Phys.org February 26, 2020 Researchers at Stanford University sought to imagine a new type of cooling device that would work by reversing the heat exchange between an object and its environment by adding energy to radiated photons—in theory, doing so should carry away more heat. They developed theoretical and computational formalisms to describe thermal radiation from temporally modulated systems. They showed that such a modulation results in a photon-based active cooling mechanism. This mechanism has a high thermodynamic performance that can approach the Carnot limit. The work points to exciting new avenues in active, time-modulated control of thermal emission for […]
Quantum researchers able to split one photon into three
Phys.org February 27, 2020 By splitting one “pump photon” into two daughter photons, SPDC has had a crucial role in fundamental tests of quantum theory as well as many applications in quantum information processing. An international team of researchers (Canada, Spain, Sweden) used a flux-pumped, superconducting parametric resonator to split one microwave photon into three daughter photons. The triplet source is bright, producing a propagating photon flux comparable to ordinary two-photon SPDC. They clearly saw strong three-photon correlations in the output photons, even in the absence of normal two-photon correlations. The symmetry properties of these correlations allowed them to “fingerprint” […]
Researchers create new state of light
Phys.org February 25, 2020 Light rotates around a longitudinal axis parallel to the direction light travels. An international team of researchers (China, USA – University of Dayton) has demonstrated a three-dimensional wave packet that is a spatiotemporal (ST) optical vortex with a controllable purely transverse orbital angular momentum (OAM). The magnitude of the transverse OAM carried by the ST vortex is scalable to a larger value by simple adjustments. Since the ST vortex carries a controllable OAM uniquely in the transverse dimension, it has strong potential for novel applications that may not be possible otherwise. The scheme reported here can […]
Scientists create new material for electronics of the future
Phys.org February 27, 2020 Barium ferrites are particularly interesting because they have unique functional properties. Researchers in Russia have created barium hexaferrite with various degrees of aluminum doping as their crystal structure allows to vary the properties of the material in the ranges needed for a particular device. They are studying the properties of the material in the frequency range of 32-50 GHz. It allows increasing the frequency range used in the production of electronic devices. Using powder form of the material they have shown that increases electronic device operational stability and reduces the cost of sintering. It can be […]
Shining a new light on biomimetic materials
Phys.org February 25, 2020 Self-trapped light beams hold potential for optical interconnects, applications in image transmission, rerouting light, logic gates for computing and for the next-generation light-guiding-light signal processing. However, self-trapping suffers from either the need for large incident beam power and loss of beam interactions at large distances, or it is slow and irreversible. An international team of researchers (Canada, USA – Harvard University, University of Pittsburgh) has shown that rapidly and repeatably switchable self-trapped laser beams with remote communication capabilities can be elicited at exceptionally small intensities in a pliant, processable hydrogel functionalized with a chromophore. According to […]
Simple self-charging battery offers power solutions for devices
Phys.org February 25, 2020 An international team of researchers (Portugal. USA – UT Austin) made a battery with two different metals as electrodes and a lithium-rich glass electrolyte which would feed both electrodes with lithium ions, on charge and discharge with no need for lithium metal. The electrochemical cell demonstrates an entanglement between negative resistance, negative capacitance, self-charge, self-cycling, and the activation energy vs thermal energy or external work. The phenomenon of self-cycling is enhanced at low temperatures where the activation energy is higher than the thermal energy. These batteries can be used in extremely low-frequency communications and in devices […]
Synthesizing a superatom: Opening doors to their use as substitutes for elemental atoms
Science Daily February 25, 2020 Scientists have shown particular interest in superatomic structures, since they can be linked with atoms to produce molecules, and potentially be used to substitute certain elements in many applications. But for superatoms to be effectively utilized, they must be specially tailored to resemble the characteristics of the corresponding elements. Researchers in Japan fabricated clusters of the element gallium in solution to demonstrate the effects of changing the number of atoms in a cluster on the properties of the cluster. The team synthesized Ga clusters of 3, 12, 13 using a specialized superatom synthesizer. The 13-atom […]
Team develops optical communications technology to double data transfer speed
Phys.org February 24, 2020 Researchers in South Korea have designed real-time pulse amplitude modulation-4 (PAM-4) digital signal processing including forward error correction for a C-band inter-datacenter network. The PAM-4 DSP is intended to compensate for chromatic dispersion and provide dispersion tolerance. A decision feedback equalizer and maximum likelihood sequence equalizer were employed for the dispersion compensation. A low-density parity check code was used to increase coding gain. They have empirically proved the feasibility of 25 km transmission without error-floor sign, corresponding to a dispersion compensation capacity of 425 ps/nm and confirmed 35 km ∼ 85 km error-free transmission for inter-datacenter […]
Using light to put a twist on electrons
Science Daily February 26, 2020 Chirality occurs not in the structure of the molecules themselves, but in a kind of patterning in the density of electrons within the material. An international team of researchers (USA – MIT, Carnegie Mellon, Northeastern University, Cornell University, Drexel University, Taiwan, Singapore, Japan) found that while titanium diselenide at room temperature has no chirality to it, as its temperature decreases it reaches a critical point where the balance of right-handed and left-handed electronic configurations gets thrown off and one type begins to dominate. They found that this effect could be controlled and enhanced by shining […]
When coronavirus is not alone: Team of complexity scientists present ‘meme’ model for multiple diseases
Phys.org February 24, 2020 From ‘fake news’ to innovative technologies, many contagions spread as complex contagions via a process of social reinforcement, where multiple exposures are distinct from prolonged exposure to a single source. Contrarily, biological agents such as Ebola or measles are typically thought to spread as simple contagions. An international team of researchers (USA -University of Vermont, Northeastern University, Canada) demonstrates that these different spreading mechanisms can have indistinguishable population-level dynamics once multiple contagions interact. In the social context, their results highlight the challenge of identifying and quantifying spreading mechanisms, such as social reinforcement, in a world where […]