Fluctuation relations for heat exchange in the generalized Gibbs ensemble

In this work, we investigate the heat exchange between two quantum systems whose initial equilibrium states are described by the generalized Gibbs ensemble. First, we generalize the fluctuation relations for heat exchange discovered by Jarzynski and Wojcik to quantum systems prepared in the equilibrium states described by the generalized Gibbs ensemble at various generalized temperatures. Secondly, we extend the connections between heat exchange and the Renyi divergences to quantum systems under generic initial conditions. These relations are applicable for quantum systems with conserved quantities and universally valid for quantum systems in the integrable and chaotic regimes.

Symmetry properties of fluctuations in an actively driven rotor

We investigate rotational dynamics of an actively driven rotor through experiments and numerical simulations. While probability density distributions of rotor angular velocity are strongly non-Gaussian, relative probabilities of observing rotation in opposite directions are shown to be linearly related to the angular velocity magnitude. We construct a stochastic model to describe transitions between different states from rotor angular velocity data and use the stochastic model to show that symmetry properties in probability density distributions are related to the detailed fluctuation relation(FR) of entropy productions.

Low frequency noise in asymmetric double barrier magnetic tunnel junctions with a top thin MgO layer

Low frequency noise has been investigated at room temperature for asymmetric double barrier magnetic tunnel junctions（DBMTJs）, where the coupling between the top and middle CoFeB layers is antiferromagnetic with a 0.8-nm thin top Mg O barrier of the CoFeB/MgO/CoFe/CoFeB/MgO/CoFe B DBMTJ. At enough large bias, 1/f noise dominates the voltage noise power spectra in the low frequency region, and is conventionally characterized by the Hooge parameter αmag.With increasing external field, the top and bottom ferromagnetic layers are aligned by the field, and then the middle free layer rotates from antiparallel state（antiferromagnetic coupling between top and middle ferromagnetic layers） to parallel state. In this rotation process αmag and magnetoresistance-sensitivity-product show a linear dependence, consistent with the fluctuation dissipation relation. With the magnetic field applied at different angles（θ） to the easy axis of the free layer,the linear dependence persists while the intercept of the linear fit satisfies a cos（θ） dependence, similar to that for the magnetoresistance, suggesting intrinsic relation between magnetic losses and magnetoresistance.

Effects of hydrological and climatic variables on cyanobacterial blooms in four large shallow lakes fed by the Yangtze River

Shallow lakes,one of the most widespread water bodies in the world,are easily shifted to a new trophic state due to external interferences.Shifting hydrologic conditions and climate change can cause cyanobacterial harmful algal blooms(CyanoHABs)in shallow lakes,which pose serious threats to ecological integrity and human health.This study analyzed the effects of hydrologic and meteorological variables on cyanobacterial blooms in Yangtze-connected lakes(Lake Dongting and Poyang)and isolated lakes(Lake Chao and Tai).The results show that(i)chlorophyll-a(Chl-a)concentration tends to decrease exponentially with increasing relative lake level fluctuations(RLLF)and precipitation,but to increase linearly with increasing wind speed and air temperature;(ii)Chl-a concentrations in lakes were significantly higher when RLLF<100,precipitation<2.6 mm,wind speed>2.6 ms^(-1),or air temperature>17.8℃;(iii)the Chl-a concentration of Yangtze-isolated lakes was more significantly affected by water level amplitude,precipitation,wind speed and air temperature than the Yangtze-connected lakes;(iv)the RLLF and the ratio of wind speed to mean water depth could be innovative coupling factors to examine variation characteristics of Chl-a in shallow lakes with greater correlation than single factors.