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DATE | 2013-10-07 |

TIME | 11:30 |

PLACE | R313, 3F, NCTS, NCKU |

FIELD | Quantum Information Science |

SPEAKER | Prof. Amnon Aharony - Department of Physics, Ben-Gurion University and Tel Aviv University, Israel(以色列科學院院士、美國科學藝術院外籍院士、歐洲科學藝術及人文院院士及挪威皇家科學院院士) |

TITLE | Retrieving qubit information despite decoherence |

ABSTRACT | A major aim of quantum computing is to store and maintain quantum information on qubits (two level quantum systems). Information is usually fully lost after long times, by decoherence caused by the coupling of the qubit to its environment. We consider a qubit consisting of two single-level quantum dots, connected via two tunneling paths, with an Aharonov-Bohm flux enclosed between them. The environment is modeled by telegraph noise. Tuning gate voltages, we show that one can reach special situations, in which the reduced density matrix of the qubit maintains information on the initial quantum state even at very long times. This initial information can be identified by measuring the circulating current around the loop and/or the occupations of the qubit dots. Generalizations to other geometries will also be discussed |