nonlinear relaxation phenomena in three different systems of condensed matter are investigated. (i) First, the phase dynamics in Josephson junctions is analyzed. Specifically, a superconductor-graphene-superconductor (SGS) system exhibits quantum metastable states, and the average escape time from these metastable states in the presence of Gaussian and correlated fluctuations is calculated, accounting for variations in the the noise source intensity and the bias frequency. Moreover, the transient dynamics of a long-overlap Josephson junction (JJ) subject to thermal fluctuations and non-Gaussian noise sources is investigated. Noise induced phenomena are observed, such as the noise enhanced stability and the stochastic resonant activation. (ii) Second, the electron spin relaxation process in a n-type GaAs bulk driven by a fluctuating electric field is investigated. In particular, by using a Monte Carlo approach, we study the influence of a random telegraph noise on the spin polarized transport. Our findings show the possibility to raise the spin relaxation length by increasing the amplitude of the external fluctuations. Moreover, we find that, crucially, depending on the value of the external field strength, the electron spin depolarization length versus the noise correlation time increases up to a plateau. (iii) Finally, the stabilization of quantum metastable states by dissipation is presented. Normally, quantum fluctuations enhance the escape from metastable states in the presence of dissipation. We show that dissipation can enhance the stability of a quantum metastable system, consisting of a particle moving in a strongly asymmetric double well potential, interacting with a thermal bath. We find that the escape time from the metastable region has a nonmonotonic behavior versus the system- bath coupling and the temperature, producing a stabilizing effect. |
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| last_indexed | 2024-12-10T06:53:22Z |
| publishDate | 2016-12-01 |
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| series | Entropy |
| spelling | doaj.art-f6f8211ebc964dd19f18e6fe52ce52712022-12-22T01:58:30ZengMDPI AGEntropy1099-43002016-12-011912010.3390/e19010020e19010020Nonlinear Relaxation Phenomena in Metastable Condensed Matter SystemsBernardo Spagnolo0Claudio Guarcello1Luca Magazzù2Angelo Carollo3Dominique Persano Adorno4Davide Valenti5Dipartimento di Fisica e Chimica, Interdisciplinary Theoretical Physics Group, Università di Palermo and CNISM, Unità di Palermo, Viale delle Scienze, Edificio 18, I-90128 Palermo, ItalySPIN-CNR, Via Dodecaneso 33, I-16146 Genova, ItalyInstitute of Physics, University of Augsburg, Universitätsstrasse 1, D-86135 Augsburg, GermanyDipartimento di Fisica e Chimica, Interdisciplinary Theoretical Physics Group, Università di Palermo and CNISM, Unità di Palermo, Viale delle Scienze, Edificio 18, I-90128 Palermo, ItalyDipartimento di Fisica e Chimica, Interdisciplinary Theoretical Physics Group, Università di Palermo and CNISM, Unità di Palermo, Viale delle Scienze, Edificio 18, I-90128 Palermo, ItalyDipartimento di Fisica e Chimica, Interdisciplinary Theoretical Physics Group, Università di Palermo and CNISM, Unità di Palermo, Viale delle Scienze, Edificio 18, I-90128 Palermo, ItalyNonlinear relaxation phenomena in three different systems of condensed matter are investigated. (i) First, the phase dynamics in Josephson junctions is analyzed. Specifically, a superconductor-graphene-superconductor (SGS) system exhibits quantum metastable states, and the average escape time from these metastable states in the presence of Gaussian and correlated fluctuations is calculated, accounting for variations in the the noise source intensity and the bias frequency. Moreover, the transient dynamics of a long-overlap Josephson junction (JJ) subject to thermal fluctuations and non-Gaussian noise sources is investigated. Noise induced phenomena are observed, such as the noise enhanced stability and the stochastic resonant activation. (ii) Second, the electron spin relaxation process in a n-type GaAs bulk driven by a fluctuating electric field is investigated. In particular, by using a Monte Carlo approach, we study the influence of a random telegraph noise on the spin polarized transport. Our findings show the possibility to raise the spin relaxation length by increasing the amplitude of the external fluctuations. Moreover, we find that, crucially, depending on the value of the external field strength, the electron spin depolarization length versus the noise correlation time increases up to a plateau. (iii) Finally, the stabilization of quantum metastable states by dissipation is presented. Normally, quantum fluctuations enhance the escape from metastable states in the presence of dissipation. We show that dissipation can enhance the stability of a quantum metastable system, consisting of a particle moving in a strongly asymmetric double well potential, interacting with a thermal bath. We find that the escape time from the metastable region has a nonmonotonic behavior versus the system- bath coupling and the temperature, producing a stabilizing effect.http://www.mdpi.com/1099-4300/19/1/20metastabilitynonequilibrium statistical mechanics and nonlinear relaxation timenoise enhanced stabilityJosephson junctionspin polarized transport in semiconductorsopen quantum systemsquantum noise enhanced stability |
| spellingShingle | Bernardo Spagnolo Claudio Guarcello Luca Magazzù Angelo Carollo Dominique Persano Adorno Davide Valenti Nonlinear Relaxation Phenomena in Metastable Condensed Matter Systems Entropy metastability nonequilibrium statistical mechanics and nonlinear relaxation time noise enhanced stability Josephson junction spin polarized transport in semiconductors open quantum systems quantum noise enhanced stability |
| title | Nonlinear Relaxation Phenomena in Metastable Condensed Matter Systems |
| title_full | Nonlinear Relaxation Phenomena in Metastable Condensed Matter Systems |
| title_fullStr | Nonlinear Relaxation Phenomena in Metastable Condensed Matter Systems |
| title_full_unstemmed | Nonlinear Relaxation Phenomena in Metastable Condensed Matter Systems |
| title_short | Nonlinear Relaxation Phenomena in Metastable Condensed Matter Systems |
| title_sort | nonlinear relaxation phenomena in metastable condensed matter systems |
| topic | metastability nonequilibrium statistical mechanics and nonlinear relaxation time noise enhanced stability Josephson junction spin polarized transport in semiconductors open quantum systems quantum noise enhanced stability |
| url | http://www.mdpi.com/1099-4300/19/1/20 |
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