title: An all-optical quantum gate in a semiconductor quantum dot.
abstract: We report coherent optical control of a biexciton (two electron-hole pairs), confined in a single quantum dot, that shows coherent oscillations similar to the excited-state Rabi flopping in an isolated atom. The pulse control of the biexciton dynamics, combined with previously demonstrated control of the single-exciton Rabi rotation, serves as the physical basis for a two-bit conditional quantum logic gate. The truth table of the gate shows the features of an all-optical quantum gate with interacting yet distinguishable excitons as qubits. Evaluation of the fidelity yields a value of 0.7 for the gate operation. Such experimental capability is essential to a scheme for scalable quantum computation by means of the optical control of spin qubits in dots.
authors.affiliation: Frontiers in Optical Coherent and Ultrafast Science (FOCUS), Harrison M. Randall Laboratory of Physics, The University of Michigan, Ann Arbor, Michigan 48109-1120, USA.
authors.forename: Xiaoqin
authors.initials: X
authors.lastname: Li
authors.forename: Yanwen
authors.initials: Y
authors.lastname: Wu
authors.forename: Duncan
authors.initials: D
authors.lastname: Steel
authors.forename: D
authors.initials: D
authors.lastname: Gammon
authors.forename: T H
authors.initials: TH
authors.lastname: Stievater
authors.forename: D S
authors.initials: DS
authors.lastname: Katzer
authors.forename: D
authors.initials: D
authors.lastname: Park
authors.forename: C
authors.initials: C
authors.lastname: Piermarocchi
authors.forename: L J
authors.initials: LJ
authors.lastname: Sham