光学双稳系统的记忆,涨落与随机力

Memory, Fluctuations and Stochastic Forces of OpticalBitable Systems

本文的研究结果表明，作为记忆元件的双稳系统应在远离平衡统计分布的准平衡分布状态下运行。Ｂｏｎｉｆａｃｉｏ与Ｌｕｇｉａｔｏ等提出关着重讨论过的所谓‘反常’涨落，其实是平衡分布的双稳系统所有固有，这也是在平衡分布下它完全失去记忆功能的一种反映。在双稳系统中，随机力既驱使涨落增长，又通过非线性项对涨落起镇定作用。

The paper makes a discussion on fluctuations, statistical distribution andstochastic forces of optical bistable systems. When the bistable system is underthe equilibrium distribution, the probability of being situated in the low or highbranch will be independent of initial conditions(past history)and consequently, itsmemory function is lost in principle. We think that the bistable system as a memoryelement, in fact, operates in the state of quasi-equilibrium distribution, so that itis possible to avoid the so called ` anomalous fluctuation , whose peak isat the equipotential point(Maxwell rule) and which, in a sense, is inherent in thebistability. In nonlinear systems, including the bistable one, the stochastic force(noise) possesses dual nature. it drives fluctuations to be increased and on the otherhand, the fluctuations arc stabilized by the stochatics force via relevant nonlinearterms.Therefore, as the system approachs to a critical point , fluctuations have alimit value to be finite other than infinite in the case of that the Gaussian (linear)approximation is taken for the bimodal distribution function. The limit value ofthe fluctuation for unstable critical point(up-or down-threshold) is greater than forstable one.