### Abstract

Original language | English |
---|---|

Pages (from-to) | 667-670 |

Number of pages | 4 |

Journal | Nature |

Volume | 442 |

DOIs | |

Publication status | Published - 2006 |

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### Cite this

*Nature*,

*442*, 667-670. https://doi.org/10.1038/nature05018

}

*Nature*, vol. 442, pp. 667-670. https://doi.org/10.1038/nature05018

**Supercurrent reversal in quantum dots.** / Dam, Van, J.A.; Nazarov, Y.V.; Bakkers, E.P.A.M.; Franceschi, De, S.; Kouwenhoven, L.P.

Research output: Contribution to journal › Article › Academic › peer-review

TY - JOUR

T1 - Supercurrent reversal in quantum dots

AU - Dam, Van, J.A.

AU - Nazarov, Y.V.

AU - Bakkers, E.P.A.M.

AU - Franceschi, De, S.

AU - Kouwenhoven, L.P.

PY - 2006

Y1 - 2006

N2 - When two superconductors are electrically connected by a weak link - such as a tunnel barrier - a zero-resistance supercurrent can flow. This supercurrent is carried by Cooper pairs of electrons with a combined charge of twice the elementary charge, e. The 2e charge quantum is clearly visible in the height of voltage steps in Josephson junctions under microwave irradiation, and in the magnetic flux periodicity of h/2e (where h is Planck's constant) in superconducting quantum interference devices. Here we study supercurrents through a quantum dot created in a semiconductor nanowire by local electrostatic gating. Owing to strong Coulomb interaction, electrons only tunnel one-by-one through the discrete energy levels of the quantum dot. This nevertheless can yield a supercurrent when subsequent tunnel events are coherent. These quantum coherent tunnelling processes can result in either a positive or a negative supercurrent, that is, in a normal or a p-junction, respectively. We demonstrate that the supercurrent reverses sign by adding a single electron spin to the quantum dot. When excited states of the quantum dot are involved in transport, the supercurrent sign also depends on the character of the orbital wavefunctions. © 2006 Nature Publishing Group. U7 - Export Date: 2 August 2010 U7 - Source: Scopus

AB - When two superconductors are electrically connected by a weak link - such as a tunnel barrier - a zero-resistance supercurrent can flow. This supercurrent is carried by Cooper pairs of electrons with a combined charge of twice the elementary charge, e. The 2e charge quantum is clearly visible in the height of voltage steps in Josephson junctions under microwave irradiation, and in the magnetic flux periodicity of h/2e (where h is Planck's constant) in superconducting quantum interference devices. Here we study supercurrents through a quantum dot created in a semiconductor nanowire by local electrostatic gating. Owing to strong Coulomb interaction, electrons only tunnel one-by-one through the discrete energy levels of the quantum dot. This nevertheless can yield a supercurrent when subsequent tunnel events are coherent. These quantum coherent tunnelling processes can result in either a positive or a negative supercurrent, that is, in a normal or a p-junction, respectively. We demonstrate that the supercurrent reverses sign by adding a single electron spin to the quantum dot. When excited states of the quantum dot are involved in transport, the supercurrent sign also depends on the character of the orbital wavefunctions. © 2006 Nature Publishing Group. U7 - Export Date: 2 August 2010 U7 - Source: Scopus

U2 - 10.1038/nature05018

DO - 10.1038/nature05018

M3 - Article

C2 - 16900196

VL - 442

SP - 667

EP - 670

JO - Nature

JF - Nature

SN - 0028-0836

ER -