Wellspennington6766

Our work sheds new light on computational hardness of FBS by identifying the mathematical connection between BosonSampling with quantum and classical light.We propose and experimentally demonstrate a continuously tunable all-optical microwave filter based on a photonic crystal (PC) L3 cavity. Due to the small cavity mode volume and prominent optical properties, the required power to arouse the cavity nonlinear effects is low as microwatt level. Moreover, the cavity resonance could be continuously shifted by finely adjusting the input powers. Therefore, under optical single sideband modulation, the frequency interval between the optical carrier and cavity resonance could be controllable. In this case, the central frequency of the microwave photonic filter (MPF) could be continuously tuned with low power consumption. To the best of our knowledge, the experimental tuning efficiency of 101.45 GHz/mW is a record for on-chip tunable all-optical microwave filters. With dominant features of all-optical control, ultra-high tuning efficiency (101.45 GHz/mW), large rejection ratios (48 dB) and compact footprint (100 µm2), the proposed silicon nanocavity is competent to process microwave signals, which has many useful applications in on-chip energy-efficient microwave photonic systems.We present integration of singulated micron-sized light emitting diodes (micro-LEDs) directly onto a silicon CMOS drive chip using a transfer printing method. An 8x8 micro-LED device array with individual control over each pixel is demonstrated with modulation bandwidths up to 50 MHz, limited by the large modulation depth of the driver chip. The 2 kHz frame rate CMOS driver also incorporates a Single Photon Avalanche Diode device thus allowing detection and transmission functionality on a single integrated chip. Visible light communications at data rates up to 1 Mbps, and time-of-flight ranging with cm-scale resolution are demonstrated using this hybrid integrated system.Interference microscopy is a powerful optical imaging technique providing quantitative phase distribution information to characterize various type technical and biomedical objects. Static and dynamic objects and processes can be investigated. In this paper we propose very compact, common-path and partially coherent diffraction grating-based interference microscopy system for studying small objects like single cells with low densities being sparsely distributed in the field of view. Simple binary amplitude diffraction grating is the only additional element to be introduced into a conventional microscope optical system. By placing it at a proper distance in front of the microscope image plane the total-shear operation mode is deployed resulting in interferograms of the object-reference beam type. Depending on the grating to image plane separation distance two or three-beam interferograms are generated. The latter ones are advantageous since they contain achromatic second harmonics in the interferogram intensity distributions. This feature enables to use reduced temporal coherence light sources for the microscope to reduce coherent noise and parasitic interference patterns. For this purpose we employ the laser diode with driving current below the threshold one. Results of conducted experiments including automatic computer processing of interferograms fully corroborate analytical description of the proposed method and illustrate its capabilities for studying static and dynamic phase objects.Superradiant active clocks operating on narrow linewidth clock transitions are predicted to achieve precision orders of magnitude higher than any currently existing optical atomic clocks. We introduce a theory of superradiant lasing and implement it for the example of 40Ca atoms. The presented model, however, is valid for any two- or three-level system in an optical lattice. We perform a feasibility analysis and suggest a set of parameters for the experimental fulfillment of superradiant lasing in Ca. Moreover, we present an overview of different magic wavelengths for the 4s2 1S0 ↔ 4s4p3P1 (mJ = 0) transition in Ca for different polarizations and a robustness analysis of these magic conditions. We also report the magic-zero wavelengths for the 4s4p3P1, mJ = 0 state.We realize a high-stability laser by modulation transfer spectroscopy and apply it to implement a high-performance compact optically pumped cesium beam atomic clock. Evaluated by the optical heterodyne method with two identical frequency-stabilized lasers, the frequency instability of the 852 nm laser directly referenced on thermal atoms is 2.6×10-13 at the averaging time of 5 s. Factors degrading the frequency stability of the laser are analyzed, and we will further control it to reduce the frequency noise of the laser. By comparing with a Hydrogen maser, the measured Allan deviation of the high-stability-laser-based cesium beam atomic clock is 2×10-12/τ, dropping to 1×10-14 in less than half a day of averaging time. To our knowledge, the Allan deviation of our cesium clock is better than that of any reported compact cesium beam atomic clocks at the averaging time of half-day. The high-performance atomic clock can promote the fields in metrology and timekeeping, and the high-stability laser additionally possesses great potential to be a compact optical frequency standard.Based on the rotational Doppler effect, an orbital angular momentum beam can measure the lateral rotation velocity of an object, which has broad application prospects. However, all existing research focus on the light spot center coinciding with the rotation center, or only with small center offset. IBET762 This is difficult to ensure in remote detection applications. In this paper, the rotational Doppler frequency shifts under three cases, including no center offset, small center offset and large center offset, are analyzed theoretically. Through theoretical research results, a novel method of measuring rotation velocity is proposed, with the light spot completely deviated out of the rotation center. A laboratory verification experiment shows that this proposed method breaks the limit of center offset of lateral rotation velocity measurement and is of great significance to the remote detection of non-cooperative rotation object.