Search results for "memory effect"
showing 6 items of 6 documents
Temperature effects on quantum non-Markovianity via collision models
2018
Quantum non-Markovianity represents memory during the system dynamics, which is typically weakened by the temperature. We here study the effects of environmental temperature on the non-Markovianity of an open quantum system by virtue of collision models. The environment is simulated by a chain of ancillary qubits that are prepared in thermal states with a finite temperature $T$. Two distinct non-Markovian mechanisms are considered via two types of collision models, one where the system $S$ consecutively interacts with the ancillas and a second where $S$ collides only with an intermediate system $S'$ which in turn interacts with the ancillas. We show that in both models the relation between …
'VA HAVER-HI UN TEMPS NO TAN LLUNYÀ...' RELATS I ESTÈTIQUES DE LA MEMÒRIA I IDEOLOGIA DE LA RECONCILIACIÓ A ESPANYA
2011
En la última década se han consolidado en España nuevos estilos culturales con los que representar el pasado reciente, en estrecha relación con la emergencia de los debates en torno a la llamada memoria histórica y con el desarrollo contemporáneo de las industrias culturales. Esos estilos han llegado a estandarizar una serie de procedimientos de composición y efectos textuales que permiten que el público los identifique con las estéticas de la memoria. El testimonio, como forma paraliteraria y discurso cívico, ha alcanzado un lugar de excepción en esa estandarización de las estéticas de memoria, pero su uso mecanizado ha privilegiado su rentabilidad dramática sobre su potencial crítico.
Fluctuation theorems for non-Markovian quantum processes
2013
Exploiting previous results on Markovian dynamics and fluctuation theorems, we study the consequences of memory effects on single realizations of nonequilibrium processes within an open system approach. The entropy production along single trajectories for forward and backward processes is obtained with the help of a recently proposed classical-like non-Markovian stochastic unravelling, which is demonstrated to lead to a correction of the standard entropic fluctuation theorem. This correction is interpreted as resulting from the interplay between the information extracted from the system through measurements and the flow of information from the environment to the open system: Due to memory e…
Memory Effects in High-Dimensional Systems Faithfully Identified by Hilbert–Schmidt Speed-Based Witness
2022
A witness of non-Markovianity based on the Hilbert–Schmidt speed (HSS), a special type of quantum statistical speed, has been recently introduced for low-dimensional quantum systems. Such a non-Markovianity witness is particularly useful, being easily computable since no diagonalization of the system density matrix is required. We investigate the sensitivity of this HSS-based witness to detect non-Markovianity in various high-dimensional and multipartite open quantum systems with finite Hilbert spaces. We find that the time behaviors of the HSS-based witness are always in agreement with those of quantum negativity or quantum correlation measure. These results show that the HSS-based witness…
Nanocrystal MOS memories obtained by LPCVD deposition of Si nanograins
2001
We have realized silicon quantum dots embedded in SiO2 which act as nano-floating gates of MOS memories. The dots with nanometer sizes have been deposited by LPCVD on a 3nm tunnel oxide. Two processes at a fixed pressure have been explored by varying the temperature. SiH4 with a N2 carrier gas have been used in the former case, SiH4 and H2 have been used in the latter. In both cases a nanocrystalline silicon layer is obtained, with nanocrystals a density higher than 1011 cm-2. The process with H2 carrier gas is more controllable and leads to the formation of nanocrystals with a more regular shape. In both cases the density of grains is able to originate detectable threshold shifts in the me…
Hidden entanglement, system-environment information flow and non-Markovianity
2014
It is known that entanglement dynamics of two noninteracting qubits, locally subjected to classical environments, may exhibit revivals. A simple explanation of this phenomenon may be provided by using the concept of hidden entanglement, which signals the presence of entanglement that may be recovered without the help of nonlocal operations. Here we discuss the link between hidden entanglement and the (non-Markovian) flow of classical information between the system and the environment.