分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Abstract The magneto-optical trap (MOT) is an essential tool for collecting and preparing cold atoms with a wide range of applications. We demonstrate a planar-integrated MOT by combining an optical grating chip with a magnetic coil chip. The flat grating chip simplifies the conventional six-beam configuration down to a single laser beam; the flat coil chip replaces the conventional anti-Helmholtz coils of a cylindrical geometry. We trap 10^{4} cold ^{87}\text{Rb} atoms in the planar-integrated MOT, at a point 3-9 mm above the chip surface. This novel configuration effectively reduces the volume, weight, and complexity of the MOT, bringing benefits to applications including gravimeter, clock and quantum memory devices.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Recently, the spectral manipulation of single photons has been achieved through spatial-temporal modulation of the optical refractive index. Here, we generalize this mechanism to massive particles, i.e. realizing the acceleration or deceleration of particles through the spatial-temporal modulation of potential induced by lasers. On a photonic integrated chip, we propose a MeV-magnitude acceleration by distributed modulation units driven by lasers. The mechanism could also be applied to atom trapping, which promises a millimeter-scale decelerator to trap atoms. The spatial-temporal modulation approach is universal and could be generalized to other systems, which may play a significant role in hybrid photonic chip and microscale particle manipulation.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Nonlinear optics processes lie at the heart of photonics and quantum optics for their indispensable role in light sources and information processing. During the past decades, the three- and four-wave mixing ($\chi^{(2)}$ and $\chi^{(3)}$) effects have been extensively studied, especially in the micro-/nano-structures by which the photon-photon interaction strength is greatly enhanced. So far, the high-order nonlinearity beyond the $\chi^{(3)}$ has rarely been studied in dielectric materials due to their weak intrinsic nonlinear susceptibility, even in high-quality microcavities. Here, an effective five-wave mixing process ($\chi^{(4)}$) is synthesized for the first time, by incorporating $\chi^{(2)}$ and $\chi^{(3)}$ processes in a single microcavity. The coherence of the synthetic $\chi^{(4)}$ is verified by generating time-energy entangled visible-telecom photon-pairs, which requires only one drive laser at the telecom waveband. The photon pair generation rate from the synthetic process shows an enhancement factor over $500$ times upon intrinsic five-wave mixing. Our work demonstrates a universal approach of nonlinear synthesis via photonic structure engineering at the mesoscopic scale rather than material engineering, and thus opens a new avenue for realizing high-order optical nonlinearities and exploring novel functional photonic devices.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: An on-chip multi-grating device is proposed to interface single-atoms and integrated photonic circuits, by guiding and focusing lasers to the area with ~10um above the chip for trapping, state manipulation, and readout of single Rubidium atoms. For the optical dipole trap, two 850 nm laser beams are diffracted and overlapped to form a lattice of single-atom dipole trap, with the diameter of optical dipole trap around 2.7um. Similar gratings are designed for guiding 780 nm probe laser to excite and also collect the fluorescence of 87Rb atoms. Such a device provides a compact solution for future applications of single atoms, including the single photon source, single-atom quantum register, and sensor.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Dissipative Kerr soliton (DKS) offers a compact solution of coherent comb sources and holds huge potential for applications, but has long been suffering from poor power conversion efficiency when driving by a continuous-wave laser. Here, a general approach to resolving this challenge is provided. By deriving the critical coupling condition of a multimode nonlinear optics system in a generalized theoretical framework, two efficiency limitations of the conventional pump method of DKS are revealed: the effective coupling rate is too small and is also power-dependent. Nonlinear couplers are proposed to sustain the DKS indirectly through nonlinear energy conversion processes, realizing a power-adaptive effective coupling rate to the DKS and matching the total dissipation rate of the system, which promises near-unity power conversion efficiencies. For instance, a conversion efficiency exceeding $90\:\%$ is predicted for aluminum nitride microrings with a nonlinear coupler utilizing second-harmonic generation. The nonlinear coupler approach for high-efficiency generation of DKS is experimentally feasible as its mechanism applies to various nonlinear processes, including Raman and Brillouin scattering, and thus paves the way of micro-solitons towards practical applications.