We investigate the optimal control of open quantum systems, in particular, the mutual influence of driving and dissipation. A stochastic approach to open-system control is developed, using a generalized version of Krotov's iterative algorithm, with no need for Markovian or rotating-wave approximations. The application to a harmonic degree of freedom reveals cooperative effects of driving and dissipation that a standard Markovian treatment cannot capture. Remarkably, control can modify the open-system dynamics to the point where the entropy change turns negative, thus achieving cooling of translational motion without any reliance on internal degrees of freedom.
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Entropy (Basel)
January 2025
Chula Intelligent and Complex Systems Lab, Department of Physics, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
Quantum reservoir computing (QRC) has emerged as a promising paradigm for harnessing near-term quantum devices to tackle temporal machine learning tasks. Yet, identifying the mechanisms that underlie enhanced performance remains challenging, particularly in many-body open systems where nonlinear interactions and dissipation intertwine in complex ways. Here, we investigate a minimal model of a driven-dissipative quantum reservoir described by two coupled Kerr-nonlinear oscillators, an experimentally realizable platform that features controllable coupling, intrinsic nonlinearity, and tunable photon loss.
View Article and Find Full Text PDFClocks Sleep
January 2025
Circadian Physics Group, School of Physics, University of Sydney, Sydney, NSW 2006, Australia.
Fixed sleep schedules with an 8 h time in bed (TIB) are used to ensure participants are well-rested before laboratory studies. However, such schedules may lead to cumulative excess wakefulness in young individuals. Effects on older individuals are unknown.
View Article and Find Full Text PDFNature
January 2025
Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
The integrated frequency comb generator based on Kerr parametric oscillation has led to chip-scale, gigahertz-spaced combs with new applications spanning hyperscale telecommunications, low-noise microwave synthesis, light detection and ranging, and astrophysical spectrometer calibration. Recent progress in lithium niobate (LiNbO) photonic integrated circuits (PICs) has resulted in chip-scale, electro-optic (EO) frequency combs, offering precise comb-line positioning and simple operation without relying on the formation of dissipative Kerr solitons. However, current integrated EO combs face limited spectral coverage due to the large microwave power required to drive the non-resonant capacitive electrodes and the strong intrinsic birefringence of LiNbO.
View Article and Find Full Text PDFSci Total Environ
January 2025
Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Avenida Antônio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais 31270-901, Brazil. Electronic address:
The initial performance of seedlings of tree species from different functional groups, regarding the growth-defense tradeoff, might determine its long-term success during the rehabilitation of mining areas. We monitored the field performance of six native tree species of the Atlantic Forest in the Fundão dam tailing that has been under rehabilitation for 35 months. Additionally, we explored the morphophysiological traits driving the superior performance of three species.
View Article and Find Full Text PDFJ Phys Condens Matter
January 2025
Mechanical Engineering, Virginia Tech, 635 Prices Fork Road, Blacksburg, Virginia, 24061-0131, UNITED STATES.
Magnetorheological elastomers (MREs) are soft magnetic composites that achieve tunable changes in stiffness and energy response in the presence of a magnetic field. Rigid particle composite (RC) MREs have been studied for decades for their potential applications to automotive dampers and robotic systems. Recently, magnetic fluid composite (FC) MREs have been developed which utilize magnetic fluids as inclusions to elastomers.
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