Phys.org October 30, 2018 An international team of researchers (Australia, the Netherlands, Japan, USA – industry) has demonstrated an integrated device platform incorporating a silicon metal-oxide-semiconductor double quantum dot that is capable of single-spin addressing and control via electron spin resonance, combined with high-fidelity spin readout in the singlet-triplet basis. They have shown that they can combine this with a special type of quantum readout process known as Pauli spin blockade, a key requirement for quantum error correcting codes that will be necessary to ensure accuracy in large spin-based quantum computers. The new integrated design can be manufactured using well-established […]
Tag Archives: Quantum science
Quantum predictions
Phys.org November 2, 2018 To more fully understand and harness properties of complex materials such as vanadium dioxide a team of researchers in the US (Oak Ridge National Laboratory, Argonne National Laboratory, Sandia National Laboratories, Lawrence Livermore National Laboratory, the University of California, Berkeley, North Carolina State University) is using the Quantum Monte Carlo method which accounts for the individual behavior of all of the electrons without major approximations, reducing systematic errors in simulations and producing reliable results. The team has built open-source software, known as QMCPACK, that is now available online and on all the DOE Office of Science […]
Entangled Photons Sneak through Hole Unscathed
American Physical Society Focus October 26, 2018 An international team of researchers (Austria, Australia, Spain, Italy) has demonstrated that quantum entanglement can be symmetry protected in the interaction with a single subwavelength plasmonic nanoaperture. By using specially engineered two-photon states to match the properties of the nanoaperture they demonstrated that two-photon entanglement can be either completely preserved or completely lost after the interaction with the nanoaperture, solely depending on the relative phase between the quantum states. The work should help in finding ways to keep delicate quantum information from being destroyed in future nanoscale chips… read more. TECHNICAL ARTICLE
Shielded quantum bits
Phys.org October 26, 2018 An international team of researchers (USA – Princeton University, Germany) proposes a quadrupolar exchange-only spin qubit that is highly robust against charge noise and nuclear spin dephasing, the dominant decoherence mechanisms in quantum dots. The qubit consists of four electrons trapped in three quantum dots and operates in a decoherence-free subspace to mitigate dephasing due to nuclear spins. Because of on-site exchange mediated by the Coulomb interaction, the qubit energy splitting is electrically controllable and can amount to several GHz even in the “off” configuration, making it compatible with conventional microwave cavities. The new method makes […]
QuTech researchers put forward a roadmap for quantum internet development
Delft University of Technology (the Netherlands) October 18, 2018 Researchers in the Netherlands describe six phases, starting with simple networks of qubits that could already enable secure quantum communications – a phase that could be reality in the near future. The development ends with networks of fully quantum-connected quantum computers. In each phase, new applications become available such as extremely accurate clock synchronization or integrating different telescopes on Earth in one virtual ‘supertelescope’. This work creates a common language that unites the highly interdisciplinary field of quantum networking towards achieving the dream of a world-wide quantum internet… read more. TECHNICAL […]
Large family of quantum spin liquids revealed
Physics World October 18, 2018 Researchers in China synthesized and characterized a large family of rare-earth chalcogenides AReCh 2 (A = alkali or monovalent ions, Re = rare earth, Ch = O, S, Se) which share the same structure (Rbar 3m) as YbMgGaO 4 , and antiferromagnetically coupled rare-earth ions form perfect triangular layers that are well separated along the c-axis. The family, having the simplest structure and chemical formula among the known QSL candidates, removes the issue on possible exchange disorders in YbMgGaO 4 . The rich diversity of the family members allows tunable charge gaps, variable exchange coupling, […]
Research on light-matter interaction could improve electronic and optoelectronic devices
Eurekalert October 10, 2018 To study low dimensional quantum materials and their quantum effects an international team of researchers (USA – Rensselaer Polytechnic Institute, Florida State University, UC Berkeley, Japan) built a device by stacking multiple atomically thin materials together, including graphene, boron nitride and tungsten diselenide. They showed that as the density of the exciton increases, more electrons and holes pair together, forming four-particle and even five-particle excitonic complexes. They revealed the true biexciton state, a unique four-particle complex responding to light and the nature of the charged biexciton, a five-particle complex. The research gives rise to fundamental understanding […]
Measurement-device-independent quantum communication without encryption
Phys.org October 11, 2018 The key problem of practical quantum secure direct communication (QSDC) is that apparatuses used in practical quantum communication systems have some defects, and these imperfections, especially defects in the measurement devices, can lead to leakage of information and affect the security of practical QSDC. Researchers in China proposed a measurement-and-device-independent quantum secure direct communication protocol using Einstein-Podolsky-Rosen pairs. This protocol eliminates all loopholes related to measurement devices, which solves a key obstacle in practical quantum secure direct communication. The protocol has also an extended communication distance, and a high communication capacity…read more. TECHNICAL ARTICLE
Quantum technologies can be applied on a standard telecommunications network
Phys.org October 4, 2018 Researchers in Spain have developed a quantum cryptography network integrated in a commercial optical network through technologies based on software defined networking allowing for the implementation of quantum and classical network services in a flexible, dynamic and scalable manner. The technology has been developed on an existing infrastructure using standard communications systems and allows switching between links connecting points that may be up to 60 kilometers apart. Twenty channels can share the same fiber in the same optical band that uses the quantum channel, allowing the simultaneous transmission of quantum signals with more than two terabytes […]
Researchers find ferrimagnets could be used to speed up spintronics devices
Phys.org September 25, 2018 For spintronics devices research focused on ferromagnetic materials to stabilize small spin textures and to move them efficiently with high velocities, but ferromagnets show fundamental limits for speed and size. An international team of researchers (USA- MIT, Germany) circumvent these limits using compensated ferrimagnets. Using ferrimagnetic Pt/Gd44Co56/TaOx films they realized a current-driven domain wall motion with a speed of 1.3 km s–1. Both the size and dynamics of the ferrimagnet are in excellent agreement with a simplified effective ferromagnet theory. The research shows using ferrimagnets instead of ferromagnets could theoretically speed up spintronics devices… read more. TECHNICAL ARTICLE