Josephson Diode

Diode is a fundamental building block of modern electronics for controlling the normal electric current. It is based on the p-n junction of semiconductors which only allows current to flow from the p-side to the n-side. For superconductors, there also exist electron-doped and hole-doped versions. What will happen we put the electron and hole-doped superconductors together and make the depletion region as a Mott-insulator? We (with Jiangping Hu and Xi Dai) performed a preliminary study on this problem Ref. [1] .

Control supercurrent

The Josephson effect is one of the most fundamental effects associated with the superconducting phase, regardless of differences among various superconducting materials. We investigate a new design of the Josephson junction by taking advantage of the competition between the superconducting and Mott-insulating phases. The two sides of the junction are hole and electron-doped superconductors, respectively, which are close to the superconductor-Mott-insulator transition, and this setup is dubbled "Josephson diode". At the interface, a self-organized Mott-insulating region is formed as the tunneling barrier. Similarly to the conventional p-n junctions in semiconductor diodes, the depletion region is suppressed by a positive bias voltage and elongated by a negative bias voltage, giving rise to an asymmetric response of the Josephson current to the external voltage. The depletion region not only plays a role of tunneling barrier, but also its quantum fluctuation reveals important information of strong correlation effects. The fluctuation of the region boundaries couples to the carrier recombination process which results in an additional phase dynamics that can be measured experimentally in the noise spectrum of the Josephson junction.

References and talks

  • 1. Jiang-ping Hu, Congjun Wu, and Xi Dai, "Proposed Design of a Josephson Diode", , Phys. Rev. Lett. 99, 067004 (2007) , see pdf file .

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    Last modified: July 15, 2007.