Phys.org December 17, 2018 An international team of researchers (USA – MIT, University of Hartford, UK. France) found that several materials with poor nonlinear characteristics can be combined, resulting in a new metamaterial that can be “tuned” to change the color of light. The enhancement comes from the way the metamaterial reshapes the flow of photons. They describe the underlying physics, compare its predictions to the experimental results, and analyze the limits of its applicability. The work opens a new direction in controlling the nonlinear response of materials and may find applications in on-chip optical circuits, drastically improving on-chip communications…read […]
Tag Archives: Quantum computing
Imperfections make photons perfect for quantum computing
Nanowerk December 17, 2018 Researchers at Rice University found that in molybdenum disulfide a dash of rhenium in just the right spot makes a configuration of atoms with energy states that sit comfortably inside and are isolated from the material’s natural band gap. Aligning magnetic moments of atoms in the defect and exciting them with light brings them to a higher energetic state making them exit as single photon. The direction of the photon is not understood, but the researchers suspect that it is well defined. The defect’s optical transition lies in the optical fiber telecommunication band, which is ideal […]
Senate bill would direct DOD to create a quantum computing consortium
Fed Scoop June 8, 2018 The consortium would be a partnership of various defense, federal, industry and academic research entities selected by the chief of the Office of Naval Research in the eastern half of the nation and the director of the Army Research Laboratory in the western half. Those two would oversee the consortium with the assistant director for quantum information science at the White House Office of Science and Technology Policy and other experts. The board would award grants, facilitate partnerships and assist in quantum information science research within the group… read more.
Light could make semiconductor computers a million times faster or even go quantum
Phys.org May 10, 2018 An international team of researchers (Germany, USA – University of Michigan) has demonstrated that a single layer of tungsten and selenium in a honeycomb lattice produces a pair of electron states known as pseudospins that can encode the 1 and 0. They prodded electrons into these states with quick pulses of infrared light. The initial pulse has its own spin, known as circular polarization, that sends electrons into one pseudospin state. Pulses of light that don’t have a spin can push the electrons from one pseudospin to the other—and back again. The work opens the door […]
Scaling silicon quantum photonic technology
Physorg March 9, 2018 An international team of researchers (UK, China, Denmark, Germany, Poland, Spain) has demonstrated a programmable path-encoded multidimensional entangled system with dimension up to 15×15, where two photons exist over 15 optical paths at the same time and are entangled with each other. This multidimensional entanglement is realised by exploiting silicon-photonics quantum circuits, integrating in a single chip, 550 optical components, including 16 identical photon-pair sources, 93 optical phase-shifters, 122 beam-splitters. The research provides a clear path to scaling up to the many millions of components that are ultimately needed for large-scale quantum computing applications… read more. […]
Approximate quantum cloning: The new way of eavesdropping in quantum cryptography
Physorg February 20, 2018 Uncertainty at the quantum scale makes exact cloning of quantum states impossible. Yet, they may be copied in an approximate way using probabilistic quantum cloning. Continuing previous work, researchers in China showed that if an independent subset cannot be expressed as the superposition of the other states in the set, then these dependent states can be partially cloned. Cloning operation allows scientists to make many copies of the output of computations—which take the form of unitary operations. These can, in turn, be used as input and fed into various further processes. Cloning also has applications in […]
Major discovery in controlling quantum states of single atoms
Science Daily February 16, 2018 To protect the quantum properties of a spin, control over its local environment, including energy relaxation and decoherence processes, is crucial. An international team of researchers (South Korea, USA – industry, Germany, Switzerland, Portugal, Spain) was able to precisely image individual iron atoms and measure and control the time that the iron atom can maintain its quantum behavior. They showed that the loss in quantum state superposition is mainly caused by nearby electrons that the researchers injected with extreme control into the iron atom. Understanding these destructive interactions allows us to avoid them in future […]
Controlling quantum interactions in a single material
Science Daily February 5, 2018 Using computational simulations, an international team of researchers (USA – Northwestern University, Austria, Germany, China) discovered coexisting quantum-mechanical interactions in the compound silver-bismuth-oxide. Bismuth enables the spin of the electron to interact with its own motion and does not exhibit inversion symmetry. By applying an electric field to the material, researchers were able to control whether the electron spins were coupled in pairs or separated as well as whether the system is electrically conductive or not. The findings could enable ultrafast, low-power electronics and quantum computers that operate faster than current models… read more. Open Access […]
Job One for Quantum Computers: Boost Artificial Intelligence
Quanta Magazine January 29, 2018 The fusion of quantum computing and machine learning has become a booming research area. Can it possibly live up to its high expectations? Although one might think a quantum machine-learning system should be powerful, it suffers from a kind of locked-in syndrome. It operates on quantum states, not on human-readable data, and translating between the two can negate its apparent advantages… read more.
Single-photon detector can count to 4
Source: Nanowerk December 15,2017 A team of researchers in the US (Duke University, Ohio State University, industry) used the superconducting nanowire single-photon detector (SNSPD) method to show multi-photon detection indicating number resolution up to four photons. They paid special attention to the specific shape of the initial spike in the electrical signal to correctly count at least four photons traveling together in a packet. Photon-number-resolution is very useful for a lot of quantum information/communication and quantum optics experiment; it could greatly increase the speed of quantum encryption techniques… read more. Open Access TECHNICAL ARTICLE