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 […]
Tag Archives: Quantum science
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
Physicists implement a version of Maxwell’s famous thought experiment for reducing entropy
Phys.org September 8, 2018 Reduced entropy in a three-dimensional lattice of super-cooled, laser-trapped atoms could help speed progress toward creating quantum computers. Researchers at Pennsylvania State University rearranged a randomly distributed array of atoms into neatly organized blocks, thus performing the function of a “Maxwell’s demon”—a thought experiment from the 1870s that challenged the second law of thermodynamics. The organized blocks of atoms could form the basis for a quantum computer that uses uncharged atoms to encode data and perform calculations… read more. TECHNICAL ARTICLE
Quantum optical neural networks
Arxiv August 29, 2018 A team of researchers in the US (MIT, industry partners) has shown that many of the features of neural networks for machine learning can naturally be mapped into the quantum optical domain by introducing the quantum optical neural network (QONN). Through numerical simulation and analysis, they trained the QONN to perform a range of quantum information processing tasks, including newly developed protocols for quantum optical state compression, reinforcement learning, and black-box quantum simulation. The results indicate QONNs are a powerful design tool for quantum optical systems and a promising architecture for next generation quantum processors… read […]
Scientists ‘teleport’ a quantum gate
Science Daily September 5, 2018 Modularity is used in constructing a large-scale quantum processor because of the errors and noise that are inherent in real-world quantum systems. An essential tool for universal quantum computation is the teleportation of an entangling quantum gate. Researchers at Yale University demonstrated the teleportation of a controlled-NOT (CNOT) gate, took a crucial step towards implementing robust, error-correctable modules by enacting the gate between two logical qubits, encoding quantum information redundantly. By using such an error-correctable encoding, their teleported gate achieves a process fidelity of 79 per cent. Teleported gates have implications for fault-tolerant quantum computation, […]
Quantum bugs, meet your new swatter
Science Daily August 20, 2018 According to a team of researchers in the US (Rice University, University of Maryland, industry, UT Austin) when a quantum computer executes an algorithm, it starts at a specific state. The state at the very end is the answer to the algorithm’s question. Reassembling the full state from these measurements, one can later pinpoint hardware or software errors that may have caused the computer to deliver unexpected results. However, the computational cost of reconstruction can be high even as few as five or six qubits. The team solved the validation problem with an algorithm they […]
Quantum chains in graphene nanoribbons
Science Daily August 9, 2018 Graphene nano-ribbons have very different electronic properties depending on their shape and width: conductor, semiconductor or insulator. An international team of researchers (Switzerland, China, Germany, USA -Rensselaer Polytechnic Institute) has succeeded in precisely adjusting the properties of the ribbons by specifically varying their shape. They were able to show that if these ribbons are built with regularly alternating zones of different widths, a chain of interlinked quantum states with its own electronic structure is created by the numerous transitions. The semiconducting nanoribbons would allow transistors with a channel cross-section 1,000 times smaller than typically manufactured […]
Another step forward on universal quantum computer
Phys.org August 13, 2018 Researchers in Japan have demonstrated non-adiabatic and non-abelian holonomic quantum gates over a geometric spin qubit on an electron or nitrogen nucleus, which paves the way to realizing a universal quantum computer. To avoid unwanted interference, they used a degenerate subspace of the triplet spin qutrit to form an ideal logical qubit in an NV center. This method facilitated fast and precise geometric gates at a temperature below 10 K, and the gate fidelity was limited by radiative relaxation. Based on this method, in combination with polarized microwaves, they succeeded in the manipulation of the geometric […]
Magnetic antiparticles offer new horizons for information technologies
Eurekalert August 15, 2018 An international team of researchers (Germany, Sweden, France, Czech Republic) theoretically explored the dynamics of skyrmions and antiskyrmions in ultrathin ferromagnetic films and showed that current-induced spin–orbit torques can lead to trochoidal motion and skyrmion–antiskyrmion pair generation, which occurs only for either the skyrmion or antiskyrmion, depending on the symmetry of the underlying Dzyaloshinskii–Moriya interaction. They developed algorithms which predict how spin–orbit torques can control the type of motion and the possibility to generate skyrmion lattices by antiskyrmion seeding. By increasing the amount of energy transferred to the system from the applied currents, they found that […]
Uncovering the interplay between two famous quantum effects
Phys.org July 23, 2018 According to some physicists the next scientific breakthroughs could lie in the interplay between Casimir force and superconductivity. Researchers in the Netherlands developed a sensor that consists of a microchip on which two strings are placed in close proximity. The wires can be cooled down to cryogenic temperatures, making them superconducting. The strings have holes in the centre that act as an optical resonator trapping laser light of a certain wavelength. They used this light to measure small displacements between the two wires, in essence it is possible to measure the forces that are acting upon […]