理学最新文献

Quantum optics has advanced our understanding of the nature of light and enabled applications far beyond what is possible with classical light. The unique capabilities of quantum light have inspired the migration of some conceptual ideas to the realm of classical optics, focusing on replicating and exploiting non-trivial quantum states of discrete-variable systems. Here, we further develop this paradigm by building the analogy of quantum squeezed states using classical structured light. We have found that the mechanism of squeezing, responsible for beating the standard quantum limit in quantum optics, allows for overcoming the “standard spatial limit” in classical optics: the light beam can be “squeezed” along one of the transverse directions in real space (at the expense of its enlargement along the orthogonal direction), where its width becomes smaller than that of the corresponding fundamental Gaussian mode. We show that classical squeezing enables nearly sub-diffraction and superoscillatory light focusing, which is also accompanied by the nanoscale phase gradient of the size in the order of λ/100 (λ/1000), demonstrated in the experiment (simulations). Crucially, the squeezing mechanism allows for continuous tuning of both features by varying the squeezing parameter, thus providing distinctive flexibility for optical microscopy and metrology beyond the diffraction limit and suggesting further exploration of classical analogies of quantum effects.

A novel dual-mode optical vector spectrum analyzer is demonstrated that is suitable for the characterization of both passive devices as well as active laser sources. It can measure loss, phase response, and dispersion properties over a broad bandwidth, with high resolution and dynamic range.

Quantum walks provide a speed-up in computational power for various quantum algorithms and serve as inspiration for the construction of complex graph representations. Many pioneering works have been dedicated to expanding the experimental state space and the complexity of graphs. However, these experiments are mostly limited to small experimental scale, which do not reach a many-body level and fail to reflect the multi-particle quantum interference effects among non-adjacent modes. Here, we present a quantum walk with three photons on a two-dimensional triangular lattice, which is mapped to a 19 × 19 × 19 high-dimensional state space and constructs a complex graph with 6859 nodes and 45,486 edges. By utilizing the statistical signatures of the output combinations and incorporating machine learning techniques, we successfully validate the nonclassical properties of the experiment. Our implementation provides a paradigm for exponentially expanding the state space and graph complexity of quantum walks, paving the way for surmounting the classical regime in large-scale quantum simulations.

Mid-infrared (MIR) fiber lasers are important for a wide range of applications in sensing, spectroscopy, imaging, defense, and security. Some progress has been made in the research of MIR fiber lasers based on soft glass fibers, however, the emission range of rare-earth ions and the robustness of the host materials are still a major challenge for MIR fiber lasers. The large number of gases provide a variety of optical transitions in the MIR band. When combined with recent advances in low-loss hollow-core fiber (HCF), there is a great opportunity for gas-filled fiber lasers to further extend the radiation to the MIR region. Here, a 4.8-μm CO-filled silica-based HCF laser is reported for the first time. This is enabled by an in-house manufactured broadband low-loss HCF with a measured loss of 1.81 dB/m at 4.8 μm. A maximum MIR output power of 46 mW and a tuning range of 180 nm (from 4644 to 4824 nm) are obtained by using an advanced 2.33-μm narrow-linewidth fiber laser. This demonstration represents the longest-wavelength silica-based fiber laser to date, while the absorption loss of bulk silica at 4824 nm is up to 13, 000 dB/m. Further wavelength expansion could be achieved by changing the pump absorption line and optimizing the laser structure.

The detection of gravitational waves has ushered in a new era of observing the universe. Quantum resource advantages offer significant enhancements to the sensitivity of gravitational wave observatories. While squeezed states for ground-based gravitational wave detection have received marked attention, the generation of squeezed states suitable for mid-to-low-frequency detection has remained unexplored. To address the gap in squeezed state optical fields at ultra-low frequencies, we report on the first direct observation of a squeezed vacuum field until Fourier frequency of 4 millihertz with the quantum noise reduction of up to 8.0 dB, by the employment of a multiple noise suppression scheme. Our work provides quantum resources for future gravitational wave observatories, facilitating the development of quantum precision measurement.

To establish a scalable and secure quantum network, a critical milestone is advancing from basic point-to-point quantum key distribution (QKD) systems to the development of inherently multi-user protocols designed to maximize network capacity. Here, we propose a quantum passive optical network (QPON) protocol based on continuous-variable (CV) systems, particularly the quadrature of the coherent state, which enables deterministic, simultaneous, and high-rate secret key generation among all network users. We implement two protocols with different trust levels assigned to the network users and experimentally demonstrate key generation in a quantum access network with 8 users, each with an 11 km span of access link. Depending on the trust assumptions about the users, we reach 1.5 and 2.1 Mbits/s of total network key generation (or 0.4 and 1.0 Mbits/s with finite-size channels estimation). Demonstrating the potential to expand the network’s capacity to accommodate tens of users at a high rate, our CV-QPON protocols open up new possibilities in establishing low-cost, high-rate, and scalable secure quantum access networks serving as a stepping stone towards a quantum internet.

Hybrid tandem perovskite-organic LED has been developed to achieve high external quantum efficiency, narrow linewidth, and extended device lifespan, which shows great promise for future perovskite-EL-based commercial applications.

Nonlinear optics plays an important role in many areas of science and technology. The advance of nonlinear optics is empowered by the discovery and utilization of materials with growing optical nonlinearity. Here we demonstrate an indium gallium phosphide (InGaP) integrated photonics platform for broadband, ultra-efficient second-order nonlinear optics. The InGaP nanophotonic waveguide enables second-harmonic generation with a normalized efficiency of 128, 000%/W/cm² at 1.55 μm pump wavelength, nearly two orders of magnitude higher than the state of the art in the telecommunication C band. Further, we realize an ultra-bright, broadband time-energy entangled photon source with a pair generation rate of 97 GHz/mW and a bandwidth of 115 nm centered at the telecommunication C band. The InGaP entangled photon source shows high coincidence-to-accidental counts ratio CAR > 10⁴ and two-photon interference visibility > 98%. The InGaP second-order nonlinear photonics platform will have wide-ranging implications for non-classical light generation, optical signal processing, and quantum networking.

Low-cost, high-performance, and uncooled broadband photodetectors (PDs) have potential applications in optical communication etc., but it still remains a huge challenge to realize deep UV (DUV) to the second near-infrared (NIR-II) detection for a single broadband PD. Herein, a single PD affording broadband spectral response from 200 to 1700 nm is achieved with a vertical configuration based on quantum dots (QDs) heterojunction and quantum cutting luminescent concentrators (QC–LC). A broadband quantum dots heterojunction as absorption layer was designed by integrating CsPbI₃:Ho³⁺ perovskite quantum dots (PQDs) and PbS QDs to realize the spectral response from 400 to 1700 nm. The QC–LC by employing CsPbCl₃:Cr³⁺, Ce³⁺, Yb³⁺, Er³⁺ PQDs as luminescent conversion layer to collect and concentrate photon energy for boosting the DUV–UV (200–400 nm) photons response of PDs by waveguide effect. Such broadband PD displays good stability, and outstanding sensitivity with the detectivity of 3.19 × 10¹² Jones at 260 nm, 1.05 × 10¹³ Jones at 460 nm and 2.23 × 10¹² Jones at 1550 nm, respectively. The findings provide a new strategy to construct broadband detector, offering more opportunities in future optoelectronic devices.