Synopsis: Eliminating charge noise

A proposal for how to design a superconducting qubit solves the problem of decoherence caused by randomly charged impurities.
Synopsis figure
Illustration: J. Koch et al., Phys. Rev. Lett. (2009)

In a paper appearing in Physical Review Letters, Jens Koch, Vladimir Manucharyan, Michel Devoret, and Leonid Glazman from Yale University in the US find a correspondence between the Cooper-pair box and its inductively shunted partner. Despite the obvious change from a discrete to a continuous spectrum of the charge operator, the excitation spectra of the two systems are found to be closely related. In particular, charging effects are observable in the dynamical response function of the inductively shunted system, which exhibits distinct peaks at frequencies governed by the spectrum of the isolated Cooper-pair box. Therefore, addressing the inductance-shunted Cooper-pair box solely by ac voltages, i.e., microwave radiation, solves the problem of realizing a stable, charge-noise-free Cooper-pair-box artificial atom. These ideas form the basis for a new type of Josephson-junction device called the fluxonium (presented by the same authors in an experimental paper, see Ref. [1]) that consists of a small junction shunted with the large inductance from a series array of large-capacitance tunnel junctions. – Sarma Kancharla

[1] V. Manucharyan, Science 326, 113 (2009).

Correction (27 November 2009): Corrections were made to the first and last sentences of the first paragraph.


More Features »


More Announcements »

Subject Areas

Quantum InformationMesoscopicsNanophysics

Previous Synopsis

Fluid Dynamics

Collective action in dusty plasma

Read More »

Next Synopsis

Related Articles

Focus: Nanochannel Could Separate Mixed Fluids
Fluid Dynamics

Focus: Nanochannel Could Separate Mixed Fluids

Calculations show that capillary forces affecting a fluid mixture flowing through a nanochannel could be used to separate the mixture. Read More »

Focus: Negative Resistance with a Single Atom

Focus: Negative Resistance with a Single Atom

Current flowing through a single silicon atom can be made to decrease with increasing voltage, potentially allowing the integration of a new type of component into microelectronic circuits. Read More »

Viewpoint: Photon Qubit is Made of Two Colors

Viewpoint: Photon Qubit is Made of Two Colors

Single particles of light can be prepared in a quantum superposition of two different colors, an achievement that could prove useful for quantum information processing. Read More »

More Articles