Atom–light interface is at the core of quantum metrology and quantum information science.Associated noises during interaction processes are always inevitable and adverse.In this paper,we perform the stimulated Raman ...Atom–light interface is at the core of quantum metrology and quantum information science.Associated noises during interaction processes are always inevitable and adverse.In this paper,we perform the stimulated Raman scattering(SRS)in a hot Rb 87 vapor cell and demonstrate the reduction of related noises originated from mode mismatch via optimizing the temporal waveform of the input seed.By using the seed with the optimized mode,the intensity fluctuation of the signal field generated in atom–light interaction is decreased by 4.3 dB.Furthermore,the fluctuation of the intensity difference between the signal and atomic spin wave is reduced by 3.1 dB.Such a temporal mode-cleaning method can be applied to improve the precision of atom interferometry using SRS and should be helpful for quantum information processing based on an atom–light correlated system.展开更多
Quantum non-demolition(QND) measurement is an important tool in the fields of quantum information processing and quantum optics. The atom-light hybrid interferometer is of great interest due to its combination of an a...Quantum non-demolition(QND) measurement is an important tool in the fields of quantum information processing and quantum optics. The atom-light hybrid interferometer is of great interest due to its combination of an atomic spin wave and an optical wave, which can be utilized for photon number QND measurement via the AC-Stark effect. In this paper, we present an SU(1,1)-SU(2)-concatenated atom-light hybrid interferometer, and theoretically study QND measurement of the photon number. Compared to the traditional SU(2) interferometer,the signal-to-noise ratio in a balanced case is improved by a gain factor of the nonlinear Raman process(NRP)in this proposed interferometer. Furthermore, the condition of high-quality QND measurement is analyzed. In the presence of losses, the measurement quality is reduced. We can adjust the gain parameter of the NRP in the readout stage to reduce the impact due to losses. Moreover, this scheme is a multiarm interferometer, which has the potential of multiparameter estimation with many important applications in the detection of vector fields,quantum imaging, and so on.展开更多
The coarsening kinetics of a two-phase mixture with a large diffusional mobility disparity between the two phases is studied using a variable-mobility Cahn Hilliard equation.The semi-implicit spectral numerical techni...The coarsening kinetics of a two-phase mixture with a large diffusional mobility disparity between the two phases is studied using a variable-mobility Cahn Hilliard equation.The semi-implicit spectral numerical technique was employed,and a number of interpolation functions are considered for describing the change in diffusion mobility across the interface boundary from one phase to another.The coarsening rate of domain size was measured using both structure and pair correlation functions as well as the direct computation of particle sizes in real space for the case that the coarsening phase consists of dispersed particles.We discovered that the average size(R)versus time(t)follows the R^(10/3)∝t law,in contrast to the conventional LSW theory,R^(3)∝t,and the interface-diffusion dominated two-phase coarsening,R^(4)∝t.展开更多
In recent years,Fourier spectral methods have emerged as competitive numerical methods for large-scale phase field simulations of microstructures in computational materials sciences.To further improve their effectiven...In recent years,Fourier spectral methods have emerged as competitive numerical methods for large-scale phase field simulations of microstructures in computational materials sciences.To further improve their effectiveness,we recently developed a new adaptive Fourier-spectral semi-implicit method(AFSIM)for solving the phase field equation by combining an adaptive moving mesh method and the semi-implicit Fourier spectral algorithm.In this paper,we present the application of AFSIM to the Cahn-Hilliard equation with inhomogeneous,anisotropic elasticity.Numerical implementations and test examples in both two and three dimensions are considered with a particular illustration using the well-studied example of mis-fitting particles in a solid as they approach to their equilibrium shapes.It is shown that significant savings in memory and computational time is achieved while accurate solutions are preserved.展开更多
基金National Key Research and Development Program of China(2016YFA0302001)National Natural Science Foundation of China(11874152,11974111,11604069,11654005,91536114)+2 种基金Natural Science Foundation of Shanghai(17ZR1442800)Fundamental Research Funds for the Central UniversitiesShanghai Municipal Science and Technology Major Project(2019SHZDZX01).
