Nonreciprocal strong mechanical squeezing based on the Sagnac effect and two-tone driving.

We propose a scheme for generating nonreciprocal strong mechanical squeezing by using two-tone lasers to drive a spinning optomechanical system. For given driving frequencies, strong mechanical squeezing of the breathing mode in the spinning resonator can be achieved in a chosen driving direction but not in the other. The nonreciprocity originates from the Sagnac effect caused by the resonator's spinning.

Real-Valued Direct Position Determination of Quasi-Stationary Signals for Nested Arrays: Khatri-Rao Subspace and Unitary Transformation.

The features of quasi-stationary signals (QSS) are considered to be in a direct position determination (DPD) framework, and a real-valued DPD algorithm of QSS for nested arrays is proposed. By stacking the vectorization form of the signal's covariance for different frames and further eliminating noise, a new noise-eliminated received signal matrix is obtained first. Then, the combination of the Khatri-Rao subspace method and subspace data fusion method was performed to form the cost function.