Microcomb-synchronized optoelectronics
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Vernier microcombs for integrated optical atomic clocks
Kerr microcombs have drawn substantial interest as mass-manufacturable, compact alternatives to bulk frequency combs. This could enable the deployment of many comb-reliant applications previously confined to laboratories. Particularly enticing is the prospect of microcombs performing optical frequency division in compact optical atomic clocks. Unfortunately, it is difficult to meet the self-referencing requirement of microcombs in these systems owing to the approximately terahertz repetition rates typically required for octave-spanning comb generation. In addition, it is challenging to spectrally engineer a microcomb system to align a comb mode with an atomic clock transition with a sufficient signal-to-noise ratio. Here we adopt a Vernier dual-microcomb scheme for optical frequency division of a stabilized ultranarrow-linewidth continuous-wave laser at 871 nm to an ~235 MHz output frequency. This scheme enables shifting an ultrahigh-frequency (~100 GHz) carrier-envelope offset beat down to frequencies where detection is possible and simultaneously placing a comb line close to the 871 nm laser—tuned so that, if frequency doubled, it would fall close to the clock transition in 171Yb+. Our dual-comb system can potentially combine with an integrated ion trap towards future chip-scale optical atomic clocks.
Integrating molecular photoswitch memory with nanoscale optoelectronics for neuromorphic computing
Photonic solutions are potentially highly competitive for energy-efficient neuromorphic computing. However, a combination of specialized nanostructures is needed to implement all neuro-biological functionality. Here, we show that donor-acceptor Stenhouse adduct dyes integrated with III-V semiconductor nano-optoelectronics have combined excellent functionality for bio-inspired neural networks. The dye acts as synaptic weights in the optical interconnects, while the nano-optoelectronics provide neuron reception, interpretation and emission of light signals. These dyes can reversibly switch from absorbing to non-absorbing states, using specific wavelength ranges. Together, they show robust and predictable switching, low energy thermal reset and a memory dynamic range from days to sub-seconds that allows both short- and long-term memory operation at natural timescales. Furthermore, as the dyes do not need electrical connections, on-chip integration is simple. We illustrate the functionality using individual nanowire photodiodes as well as arrays. Based on the experimental performance metrics, our on-chip solution is capable of operating an anatomically validated model of the insect brain navigation complex.
Observation of non-Hermitian topological synchronization
Non-Hermitian topology plays a pivotal role in physical science and technology, exerting a profound impact across various scientific disciplines. Recently, the interplay between topological physics and nonlinear synchronization has aroused a great interest, leading to the emergence of an intriguing phenomenon known as topological synchronization, wherein nonlinear oscillators at boundaries synchronize through topological boundary states. To the best of our knowledge, however, this phenomenon has yet to be experimentally validated, and the study of non-Hermitian topological synchronization remains in its infancy. Here, we investigate non-Hermitian topological synchronization, uncovering the influence of system size and boundary site geometry on synchronization effects. We demonstrate that simply varying the lattice size allows transitions between three distinct types of non-Hermitian topological synchronization. Furthermore, we reveal that the geometry of the boundary sites introduces a degree of freedom, enabling the control over the configuration of non-Hermitian topological synchronization. These findings are experimentally validated using non-Hermitian nonlinear topological circuits. This work significantly broadens the scope of nonlinear non-Hermitian topological physics and opens new avenues for the application of synchronization phenomena in future technologies.
Ultrasensitive photoelectric detection with room temperature extremum
Room-temperature photodetection holds pivotal significance in diverse applications such as sensing, imaging, telecommunications, and environmental remote sensing due to its simplicity, versatility, and indispensability. Although different kinds of photon and thermal detectors have been realized, high sensitivity of photodetection with room temperature extremum is not reported until now. Herein, we find evident peaks in the photoelectric response originated from the anomalous excitonic insulator phase transition in tantalum nickel selenide (Ta2NiSe5) for room-temperature optimized photodetection from visible light to terahertz ranges. Extreme sensitivity of photoconductive detector with specific detectivity (D*) of 5.3 × 1011 cm·Hz1/2·W−1 and electrical bandwidth of 360 kHz is reached in the terahertz range, which is one to two orders of magnitude improvement compared to that of the state-of-the-art room-temperature terahertz detectors. The van der Waals heterostructure of Ta2NiSe5/WS2 is further constructed to suppress the dark current at room temperature with much improved ambient D* of 4.1 × 1012 cm·Hz1/2·W−1 in the visible wavelength, rivaling that of the typical photodetectors, and superior photoelectric performance in the terahertz range compared to the photoconductor device. Our results open a new avenue for optoelectronics via excitonic insulator phase transition in broad wavelength bands and pave the way for applications in sensitive environmental and remote sensing at room temperature.
Epigenetic regulation of HOXA2 expression affects tumor progression and predicts breast cancer patient survival
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