6 research outputs found
OTOC, complexity and entropy in bi-partite systems
There is a remarkable interest in the study of Out-of-time ordered
correlators (OTOCs) that goes from many body theory and high energy physics to
quantum chaos. In this latter case there is a special focus on the comparison
with the traditional measures of quantum complexity such as the spectral
statistics, for example. The exponential growth has been verified for many
paradigmatic maps and systems. But less is known for multi-partite cases. On
the other hand the recently introduced Wigner separability entropy (WSE) and
its classical counterpart (CSE) provide with a complexity measure that treats
equally quantum and classical distributions in phase space. We have compared
the behavior of these measures in a system consisting of two coupled and
perturbed cat maps with different dynamics: double hyperbolic (HH), double
elliptic (EE) and mixed (HE). In all cases, we have found that the OTOCs and
the WSE have essentially the same behavior, providing with a complete
characterization in generic bi-partite systems and at the same time revealing
them as very good measures of quantum complexity for phase space distributions.
Moreover, we establish a relation between both quantities by means of a
recently proven theorem linking the second Renyi entropy and OTOCs.Comment: 6 pages, 5 figure
Quantum and classical complexity in coupled maps
We study a generic and paradigmatic two-degrees-of-freedom system consisting of two coupled perturbed cat maps with different types of dynamics. The Wigner separability entropy (WSE)—equivalent to the operator space entanglement entropy—and the classical separability entropy (CSE) are used as measures of complexity. For the case where both degrees of freedom are hyperbolic, the maps are classically ergodic and the WSE and the CSE behave similarly, growing to higher values than in the doubly elliptic case. However, when one map is elliptic and the other hyperbolic, the WSE reaches the same asymptotic value than that of the doubly hyperbolic case but at a much slower rate. The CSE only follows the WSE for a few map steps, revealing that classical dynamical features are not enough to explain complexity growth.Fil: Bergamasco, Pablo D.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Carlo, Gabriel Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Rivas, Alejandro Mariano Fidel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentin
Relevant OTOC operators: footprints of the classical dynamics
The out-of-time order correlator (OTOC) has recently become relevant in
different areas where it has been linked to scrambling of quantum information
and entanglement. It has also been proposed as a good indicator of quantum
complexity. In this sense, the OTOC-RE theorem relates the OTOCs summed over a
complete base of operators to the second Renyi entropy. Here we have studied
the OTOC-RE correspondence on physically meaningful bases like the ones
constructed with the Pauli, reflection, and translation operators. The
evolution is given by a paradigmatic bi-partite system consisting of two
perturbed and coupled Arnold cat maps with different dynamics. We show that the
sum over a small set of relevant operators, is enough in order to obtain a very
good approximation for the entropy and hence to reveal the character of the
dynamics, up to a time t 0 . In turn, this provides with an alternative natural
indicator of complexity, i.e. the scaling of the number of relevant operators
with time. When represented in phase space, each one of these sets reveals the
classical dynamical footprints with different depth according to the chosen
base.Comment: 8 pages, 10 figure
Quantum Lyapunov exponent in dissipative systems
The out-of-time order correlator (OTOC) has been widely studied in closed
quantum systems. However, there are very few studies for open systems and they
are mainly focused on isolating the effects of scrambling from those of
decoherence. Adopting a different point of view, we study the interplay between
these two processes. This proves crucial in order to explain the OTOC behavior
when a phase space contracting dissipation is present, ubiquitous not only in
real life quantum devices but in the dynamical systems area. The OTOC decay
rate is closely related to the classical Lyapunov exponent -- with some
differences -- and more sensitive in order to distinguish the chaotic from the
regular behavior than other measures. On the other hand, it reveals as a
generally simple function of the longest lived eigenvalues of the quantum
evolution operator. We find no simple connection with the Ruelle-Pollicott
resonances, but by adding Gaussian noise of size to the
classical system we recover the OTOC decay rate, being this a consequence of
the correspondence principle put forward in [Physical Review Letters 108 210605
(2012) and Physical Review E 99 042214 (2019)]Comment: 5 pages, 7 figure
Ten golden rules for optimal antibiotic use in hospital settings: the WARNING call to action
Antibiotics are recognized widely for their benefits when used appropriately. However, they are often used inappropriately despite the importance of responsible use within good clinical practice. Effective antibiotic treatment is an essential component of universal healthcare, and it is a global responsibility to ensure appropriate use. Currently, pharmaceutical companies have little incentive to develop new antibiotics due to scientific, regulatory, and financial barriers, further emphasizing the importance of appropriate antibiotic use. To address this issue, the Global Alliance for Infections in Surgery established an international multidisciplinary task force of 295 experts from 115 countries with different backgrounds. The task force developed a position statement called WARNING (Worldwide Antimicrobial Resistance National/International Network Group) aimed at raising awareness of antimicrobial resistance and improving antibiotic prescribing practices worldwide. The statement outlined is 10 axioms, or “golden rules,” for the appropriate use of antibiotics that all healthcare workers should consistently adhere in clinical practice
Ten golden rules for optimal antibiotic use in hospital settings : the WARNING call to action
Abstract: Antibiotics are recognized widely for their benefits when used appropriately. However, they are often used inappropriately despite the importance of responsible use within good clinical practice. Effective antibiotic treatment is an essential component of universal healthcare, and it is a global responsibility to ensure appropriate use. Currently, pharmaceutical companies have little incentive to develop new antibiotics due to scientific, regulatory, and financial barriers, further emphasizing the importance of appropriate antibiotic use. To address this issue, the Global Alliance for Infections in Surgery established an international multidisciplinary task force of 295 experts from 115 countries with different backgrounds. The task force developed a position statement called WARNING (Worldwide Antimicrobial Resistance National/International Network Group) aimed at raising awareness of antimicrobial resistance and improving antibiotic prescribing practices worldwide. The statement outlined is 10 axioms, or "golden rules," for the appropriate use of antibiotics that all healthcare workers should consistently adhere in clinical practice