Coupling mechanical motion to an optical resonator enables displacement measurements approaching the standard quantum limit (SQL). However, increasing the optomechanical coupling strength will inevitably lead to probing of the nonlinear response of the optical resonator. Thermal intermodulation noise (TIN) arising from the nonlinear mixing of thermomechanical motion can further increase the imprecision well above the SQL and has hitherto been canceled up to second order of nonlinearity via operation at the "magic detuning". In this work, we record the output of a membrane-in-the-middle microcavity system operating at room temperature and achieving high cooperativity, $C>n_\text{th}$, and apply a nonlinear transform that removes all orders of TIN, improving the mechanical signal-to-noise ratio by nearly 10 dB. Our results can be applied to experiments affected by third-order TIN, which we expect to be the dominating intrinsic source of noise in high-cooperativity room-temperature cavity optomechanical systems.
High-quality microring resonators (MRRs) have proven to be promising sources of optical combs generated from continuous-wave radiation. In addition to the primary comb that propagates along with the pump, Rayleigh scattering creates a comb that travels in the opposite direction. Normally, the scattering is a very weak, however, in the high-quality-factor MRR the power transferred to the backward-propagating comb can be quite significant. We demonstrate that the backward-propagating comb can be used as a feedback source for a fiber laser, effectively creating a nonlinear mirror for the laser cavity. By assembling a simple laser cavity comprising only active fiber and two mirrors, one of which is an integrated MRR, we show a robust self-starting comb generation with width exceeding 500 nm. We confirm the universal character of this approach for other types of microresonators, including whispering gallery mode resonators, by launching self-starting laser cavity combs with the crystalline toroidal cavity, coupled with a tapered fiber. This method provides significant simplification for the filter-driven laser cavity soliton generation, especially when free-space coupling is applied.
Landmine detection using traditional methods is slow, dangerous and prohibitively expensive. Using deep learning-based object detection algorithms drone videos is promising but has multiple challenges due to the small, soda-can size of recently prevalent surface landmines. The literature currently lacks scientific evaluation of optimal ML models for this problem since most object detection research focuses on analysis of ground video surveillance images. In order to help train comprehensive models and drive research for surface landmine detection, we first create a custom dataset comprising drone images of POM-2 and POM-3 Russian surface landmines. Using this dataset, we train, test and compare 4 different computer vision foundation models YOLOF, DETR, Sparse-RCNN and VFNet. Generally, all 4 detectors do well with YOLOF outperforming other models with a mAP score of 0.89 while DETR, VFNET and Sparse-RCNN mAP scores are all around 0.82 for drone images taken from 10m AGL. YOLOF is also quicker to train consuming 56min of training time on a Nvidia V100 compute cluster. Finally, this research contributes landmine image, video datasets and model Jupyter notebooks at https://github.com/
A mathematician working at Anthropic says he used the AI model Claude Fable 5 to uncover a remarkably simple counterexample to the Jacobian conjecture, a famous problem that has resisted mathematicians for more than a century。 The result shows that the conjecture is false in three dimensions and above, although the original two-dimensional version
NASA astronaut Chris Williams and two Roscosmos cosmonauts are back on Earth after spending 241 days aboard the International Space Station。 Their journey covered more than 102 million miles and included 3,856 trips around the planet
Scientists traced a mysterious surge of low-energy gamma rays from zinc-70 to magnetic changes occurring inside its nucleus。 The breakthrough could improve models of how stars, supernovae, and neutron star mergers create heavy elements
NASA’s Swift Observatory observed a supermassive black hole ripping apart a star more than 30,000 light-years from the center of a distant galaxy。 The extraordinary flare briefly outshone its entire host galaxy in ultraviolet light and revealed a black hole about a million times the Sun’s mass
A new 3D printing technique can produce exceptionally hard tungsten carbide cobalt while using less of its expensive raw materials。 By softening rather than fully melting the material, researchers created defect-free samples with industrial-grade hardness and opened the door to more efficient manufacturing
Scientists have demonstrated that heat can move through a crystal in focused, wave-like rays at room temperature instead of spreading randomly。 The breakthrough could make it possible to route heat around sensitive parts of next-generation chips and quantum devices
Researchers have found a way to build much larger “twisted” oxide materials while precisely controlling how their atomic layers line up。 Because these materials can be made over large areas and transferred onto different surfaces, the technique could help turn twistronics from a laboratory curiosity into a practical platform for next-generation ele
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A black hole observed during a dramatic 2023 eruption did not simply devour gas from its nearby companion star。 It also expelled large amounts of material through powerful jets and winds, even after the outburst had nearly faded。 The results suggest black holes may continue reshaping their surroundings long after their brightest fireworks end
The solar wind may be stripping away Mars’ atmosphere by creating giant rolling waves along its outer edge。 Data from MAVEN and Tianwen-1 show that these waves form plasma clouds that carry atmospheric particles into space。 The process is concentrated on one side of Mars and may have played a major role in drying out the once potentially habitable
Physicists have uncovered a surprising limit to electrical resistance caused by particles colliding。 Using ultracold potassium atoms trapped in a grid of light, researchers created a highly controlled stand-in for electrons moving through a solid。 As collisions became more frequent and intense, resistance initially rose, but eventually hit a ceilin
Europa’s hidden ocean has made the icy moon one of the solar system’s most promising places to search for habitable conditions。 Scientists have hoped that water from this deep ocean might rise through cracks and form shallow reservoirs that future spacecraft could more easily study。 New simulations suggest that journey is unlikely because turbulent