共查询到6条相似文献,搜索用时 0 毫秒
1.
Li X Wu Y Steel D Gammon D Stievater TH Katzer DS Park D Piermarocchi C Sham LJ 《Science (New York, N.Y.)》2003,301(5634):809-811
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. 相似文献
2.
Berezovsky J Mikkelsen MH Gywat O Stoltz NG Coldren LA Awschalom DD 《Science (New York, N.Y.)》2006,314(5807):1916-1920
Kerr rotation measurements on a single electron spin confined in a charge-tunable semiconductor quantum dot demonstrate a means to directly probe the spin off-resonance, thus minimally disturbing the system. Energy-resolved magneto-optical spectra reveal information about the optically oriented spin polarization and the transverse spin lifetime of the electron as a function of the charging of the dot. These results represent progress toward the manipulation and coupling of single spins and photons for quantum information processing. 相似文献
3.
Berezovsky J Mikkelsen MH Stoltz NG Coldren LA Awschalom DD 《Science (New York, N.Y.)》2008,320(5874):349-352
Most schemes for quantum information processing require fast single-qubit operations. For spin-based qubits, this involves performing arbitrary coherent rotations of the spin state on time scales much faster than the spin coherence time. By applying off-resonant, picosecond-scale optical pulses, we demonstrated the coherent rotation of a single electron spin through arbitrary angles up to pi radians. We directly observed this spin manipulation using time-resolved Kerr rotation spectroscopy and found that the results are well described by a model that includes the electronnuclear spin interaction. Measurements of the spin rotation as a function of laser detuning and intensity confirmed that the optical Stark effect is the operative mechanism. 相似文献
4.
We observe spin blockade due to Pauli exclusion in the tunneling characteristics of a coupled quantum dot system when two same-spin electrons occupy the lowest energy state in each dot. Spin blockade only occurs in one bias direction when there is asymmetry in the electron population of the two dots, leading to current rectification. We induce the collapse of the spin blockade by applying a magnetic field to open up a new spin-triplet current-carrying channel. 相似文献
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