分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: We report a new technique for the realization of second-order correlation ($g^2(\tau)$) measurement under low-repetition-rate pulsed excitation (1 kHz), with timing jitter calibrated to restore lateral $g^2(\tau)$ curves and determine $g^2(0)$. We use CdSe nanowire (NW) laser to demonstrate the jitter-calibrated $g^2(\tau)$ measurement, where $g^2(0)$ evolution shows the laser emission transition process. The exciting pulses are split into reference and excitation channels, which enables the jitter calibration when the exciting pulses have significant timing jitter and low repetition rate. After using the reference signals to calibrate and rearrange the single-photon signals, lateral $g^2(\tau)$ curves can be entirely restored, and $g^2(0)$ evolution is demonstrated from our method.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: We demonstrate ultra-high Q factor microring resonators close to the intrinsic material absorption limit on lithium niobate on insulator. The microrings are fabricated on pristine lithium niobate (LN) thin film wafer thinned from LN bulk via chemo-mechanical etching without ion slicing and ion etching. A record-high Q factor up to times ten to the power of 8th at the wavelength of 1550 nm is achieved because of the ultra-smooth interface of the microrings and the absence of ion induced lattice damage, indicating an ultra-low waveguide propagation loss of about 0.28 dB per meter. The ultra-high Q microrings will pave the way for integrated quantum light source, frequency comb generation, and nonlinear optical processes.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: The nonlinear optical radiation of an integrated lithium niobate microcavity is demonstrated, which has been neglected in previous studies of nonlinear photonic devices. We find that the nonlinear coupling between confined optical modes on the chip and continuum modes in free space can be greatly enhanced on the platform of integrated microcavity, with feasible relaxation of the phase-matching condition. With an infrared pump laser, we observe the vertical radiation of second-harmonic wave at the visible band, which indicates a robust phase-matching-free chip-to-free-space frequency converter and also unveils an extra energy dissipation channel for integrated devices. Such an unexpected coherent nonlinear interaction between the free-space beam and the confined mode is also validated by the different frequency generation. Furthermore, based on the phase-matching-free nature of the nonlinear radiation, we build an integrated atomic gas sensor to characterize Rb isotopes with a single telecom laser. The unveiled mechanism of nonlinear optical radiation is universal for all dielectric photonic integrated devices, and provides a simple and robust chip-to-free-space as well as visible-to-telecom interface.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Accurate control of single emitters at nanophotonic interfaces may greatly expand the accessible quantum states of coupled optical spins in the confined geometry and to unveil exotic nonlinear quantum optical effects. However, the optical control is challenged by spatially varying light-atom coupling strength generic to nanophotonics. We demonstrate numerically that despite the near-field inhomogenuity, nearly perfect atomic state control can be achieved by exploiting geometric robustness of optical transitions with composite picosecond excitations. Our proposal is followed by a proof-of-principle demonstration where an $N=3$ composite sequence is applied to robustly invert the D1 population of free-flying $^{85}$Rb atoms trespassing a nanofiber interface. The precise control is confirmed by comparing the D2 fiber transmission with full-level simulation of the mesoscopic light-atom interaction across the composite parameter space. We project the scheme to large $N$ for precise phase patterning and arbitrary optical dipole control at the nanophotonic interface.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Coherently driven semiconductor quantum dots are one of the most promising platforms for non-classical light sources and quantum logic gates which form the foundation of photonic quantum technologies. However, to date, coherent manipulation of quantum dots is limited mainly to their lowest orbital states. Ultrafast coherent control of high-orbital states is obstructed by the demand for tunable terahertz pulses. To break this constraint, we demonstrate an all-optical method to control high-orbital states of a hole via stimulated Auger process. The coherent nature of the Auger process is revealed by Rabi oscillation and Ramsey interference with a fidelity of 95.8%. Harnessing this coherence further enables the investigation of single-hole relaxation mechanism. A surprisingly long relaxation time (156(2) ps) is observed and explained by phonon bottleneck effect. Our work opens new possibilities for understanding the fundamental properties of high-orbital states in quantum emitters and developing new types of orbital-based quantum photonic devices.