High precision calibration of optical lattice depth based on multiple pulses Kapitza-Dirac diffraction

The precise calibration of optical lattice depth is an important step in the experiments of ultracold atoms in optical lattices. The Raman-Nath di raction method, as the most commonly used method of calibrating optical lattice depth, has a limited range of validity and the calibration accuracy is not high enough. Based on multiple pulses Kapitza-Dirac di raction, we propose and demonstrate a new calibration method by measuring the fully transfer fidelity of the first di raction order. The high sensitivity of the transfer fidelity to the lattice depth ensures the highly precision calibration of the optical lattice depth. For each lattice depth measured, the calibration uncertainty is further reduced to less than 0.6% by applying the Back-Propagation Neural Network Algorithm. The accuracy of this method is almost one order of magnitude higher than that of the Raman-Nath di raction method, and it has a wide range of validity applicable to both shallow lattices and deep lattices.