文摘Atom–light interface is at the core of quantum metrology and quantum information science.Associated noises during interaction processes are always inevitable and adverse.In this paper,we perform the stimulated Raman scattering(SRS)in a hot Rb 87 vapor cell and demonstrate the reduction of related noises originated from mode mismatch via optimizing the temporal waveform of the input seed.By using the seed with the optimized mode,the intensity fluctuation of the signal field generated in atom–light interaction is decreased by 4.3 dB.Furthermore,the fluctuation of the intensity difference between the signal and atomic spin wave is reduced by 3.1 dB.Such a temporal mode-cleaning method can be applied to improve the precision of atom interferometry using SRS and should be helpful for quantum information processing based on an atom–light correlated system.
基金National Key Research and Development Program of China(2016YFA0302001)National Natural Science Foundation of China(11974111,11874152,91536114,11574086,11974116,11654005)+4 种基金Shanghai Rising-Star Program(16QA1401600)Innovation Program of Shanghai Municipal Education Commission(202101070008E00099)Shanghai Talent ProgramChinese National Youth Talent Support ProgramFundamental Research Funds for the Central Universities。
文摘Quantum non-demolition(QND) measurement is an important tool in the fields of quantum information processing and quantum optics. The atom-light hybrid interferometer is of great interest due to its combination of an atomic spin wave and an optical wave, which can be utilized for photon number QND measurement via the AC-Stark effect. In this paper, we present an SU(1,1)-SU(2)-concatenated atom-light hybrid interferometer, and theoretically study QND measurement of the photon number. Compared to the traditional SU(2) interferometer,the signal-to-noise ratio in a balanced case is improved by a gain factor of the nonlinear Raman process(NRP)in this proposed interferometer. Furthermore, the condition of high-quality QND measurement is analyzed. In the presence of losses, the measurement quality is reduced. We can adjust the gain parameter of the NRP in the readout stage to reduce the impact due to losses. Moreover, this scheme is a multiarm interferometer, which has the potential of multiparameter estimation with many important applications in the detection of vector fields,quantum imaging, and so on.
基金the financial supports from the National Science Foundation under the grant number DMR-0710483(Chen)NSF-DMS 0712744(Du)+1 种基金DMR-0510180(Liu)DMR-0710484(K.G.Wang).
文摘The coarsening kinetics of a two-phase mixture with a large diffusional mobility disparity between the two phases is studied using a variable-mobility Cahn Hilliard equation.The semi-implicit spectral numerical technique was employed,and a number of interpolation functions are considered for describing the change in diffusion mobility across the interface boundary from one phase to another.The coarsening rate of domain size was measured using both structure and pair correlation functions as well as the direct computation of particle sizes in real space for the case that the coarsening phase consists of dispersed particles.We discovered that the average size(R)versus time(t)follows the R^(10/3)∝t law,in contrast to the conventional LSW theory,R^(3)∝t,and the interface-diffusion dominated two-phase coarsening,R^(4)∝t.
基金This work has been supported by the National Science Foundation Information Technol-ogy Research Project(NSF-ITR)through Grant DMR-0205232The work of Qiang Du is also supported by NSF-DMS 0712744.
文摘In recent years,Fourier spectral methods have emerged as competitive numerical methods for large-scale phase field simulations of microstructures in computational materials sciences.To further improve their effectiveness,we recently developed a new adaptive Fourier-spectral semi-implicit method(AFSIM)for solving the phase field equation by combining an adaptive moving mesh method and the semi-implicit Fourier spectral algorithm.In this paper,we present the application of AFSIM to the Cahn-Hilliard equation with inhomogeneous,anisotropic elasticity.Numerical implementations and test examples in both two and three dimensions are considered with a particular illustration using the well-studied example of mis-fitting particles in a solid as they approach to their equilibrium shapes.It is shown that significant savings in memory and computational time is achieved while accurate solutions are preserved.
