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Quantum computing: 50-year-old prediction confirmed

Jülich, 17 April 2014 – Scientists at Yale have improved the energy storage time of a superconducting quantum switch by several orders of magnitude. Together with Jülich physicist Dr. Gianluigi Catelani the scientists confirmed a 50-year-old, previously untested theoretical prediction in physics. The team reports its results in the April 17 issue of the journal Nature.

The phenomenon of superconductivity is not only applied to build the powerful electromagnets that are used in MRI/NMR machines and particle accelerators, it also lays the ground for high-quality quantum switches that are essential for the development of quantum computers — an innovation that would offer vastly greater information processing power and speed than classical (digital) computers.

In the Yale experiment, researchers demonstrated that a type of superconducting quantum bit can be immune to dissipation caused by quasiparticles, microscopic entities that can drain the energy of the qubit. Superconducting quantum bits, or qubits, are artificial atoms that store information in quantum systems. They also manipulate that information as they switch among states — such as "0" "1," or both simultaneously — under the influence of other qubits. But in switching states, they tend to lose energy. The resulting information loss is one of the biggest obstacles in the development of quantum hardware.

The experiment confirms by direct measurement a theoretical prediction made by Nobel Prize-winning British physicist Brian Josephson in the 1960s, namely that quasiparticle dissipation should vanish in a junction under certain conditions. Josephson junctions are superconducting devices with properties well suited for building quantum processing systems. Dr. Gianluigi Catelani from Jülich’s Peter Grünberg Institute (PGI-2) showed by theoretical analysis that the immunity to dissipation, arising from a quantum mechanical interference effect, applies also to qubits.

Rasterelektronenmikroskopische Aufnahme eines Josephson-KontaktsScanning electron micrograph of a Josephson junction, the basic building block of superconducting quantum circuits.
Source: I. Pop / Yale University

Original publication:

Coherent suppression of electromagnetic dissipation due to superconducting quasiparticles
Ioan M. Pop, Kurtis Geerlings, Gianluigi Catelani, Robert J. Schoelkopf, Leonid I. Glazman, & Michel H. Devoret
Nature, published on 17 April 2014, doi10.1038/nature13017
Article

Weitere Informationen:

Press release from Yale University
Peter Grünberg Institute, Theoretical Nanoelectronics (PGI-2 / IAS-3)

Contact:

Dr. Gianluigi Catelani, Peter Grünberg Institut,
Theoretical Nanoelectronics (PGI-2 / IAS-3)
phone: +49 2461 61-9360
g.catelani@fz-juelich.de

Press contact:

Tobias Schlößer
phone: +49 2461 61-4771
t.schloesser@fz-juelich.de


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