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Atomic nonlinear interferometry has wide applications in quantum metrology and quantum information science. Here we propose a nonlinear time-reversal interferometry scheme with high robustness and metrological gain based on the spin squeezing generated by arbitrary quadratic collective-spin interaction, which could be described by the Lipkin–Meshkov–Glick (LMG) model. We optimize the squeezing process, encoding process, and anti-squeezing process, finding that the two particular cases of the LMG model, one-axis twisting and two-axis twisting outperform in robustness and precision, respectively. Moreover, we propose a Floquet driving method to realize equivalent time reverse in the atomic system, which leads to high performance in precision, robustness, and operability. Our study sets a benchmark for achieving high precision and high robustness in atomic nonlinear interferometry. [ABSTRACT FROM AUTHOR]

We identify a comprehensive list of thirty-eight characteristics for predicting cross-sectional FX options returns. We find that three factors—long-term straddle momentum, implied volatility, and illiquidity—can generate economically and statistically significant risk premia not explained by other return predictors. Meanwhile, the predictability of the other characteristics becomes insignificant after accounting for the FX option three-factor model. The significance of the three factors is confirmed through a series of robustness tests covering different data sources, alternative options strategies, diversification effects, bootstrapping, and omitting crisis years. [ABSTRACT FROM AUTHOR]

Robot calibration has been demonstrated to be a useful method to decrease the absolute positioning errors of a robot. Compared to the traditional calibration methods which require expensive external measurement devices, this paper proposes a stereo vision based self-calibration procedure which only needs a stereo camera mounted to a fixed location and a planar marker attached to the robot end-effector. The procedure consists of three consecutive steps: the automatic generation of target configurations and trajectories based on the nominal geometric models of the robot; a camera and obstacles, marker poses estimated by the two stage estimation algorithm; and the kinematic parameters identification based on a local product of exponential (local POE) formulized error model. The advantage of this self-calibration method is that the whole robot camera system can be calibrated without any manual intervention, which enables robot calibration to be completely online and suitable for the fast programming of the robot and computer vision combined work cell. A set of simulations and experiments on a UR5 robot demonstrate the convenience, efficiency and robustness of the proposed calibration procedure. [ABSTRACT FROM AUTHOR]

The Greenberger-Horne-Zeilinger (GHZ) state is a key resource for quantum information processing and quantum metrology. The atomic GHZ state can be generated by one-axis twisting (OAT) interaction H_{OAT}=χJ_{z}^{2} with χ the interaction strength, but it requires a long evolution time χt=π/2 and is thus seriously influenced by decoherence and losses. Here we propose a three-body collective-spin XYZ model which creates a GHZ-like state in a very short timescale χt∼lnN/N for N particles. We show that this model can be effectively produced by applying Floquet driving to an original OAT Hamiltonian. Compared with the ideal GHZ state, the GHZ-like state generated using our model can maintain similar metrological properties reaching the Heisenberg-limited scaling, and it shows better robustness to decoherence and particle losses. This Letter opens the avenue for generating GHZ-like states with a large particle number, which holds great potential for the study of macroscopic quantum effects and for applications in quantum metrology and quantum information.