Phys.org January 24, 2020 While Hilbert spaces with higher dimensionality it requires custom multimode fiber and limited by decoherence-induced mode coupling. An international team of researchers (China, South Africa) circumvented this by transporting multidimensional entangled states down conventional single-mode fiber (SMF). By entangling the spin-orbit degrees of freedom of a biphoton pair, passing the polarization (spin) photon down the SMF while accessing multiple orbital angular momentum (orbital) subspaces with the other, they realized multidimensional entanglement transport. They demonstrated transfer of multi-dimensional entanglement states over 250 m of single-mode fiber, showing that an infinite number of two-dimensional subspaces could be realized. […]
Tag Archives: Communications technology
Physicists find ways to overcome signal loss in magnonic circuits
Nanowerk January 2, 2020 Researchers in Russia analytically investigated properties of magnetostatic surface spin wave propagation in irregular narrow ferromagnetic waveguides that are important elements of magnonic logic. They demonstrated that the confinement effect in the narrow waveguide leads to multimode regime propagation, wave beats, and energy redistribution. These processes can be controlled by tuning the structure and excitation parameters. A gradual change in the waveguide width can be used to vary the spin wave energy density. Our results show that the impact of the width effect and the irregularity of the waveguide on the spin wave propagation are crucial. […]
In surprise breakthrough, scientists create quantum states in everyday electronics
Phys.org December 9, 2019 An international team of researchers (USA – University of Chicago, Argonne National Laboratory, Chicago, Japan, Sweden, Hungary) has demonstrated they could electrically control quantum states embedded in silicon carbide. The quantum states in silicon carbide have the added benefit of emitting single particles of light with a wavelength near the telecommunications band which makes them well suited to long-distance transmission through the same fiber-optic network. They found that by using the diode, a one-way switch for electrons the quantum signal suddenly became free of noise and was almost perfectly stable mitigating the impurity issue. The work […]
Researchers create better light-trapping devices
Phys.org November 18, 2019 Optical resonators’ performance is often limited by out-of-plane-scattering losses caused by inevitable fabrication imperfections. An international team of researchers (China, USA – MIT, University of Pennsylvania) proposed and experimentally demonstrated a class of guided resonances in photonic crystal slabs, in which out-of-plane-scattering losses are strongly suppressed by their topological nature. These resonances arise when multiple bound states in the continuum, merge in momentum space and enhance the quality factors Q of all nearby resonances in the same band. Using such resonances in the telecommunication regime, they experimentally achieved quality factor 10 times greater than other devices […]
Structured light promises path to faster, more secure communications
Science Daily October 29, 2019 Researchers in South Africa review the recent progress in the emergence of a second quantum revolution ushering in control of quantum states, outlining the core concepts in a tutorial manner before delving into the advances made in creation, manipulation, and detection of such quantum states. They cover advances in using orbital angular momentum as well as vectoral states that are hybrid entangled, combining spatial modes with polarization to form an infinite set of two-dimensional spaces: multidimensional entanglement. The authors highlight the work in pushing the boundaries in both the dimension and the photon number, before […]
New topological insulator reroutes photonic ‘traffic’ on the fly
Phys.org September 13, 2019 An international team of researchers (USA – University of Pennsylvania, Italy) has developed a prototype photonic chip that is roughly 250 microns square and features a tessellated grid of oval rings. By pumping the chip with an external laser, targeted to alter the photonic properties of individual rings, they are able to alter which of those rings constitute the boundaries of a waveguide. The result is a reconfigurable topological insulator. By changing the pumping patterns, photons headed in different directions can be routed around each other, allowing photons from multiple data packets to travel through the […]
Electrical engineers develop ‘beyond 5G’ wireless transceiver
Science Daily July 12, 2019 An international team of researchers (USA – UC Irvine, France) fabricated a single-channel 115-135-GHz receiver prototype in a 55-nm SiGe BiCMOS which has max conversion gain of 32 dB and a min noise figure of 10.3 dB. They measured a data rate of 36 Gb/s at 30-cm distance with the received 8PSK signal being directly demodulated on-chip at a bit-error rate of 1e-6. The prototype occupies 2.5 x 3.5 mm² of die area, including PADs and test circuit and consumes a total dc power of 200.25 mW…read more. TECHNICAL ARTICLE
Physicists’ finding could revolutionize information transmission
Phys.org July 9, 2019 An international team of researchers (USA – UC Riverside, National High Magnetic Field Laboratory, State University of Florida, Japan) has observed, characterized, and controlled dark trions in tungsten diselenide. Because a trion contains three interacting particles, controllable spin and momentum indices and a rich internal structure, it can carry much more information than a single electron. The lifetime of dark trions is more than 100 times longer than the more common bright trions. The long lifetime enables information transmission by trions over a much longer distance. They demonstrated continuous tuning from positive dark trions to negative […]
Drone transmits uncompressed 4K video in real time using millimeter wave tech
Phys.org July 1, 2019 Millimeter wave wireless communication is expected to be used in 5G because of the high-speed communication, but the problem is that communication distance is limited due to large attenuation of radio waves. An international team of researchers (Japan, USA – industry) has developed a video transmission system with a millimeter wave wireless communication device that uses a small, lightweight lens antenna that can be mounted on a drone. In tests, the team was able to use a drone to take video in 4K and transmit the video in real time from over 100 m in the […]
‘Tsunami’ on a silicon chip: A world first for light waves
Science Daily July 3, 2019 An international team of researchers (Singapore, Australia) has shown CMOS‐compatible, on‐chip Bragg solitons, with a soliton‐effect pulse compression with a factor of × 5.7, along with time‐resolved measurements of soliton fission on a CMOS‐compatible photonic circuit platform. These observations are enabled by the combination of a unique cladding‐modulated Bragg grating design and the high nonlinearity and negligible nonlinear loss of compositionally engineered ultra‐silicon‐rich nitride (USRN: Si7N3). Manipulating solitons on-chip could potentially allow for the speed up of photonic communications devices and infrastructure…read more. TECHNICAL ARTICLE