Optics and Photonics July 6, 2018 An international team of researchers (USA – Princeton University, Gemological Institute of America, UK) reports a color center that shows insensitivity to environmental decoherence caused by phonons and electric field noise: the neutral charge state of silicon vacancy (SiV0). Through careful materials engineering, they achieved >80% conversion of implanted silicon to SiV0. SiV0 exhibits spin-lattice relaxation times approaching 1 minute and coherence times approaching 1 second. Its optical properties are very favorable, with ~90% of its emission into the zero-phonon line and near–transform-limited optical linewidths. These combined properties make SiV0 a promising defect for […]
Tag Archives: Quantum science
Quantum-enhanced sensing of magnetic fields
Science Daily July 2, 2018 Transmon qubit is currently one of the leading candidates for a building block of large-scale quantum computers. An international team of researchers (Finland, Switzerland, Russia) has constructed an artificial atom with an intrinsic magnetic moment that is around 100’000 times larger than that of natural atoms or ions. The coupling of large moment to an external magnetic field makes it possible to accurately measure the strength of the field. The combination of harnessing quantum hardware and quantum algorithms in the context of quantum sensing provides an appealing route towards novel devices that, ultimately, promise to […]
Spatial overlap leads to useful quantum entanglement, say physicists
Physics World June 25, 2018 Researchers in Italy studied independently prepared identical particles showing that, when they spatially overlap, an operational entanglement exists that can be made to manifest by means of separated localized measurements. They proved this entanglement is physical as it can be directly exploited to activate quantum information protocols, such as teleportation. These results establish that particle indistinguishability is a utilizable quantum feature and open the way to new quantum-enhanced applications… read more. TECHNICAL ARTICLE
Silicon carbide LEDs make bright single photon sources
Physics World June 18, 2018 An international team of researchers (Germany, Japan, Sweden, South Korea) has discovered a variety of new colour centres in lateral p-i-n diodes made from a polytype (a crystal structure) of silicon carbide called 4H-SiC that contains naturally occurring divacancies. The newly-discovered centres emit non-classical light in the visible and near-infrared range. One type of defect can even be excited using electrical means. This means that it might be integrated into compact electronics devices as there would be no need for an additional bulky laser system to optically excite it. The work opens new directions both […]
A surprising twist on skyrmions
Phys.org June 12, 2018 An international team of researchers (UK, China, Germany) measured the helicity angle of surface skyrmions, providing direct experimental evidence that a twisted skyrmion surface state also exists in bulk systems. The exact surface helicity angles of twisted skyrmions for both left- and right-handed chiral bulk Cu2OSeO3, in the single as well as in the multidomain skyrmion lattice state, are determined, revealing their detailed internal structure. The findings suggest that a skyrmion surface reconstruction is a universal phenomenon, stemming from the breaking of translational symmetry at the interface. The study suggests the importance of free surfaces has […]
The right squeeze for quantum computing
Phys.org June 01, 2018 Inherent properties of photons in light are used for encoding information as quantum bits into a light beam by digitizing patterns of the electromagnetic field. “Squeezing” light is used to reduce errors from light waves during quantum computation. Researchers in Japan have developed a theoretical model that uses both the properties of quantum bits and the modes of the electromagnetic field in which they exist. The approach involves squeezing light by removing error-prone quantum bits when quantum bits cluster together. According to the researchers this model is 10 billion times more tolerant to errors than current […]
Time crystals may hold secret to coherence in quantum computing
Science Daily May 29, 2018 A time crystal is a structure that does not repeat in space, like normal three-dimensional crystals such as snowflakes or diamonds, but in time. In practice this means that crystals constantly undergo spontaneous change, breaking the symmetry of time by achieving a self-sustaining oscillation. An international team of researchers (Finland, UK, Russia) has demonstrated quasi-crystals by studying the Bose-Einstein condensation of magnons in superfluid Helium-3. They observed the time quasicrystal and its transition to a superfluid time crystal… read more. TECHNICAL ARTICLE
Deeper understanding of quantum chaos may be the key to quantum computers
Phys.org May 14, 2018 An international team of researchers (UK, Austria, Switzerland) has provided a theoretical explanation for the robust oscillations that kept the atoms in a quantum state for an extended time as predicted by Harvard University and MIT. The team’s work suggests that these oscillations are due to a new physical phenomenon that called ‘quantum many-body scar’. Previous theories involving quantum scars have been formulated for a single particle. The work extends these ideas to systems which contain not one but many particles, which are all entangled with each other in complicated ways. Quantum many-body scars might represent […]
Nationwide program launches to train new generation of quantum engineers
Eurekalert May 9, 2018 Funded by a $1.6 million award from the National Science Foundation, the Institute for Molecular Engineering at the University of Chicago and Harvard University will head a new nationwide graduate student training program for quantum science and engineering. The program, Quantum Information Science and Engineering Network, will group select graduate students with both an academic adviser and one from a leading technology company or national laboratory. Over the course of four years, the “triplets” will each address a pressing research question for both academia and industry. Approximately 20 students will receive four years of funding under […]
Picking one photon out of the flow
Science Daily May 3, 2018 An international team of researchers (Denmark, Germany, USA – NIST) has implemented photonic memory. The general idea was to first store an optical field, and then send another one through the medium. Photons in the second beam take notice of the stored photons and interact with them in such a way that exactly one photon is tagged and later discarded on retrieval. Being robbed of a single photon, the original light beam is left in a peculiar quantum state that has numerous scientific and technological applications. This method paves the way towards future quantum communication […]