Artículos con la etiqueta ‘superconductividad’

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%.

Remarks on the first hundred years of superconductivity

Por • 28 nov, 2011 • Category: Educacion

On the occasion of centenary of superconductivity discovery I recall some facts from the first period and attempts to understand the phenomenon. It turns out that most famous physicists of the first half of XX century have tried to solve the puzzle. Bardeen, Cooper and Schrieffer succeeded in 1957. The BCS theory successfully described all known facts and offered new predictions, which soon have been confirmed experimentally contributing to the widespread acceptance of the theory. It have found applications in nuclear physics, theory of neutron stars and cold atomic gases. The discoveries of new superconductors in the last thirty years show that simple BCS model is not enough to understand new unconventional superconductors. The studies of superconductors develop vividly and still fascinate new generations of physicists working in such diverse fields as material science and string theory.

Black holes: a model for superconductors?

Por • 5 mar, 2011 • Category: Crítica

“The context of this problem is high-temperature superconductivity,” said Phillips. “One of the great unsolved problems in physics is the origin of superconductivity (a conducting state with zero resistance) in the copper oxide ceramics discovered in 1986.” The results of research by Phillips and his colleagues Robert G. Leigh, Mohammad Edalati, and Ka Wai Lo were published online in Physical Review Letters on March 1 and in Physical Review D on February 25.