Phys.og June 29, 2021 The challenge in optical quantum information processing has been the realization of two-qubit gates for photonic qubits due to the lack of highly efficient optical Kerr nonlinearities at the single-photon level. A team of researchers in the US (Washington University, University of Michigan) found that a high-fidelity frequency-encoded deterministic two-photon controlled-phase gate can be achieved by exploiting the strong photon-photon correlation enabled by photonic dimers, and the unique nonreciprocal photonic propagation in chiral quantum nanophotonic systems. They are testing the design to show that it can operate under moderate conditions. According to the researchers so far […]
Tag Archives: Information processing
Controlling magnetization by surface acoustic waves
Nanowerk May 27, 2021 Interconversion between electron spin and other forms of angular momentum is useful for spin-based information processing. Well-studied examples of this are the conversion of photon angular momentum and rotation into ferromagnetic moment. Recently, several theoretical studies have suggested that the circular vibration of atoms work as phonon angular momentum; however, conversion between phonon angular momentum and spin-moment has yet to be demonstrated. Researchers in Japan demonstrated that the phonon angular momentum of surface acoustic wave can control the magnetization of a ferromagnetic Ni film by means of the phononic-to-electronic conversion of angular momentum in a Ni/LiNbO3 […]
Developing smarter, faster machine intelligence with light
Phys.org December 18, 2020 Optical alternatives to electronic hardware could help speed up machine learning processes by simplifying the way information is processed in a non-iterative way. However, photonic-based machine learning is typically limited by the number of components that can be placed on photonic integrated circuits, limiting the interconnectivity, while free-space spatial-light-modulators are restricted to slow programming speeds. A team of researchers in the US (George Washington University, UCLA, industry) replaced spatial light modulators with digital mirror-based technology, thus developing a system over 100 times faster. The non-iterative timing of this processor, in combination with rapid programmability and massive […]
Physics breakthrough of the year
EurekAlert December 17, 2020 Silicon crystallized in the usual cubic (diamond) lattice structure has dominated the electronics industry for more than half a century. However, cubic silicon, germanium and SiGe alloys are all indirect-bandgap semiconductors that cannot emit light efficiently. An international team of researchers (Canada, the Netherlands, Germany, Austria) has demonstrated efficient light emission from direct-bandgap hexagonal Ge and SiGe alloys. They measured a sub-nanosecond, temperature-insensitive radiative recombination lifetime and observed an emission yield similar to that of direct-bandgap group-III–V semiconductors. They demonstrated that, by controlling the composition of the hexagonal SiGe alloy, the emission wavelength can be continuously […]
Researchers discover a uniquely quantum effect in erasing information
EurekAlert October 16, 2020 Where computing protocols are concerned, finite-time processing in the quantum regime can dynamically generate coherence. An international team of researchers (UK, Ireland) has shown that this can have significant thermodynamic implications. They demonstrated that quantum coherence generated in the energy eigen basis of a system undergoing a finite-time information erasure protocol yields rare events with extreme dissipation. These fluctuations are of purely quantum origin. By studying the full statistics of the dissipated heat in the slow-driving limit, they proved that coherence provides a non-negative contribution to all statistical cumulants. Even a single bit erasure events yield […]