Artículos con la etiqueta ‘Mesoscale and Nanoscale Physics (cond-mat.mes-hall);’

Logic gates at the surface code threshold: Superconducting qubits poised for fault-tolerant quantum computing

Por • 6 mar, 2014 • Category: Leyes

A quantum computer can solve hard problems – such as prime factoring, database searching, and quantum simulation – at the cost of needing to protect fragile quantum states from error. Quantum error correction provides this protection, by distributing a logical state among many physical qubits via quantum entanglement. Superconductivity is an appealing platform, as it allows for constructing large quantum circuits, and is compatible with microfabrication. For superconducting qubits the surface code is a natural choice for error correction, as it uses only nearest-neighbour coupling and rapidly-cycled entangling gates. The gate fidelity requirements are modest: The per-step fidelity threshold is only about 99%. Here, we demonstrate a universal set of logic gates in a superconducting multi-qubit processor, achieving an average single-qubit gate fidelity of 99.92% and a two-qubit gate fidelity up to 99.4%.



Self-assembling hybrid diamond-biological quantum devices

Por • 18 sep, 2013 • Category: Ciencia y tecnología

The realization of scalable arrangements of nitrogen vacancy (NV) centers in diamond remains a key challenge on the way towards efficient quantum information processing, quantum simulation and quantum sensing applications. Although technologies based on implanting NV-center in bulk diamond crystals or hybrid device approaches have been developed, they are limited in the achievable spatial resolution and by the intricate technological complexities involved in achieving scalability. We propose and demonstrate a novel approach for creating an arrangement of NV-centers, based on the self-assembling capabilities of biological systems and its beneficial nanometer spatial resolution. Here, a self-assembled protein structure serves as a structural scaffold for surface functionalized nanodiamonds, in this way allowing for the controlled creation of NV-structures on the nanoscale and providing a new avenue towards bridging the bio-nano interface.



Metallic bonds become molecular-like in atomic-sized devices

Por • 2 jun, 2013 • Category: Educacion

One of the defining characteristics of metals is the way they are held together. Essentially, a lattice of metal ions sits in a sea of delocalised electrons and this acts as a kind of glue that binds the structure together. These “metallic bonds” are entirely different from the covalent bonds that hold molecules together. For a start, metallic bonds are a collective phenomenon that come about because of the bulk behaviour of metal ions and delocalised electrons. But what of the bond that holds together the simplest metal structure imaginable–two metal atoms forming a bridge? Today, Harsh Deep Chopra and pals at The State University of New York at Buffalo say they have characterised the nature of this bond at room temperature for the first time. That could have important implications for the way atomic scale devices are designed and built. “The directional bonds provide high configurational stability to atomic-sized metallic devices,” say Chopra and co.