Effective dynamics and quantum state engineering by periodic kicks

We study the kick dynamics of periodically driven quantum systems,and provide a time-independent effective Hamiltonian with the analytical form to reasonably describe the effective dynamics in a long timescale.It is shown that the effective coupling strength can be much larger than the coupling strength of the original system in some parameter regions,which stems from the zero time duration of kicks.Furthermore,different regimes can be transformed from and to each other in the same three-level system by only modulating the period of periodic kicks.In particular,the population of excited states can be selectively suppressed in periodic kicks,benefiting from the large detuning regime of the original system.Finally,some applications and physical implementation of periodic kicks are demonstrated in quantum systems.These unique features would make periodic kicks become a powerful tool for quantum state engineering.

Seamless maps of major elements of the Moon:Results from high-resolution geostationary satellite

Major elements such as Fe,Ti,Mg,Al,Ca and Si play very important roles in understanding the origin and evolution of the Moon.Previous maps of these major elements derived from orbital data are based on mosaic images or low-resolution gamma-ray data.The hue variations and gaps among orbital boundaries in the mosaic images are not conducive to geological studies.This paper aims to produce seamless and homogenous distribution maps of major elements using the single-exposure image of the whole lunar disk obtained by China’s high-resolution geostationary satellite,Gaofen-4,with a spatial resolution of500 m.The elemental contents of soil samples returned by Apollo and Luna missions are regarded as ground truth,and are correlated with the reflectance of the sampling sites extracted from Gaofen-4 data.The final distribution maps of these major oxides are generated with the statistical regression model.With these products,the average contents and proportions of the major elements for maria and highlands were estimated and compared.The results showed that Si O2 and Ti O2 have the highest and lowest fractions in mare and highland areas,respectively.Moreover,the relative concentrations of these elements could serve as indicators of geologic processes,e.g.,the obviously asymmetric distributions of Al2 O3,Ca O and Si O2 around Tycho crater may suggest that Tycho crater was formed by an oblique impact from the southwest direction.

Optimized nonadiabatic holonomic quantum computation based on Förster resonance in Rydberg atoms

In this paper,we propose a scheme for implementing the nonadiabatic holonomic quantum computation(NHQC+)of two Rydberg atoms by using invariant-based reverse engineering(IBRE).The scheme is based on Förster resonance induced by strong dipole-dipole interaction between two Rydberg atoms,which provides a selective coupling mechanism to simply the dynamics of system.Moreover,for improving the fidelity of the scheme,the optimal control method is introduced to enhance the gate robustness against systematic errors.Numerical simulations show the scheme is robust against the random noise in control fields,the deviation of dipole-dipole interaction,the Förster defect,and the spontaneous emission of atoms.Therefore,the scheme may provide some useful perspectives for the realization of quantum computation with Rydberg atoms.

Detecting a single atom in a cavity using the χ^((2)) nonlinear medium

We propose a protocol for detecting a single atom in a cavity with the help of the χ^((2)) nonlinear medium.When the χ^((2)) nonlinear medium is driven by an external laser field,the cavity mode will be squeezed,and thus one can obtain an exponentially enhanced light-matter coupling.Such a strong coupling between the atom and the cavity field can significantly change the output photon flux,the quantum fluctuations,the quantum statistical property,and the photon number distributions of the cavity field.This provides practical strategies to determine the presence or absence of an atom in a cavity.The proposed protocol exhibits some advantages,such as controllable squeezing strength and exponential increase of atom-cavity coupling strength,which make the experimental phenomenon more obvious.We hope that this protocol can supplement the existing intracavity single-atom detection protocols and provide a promise for quantum sensing in different quantum systems.