Nanowerk November 27, 2024 Lightweight, low-cost metasurfaces and reflect arrays that are easy to stow and deploy are desirable for many terrestrial and space-based communications and sensing applications. A team of researchers in the US ( Columbia University, North Carolina State University, City University of New York) demonstrated a lightweight, flexible metasurface platform based on flat-knit textiles operating in the cm-wave spectral range. By using float-jacquard knitting to directly integrate an array of resonant metallic antennas into a textile, two textile reflect array devices, a metasurface lens (metalens), and a vortex-beam generator were realized. Operating as a receiving antenna, the […]
Tag Archives: Communications technology
Test of a prototype quantum internet runs under New York City for half a month
Phys.org August 24, 2024 The distribution of high-fidelity high-rate entanglement over telecommunication infrastructure is one of the main paths toward large-scale quantum networks, enabling applications such as quantum encryption and network protection, blind quantum computing, distributed quantum computing, and distributed quantum sensing. However, the fragile nature of entangled photons operating in real-world fiber infrastructure has historically limited continuous operation of such networks. A company in New York presented a fully automated system capable of distributing polarization-entangled photons over a 34-km deployed fiber in New York City, achieving high rates of nearly 5×105 pairs/s. They demonstrated high fidelity of approximately 99% […]
Flat optics revolutionize quantum light sources for enhanced communication and sensing
Nanowerk April 25, 2024 Recent advancements have witnessed a significant shift toward the utilization of “flat” optics with thickness at subwavelength scales for the development of quantum light sources. This approach offers notable advantages over conventional bulky counterparts, including compactness, scalability, and improved efficiency, along with added functionalities. In this review researchers in Australia focused on the recent advances in leveraging flat optics to generate quantum light sources. Specifically, the generation of entangled photon pairs through spontaneous parametric down-conversion in nonlinear metasurfaces, and single photon emission from quantum emitters including quantum dots and color centers in 3D and 2D materials […]
New metasurface innovation unlocks precision control in wireless signals
Nanowerk April 22, 2023 Polarization conversion and beam scanning metasurfaces are commonly used to reduce polarization mismatch and direct electromagnetic waves in a specific direction to improve the strength of a wireless signal. However, identifying suitable active and mechanically reconfigurable metasurfaces for polarization conversion and beam scanning is a considerable challenge, and the reported metasurfaces have narrow scanning ranges, are expensive, and cannot be independently controlled. Researchers in South Korea proposed a reconfigurable transmissive metasurface combined with a scissor and rotation actuator for independently controlling beam scanning and polarization conversion functions. They constructed metasurface with rotatable unit cells (UCs) that […]
Could new technique for ‘curving’ light be the secret to improved wireless communication?
Science Daily April 9, 2024 A key challenge in millimeter-wave and terahertz wireless networks is blockage of the line-of-sight path between a base station and a user. A team of engineers in the US (University of Missouri-Kansas City, Rice University, Brown University) proposed a solution to this problem leveraging the fact that, in such scenarios, users are likely to be located within the electromagnetic near field of the base station, which opens the possibility to engineer wave fronts for link maintenance. They showed that curved beams, carrying data at high bit rates, could realize a link by curving around an […]
Waterproof ‘e-glove’ could help scuba divers communicate
Nanowerk April 10, 2024 Existing tactile sensing gloves fall short in terms of user comfort and are ill-suited for underwater applications. Researchers in China proposed and constructed a flexible hand gesture recognition glove (GRG) that contained high-performance micropillar tactile sensors (MPTSs) inspired by the flexible tube foot of a starfish. The sensor has a wide working range, superfast response time, reliable repeatability, and a low limit of detection and they were waterproof. When integrated with machine learning algorithm, the GRG system achieved intelligent recognition of 16 hand gestures under water, extending real-time and effective communication capabilities for divers. According to […]
100 kilometers of quantum-encrypted transfer
Phys.org April 2, 2024 Continuous-variable (CV) quantum key distribution (QKD) with coherent states and coherent detection integrates well with existing telecommunication networks. Thus far, long-distance CV-QKD has only been demonstrated using a highly complex scheme where the local oscillator is transmitted, opening security loopholes for eavesdroppers, and limiting potential applications. Researchers in Denmark have demonstrated a long-distance CV-QKD experiment with a locally generated oscillator over a 100-kilometer fiber channel with a total loss of 15.4 decibels. This was done by controlling the phase noise–induced excess noise through a machine learning framework for carrier recovery and optimizing the modulation variance. They […]
Deciphering quantum enigmas: The role of nonlocal boxes in defining the boundaries of physical feasibility
Phys.org February 14, 2024 Nonsignaling boxes (NS) are theoretical resources defined by the principle of no-faster-than-light communication. They generalize quantum correlations and some of them are known to collapse communication complexity (CC). However, this collapse is strongly believed to be unachievable in nature. An international team of researchers (France, Canada) provided intuition on which theories are unrealistic. They found a better sufficient condition for a nonlocal box to collapse CC, thus extended the known collapsing region. In some slices of NS, they showed that this condition coincides with an area outside of an ellipse… read more. TECHNICAL ARTICLE Full […]
Photonic crystals bend light as though It were under the influence of gravity
Nanowerk October 16, 2023 An international team of researchers (Japan, Spain) demonstrated electromagnetic waves following a gravitational field using a photonic crystal. They introduced spatially distorted photonic crystals (DPCs) capable of deflecting light waves owing to their pseudo gravity caused by lattice distortion. They experimentally verified the phenomenon in the terahertz range using a silicon DPC. Pseudo gravity caused by lattice distortion revealed alternative approaches to achieve on-chip trajectory control of light propagation in PCs. Their work has far-reaching implications for the world of optics and materials science, and bear significance for the development of 6G communications… read more. TECHNICAL […]
Toward metropolitan free-space quantum networks
Phys.org October 10, 2023 An international team of researchers (Germany, Austria) developed a deployable free-space QKD system and demonstrated its use in realistic scenarios. They developed and launched a low-Earth-orbit satellite for implementing decoy-state QKD—a form of QKD that uses weak coherent pulses at high channel loss and was secure because photon-number-splitting eavesdropping could be detected. They achieved a kilohertz key rate from the satellite to the ground over up to 1,200 kilometres. The key rate was around 20 orders of magnitudes greater than that expected using an optical fibre of the same length. According to the researchers their work […]