Nanowerk October 13, 2020 In nonlinear crystals, two photons of a particular frequency can be turned into one photon having twice that frequency if they are phase matched. This often severely limits practical applications. Researchers in Switzerland combined resonances and disorder by implementing random quasi-phase-matching in Mie resonant spheres of a few micrometres realized by the bottom-up assembly of barium titanate nanocrystals. The measured second-harmonic generation reveals a combination of broadband and resonant wave mixing, in which Mie resonances drive and enhance the second-harmonic generation, while the disorder keeps the phase-matching conditions relaxed. The nanocrystal assemblies provide new opportunities for […]
Tag Archives: S&T Switzerland
Ultrafast electrons in magnetic oxides: A new direction for spintronics?
Science Daily August 19, 2020 Special metal oxides could one day replace semiconductor materials that are commonly used today in processors. Until recently it had not been clear how the electron transfer across the band gap coupled with the spin of the magnetic oxide occurs. An international team of researchers (Germany, USA – research institute, Switzerland) was able to excite an electron to lift it across the band gap in nickel oxide. They also observed how the information was then transferred to the magnetic system. This enabled the team to identify a previously unknown ultrafast coupling mechanism that occurs on […]
Deep learning and metamaterials make the invisible visible
Nanowerk August 11, 2020 Due to the diffraction limit seeing and recognizing an object whose size is much smaller than the illumination wavelength is a challenging task for an observer placed in the far field. Researchers in Switzerland have demonstrated that combining deep learning with lossy metalenses allows recognizing and imaging largely subwavelength features directly from the far field. Their acoustic learning experiment shows that, despite being 30 times smaller than the wavelength of sound, the fine details of images can be successfully reconstructed and recognized in the far field, which is crucially favored by the presence of absorption. They […]
A new path for electron optics in solid-state systems
Science Daily July 14, 2020 Electron optics has been demonstrated mainly in one-dimensional devices, for example in nanotubes. Researchers in Switzerland have shown that the band inversion and hybridization present in two coupled semiconductor layers, consisting of InAs and GaSb system provide a novel transport mechanism that guarantees non-vanishing interference even when all angles of incidence occur. Through a combination of transport measurements and theoretical modelling, they found that their devices operate as a Fabry-Pérot interferometer in which electrons and holes form hybrid states. As the mechanism requires only band inversion and hybridization, the research opens engineering electron-optical phenomena in […]
Using magnetic worms to engineer nanoscale communication systems
Nanowerk July 15, 2020 High-frequency electromagnetic waves are used to transmit and process information in microelectronic devices. To gain a better understanding of precisely the way magnons behave and propagate in different structures researchers in Switzerland examined how electromagnetic waves propagate, and how they could be manipulated, in artificial ferromagnetic quasicrystals. They found that under controlled conditions a single electromagnetic wave coupled to an artificial quasicrystal splits into several spin waves which then propagate within the structure. Each of these spin waves represents a different phase of the original electromagnetic wave, carrying different information. By imaging wavefronts in quasicrystals, insight […]
Adding noise for completely secure communication
Science Daily June 11, 2020 Device-independent quantum key distribution provides security even when the equipment used to communicate over the quantum channel is largely uncharacterized. A central obstacle in photonic implementations is that the global detection efficiency, i.e., the probability that the signals sent over the quantum channel are successfully received, must be above a certain threshold. Researchers in Switzerland developed a protocol that adds artificial noise, which cannot be known or controlled by an adversary, to the initial measurement data (the raw key). Focusing on a realistic photonic setup using a source based on spontaneous parametric down conversion, they […]
Combining magnetic data storage and logic
Phys.org June 16, 2020 Researchers in Switzerland built racetrack memory managed to perform logical operations directly within memory element. The racetrack memory elements work by using current pulses to move tiny magnetic domains up and down nanowires that are just a few hundred nanometres thick. In these domains, all the magnetic moments are oriented in the same direction and can thus be used to represent the binary states 0 and 1. They use an electric current to reverse the polarity of the magnetic regions, thereby performing a NOT operation on the stored data. By eliminating the need for the mechanical […]
The smallest motor in the world
Science Daily June 16, 2020 Researchers in Switzerland have developed a molecular motor which consists of only 16 atoms and rotates reliably in one direction. It could allow energy harvesting at the atomic level. The special feature of the motor is that it moves exactly at the boundary between classical motion and quantum tunneling — and has revealed puzzling phenomena to researchers in the quantum realm…read more. TECHNICAL ARTICLE
Surprisingly strong and deformable silicon
EurekAlert June 10, 2020 Silicon is very brittle which can become a problem when trying to make MEMS from silicon, such as the acceleration sensors in smartphones. Researchers in Switzerland have demonstrated that Si processed by modern lithography procedures exhibits an ultrahigh elastic strain limit, near ideal strength (shear strength ~4 GPa) and plastic deformation at the micron-scale, one order of magnitude larger than samples made using focused ion beams, due to superior surface quality. This extended elastic regime enables enhanced functional properties by allowing higher elastic strains to modify the band structure. Further, the micron-scale plasticity of Si allows the investigation […]
Photonic microwave generation using on-chip optical frequency combs
Science Daily April 20, 2020 Soliton microcombs can now be built using CMOS-compatible photonic integrated circuits. However, they operate with repetition rates significantly beyond those that conventional electronics can detect, preventing their use in microwave photonics. Researchers in Switzerland have demonstrated soliton microcombs operating in two widely employed microwave bands, the X-band (~10 GHz, for radar) and the K-band (~20 GHz, for 5G). Driven by a low noise fibre laser, these devices produce more than 300 frequency lines within the 3 dB bandwidth, and generate microwave signals with phase noise levels comparable to modern electronic microwave oscillators. The results establish integrated microcombs as […]