Science Daily November 18, 2022 Understanding the factors affecting energy loss in organic photovoltaics (OPVs) is imperative to achieve further improvements in their efficiency and to establish design rules for the development of new materials. By studying several planar and bulk heterojunction solar cells, an international team of researchers (USA – Princeton University, Saudi Arabia) has demonstrated that the non-radiative energy loss component quadratically increases with increasing Gaussian CT-state disorder. They showed that by defining the total energy loss in terms of the peak of the CT-state distribution the effect of disorder on OPV performance can be unambiguously identified, offering […]
An on-chip time-lens generates ultrafast pulses
Science Daily November 11, 2022 Integrated femtosecond pulse and frequency comb sources are critical components for a wide range of applications, including microwave photonics, communications, lidar, optical computing, and astronomy among other things. A team of researchers in the US (Harvard University, UCLA, Columbia University, industry) has demonstrated a chip-scale femtosecond pulse source implemented on an integrated lithium niobate photonic platform forming a time-lens system. The device was driven by a continuous-wave distributed feedback laser chip and controlled by a single continuous-wave microwave source without the need for any stabilization or locking. They measured femtosecond pulse trains with a 30-gigahertz […]
Researchers control individual light quanta at very high speed
Phys.org November 21, 2022 An international team of researchers (Spain, Germany) fabricated a dynamically reconfigurable integrated photonic circuit comprising integrated quantum dots (QDs), a Mach-Zehnder interferometer (MZI) and surface acoustic wave (SAW) transducers directly fabricated on a monolithic semiconductor platform to demonstrate on-chip single photon generation by the QD and its sub-nanosecond dynamic on-chip control. Two independently applied SAWs piezo-optomechanically rotated the single photon in the MZI. In the MZI, SAWs imprinted a time-dependent optical phase and modulated the qubit rotation to the output superposition state. This enabled dynamic single photon routing with frequencies exceeding one gigahertz. The combination of […]
Researchers develop phase-change key for new hardware security
Nanowerk November 18, 2022 An international team of researchers (Singapore, UK, South Korea) has developed a new type of hardware security device called physical unclonable function (PUF) using phase-change materials. They fabricated devices switch reversibly between the glassy amorphous state and crystal orderly state. Then they used the variation in the device’s electrical conductance to construct the PUF due to the inherent randomness arising from the manufacturing process, which is not shown by conventional silicon-based devices. They modelled the characteristics of actual phase-change devices to generate a simulation of many phase-change-based PUFs and tested their security using machine learning. They […]
Researchers unlock light-matter interactions on sub-nanometer scales, leading to ‘picophotonics’
Phys.org November 16, 2022 The concept of photonic frequency-momentum (ω-q) dispersion has been extensively studied in artificial dielectric structures such as photonic crystals and metamaterials, but not in in natural materials at the atomistic level. Researchers at Purdue University have developed a Maxwell Hamiltonian theory of matter combined with the quantum theory of atomistic polarization to obtain the electrodynamic dispersion of natural materials interacting with the photon field. They applied this theory to silicon and discovered the existence of anomalous atomistic waves. These waves occur in the spectral region where propagating waves are conventionally forbidden in a macroscopic theory. According […]
Scientists synthesize an analog of the Earth’s most complex mineral in a laboratory
Phys.org November 21, 2022 Through the combination of low-temperature hydrothermal synthesis and room-temperature evaporation an international team of researchers (Russia, Czech Republic, USA – University of Notre Dame) has synthesized a mineral similar in composition and crystal structure to the Earth’s most complex mineral, ewingite. The crystal structures of both natural and synthetic compounds were based on supertetrahedral uranyl-carbonate nanoclusters that are arranged according to the cubic body-centered lattice principle. The structure and composition of the uranyl carbonate nanocluster were refined using the data on synthetic material. Although the stability of natural ewingite is higher (according to visual observation and […]
‘SuperGPS’ Technology Accurately Pinpoints Your Position Within Inches
Science Alert November 23, 2022 Although GNSS can provide centimetre-level precision, GNSS receivers are prone to many-metre errors owing to multipath propagation and an obstructed view of the sky, which occur particularly in urban areas where accurate positioning is most needed. Moreover, the vulnerabilities of GNSS, combined with the lack of a back-up system, pose a severe risk to GNSS-dependent technologies. Researhers in the Netherlands have demonstrated a terrestrial positioning system that is independent of GNSS and offers superior performance through a constellation of radio transmitters, connected and time-synchronized at the subnanosecond level through a fibre-optic Ethernet network. Using optical […]
Unabated Carbon Is Shrinking Earth’s Upper Atmosphere, Scientists Warn
Science Alert November 22, 2022 A team of researchers in the US (NASA Langley Research Center, industry, NCAR, University of Colorado, Catholic University of America, NASA Langley Research Center, Hampton University) examined the thermal structure of the mesosphere and lower thermosphere (MLT) using observations from 2002 through 2021 from the NASA satellite. They showed that the MLT has significantly cooled and contracted between the years 2002 and 2019 due to a combination of a decline in the intensity of the 11-year solar cycle and increasing CO2. During this time the thickness of atmosphere between approximately 48 and 105 km has […]
Top 10 Science and Technology Inventions for the Week of November 18, 2022
01. Electrons zip along quantum highways in new material 02. Ensuring AI works with the right dose of curiosity 03. A navigation system with 10 centimeter accuracy 04. New communications technology: Super-fast optical lasers 05. New strategy to effectively prevent component failures in metals 06. New theory of electron spin to aid quantum devices 07. Next generation material that adapts to its history 08. Unimon – A new qubit to boost quantum computers for useful applications 09. Researchers develop a material that mimics how the brain stores information 10. Transforming bacterial cells into living artificial neural circuits And others… Atomically […]
Atomically dispersed bimetallic iron–cobalt electrocatalysts developed for green production of ammonia
Phys.org November 14, 2022 Electrosynthesis of ammonia from nitrogen reduction reaction (NRR) at ambient conditions has been widely regarded as a green ammonia synthesis technology to replace the traditional energy- and capital-intensive Haber-Bosch process. Although single-atom electrocatalysts (SACs) may create a new catalytic paradigm, one of the key challenges hindering the rational design and development of SACs is the lack of insight into the relationship between performance and SA loading. An international team of researchers (China, Australia) demonstrated an adsorption-regulated synthetic method that uses bacterial cellulose as an adsorption regulator to control Fe3+/Co2+ impregnation on bacterial cellulose through carbothermal reduction. […]