Coupled quantum dots as quantum gates

被引:1345
作者
Burkard, G
Loss, D
DiVincenzo, DP
机构
[1] Univ Basel, Dept Phys & Astron, CH-4056 Basel, Switzerland
[2] IBM Corp, Thomas J Watson Res Ctr, Div Res, Yorktown Heights, NY 10598 USA
来源
PHYSICAL REVIEW B | 1999年 / 59卷 / 03期
关键词
D O I
10.1103/PhysRevB.59.2070
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
We consider a quantum-gate mechanism based on electron spins in coupled semiconductor quantum dots. Such gates provide a general source of spin entanglement and can be used for quantum computers. We determine the exchange coupling J in the effective Heisenberg model as a function of magnetic (B) and electric fields, and of the interdot distance a within the Heitler-London approximation of molecular physics. This result is refined by using sp hybridization, and by the Hund-Mulliken molecular-orbit approach, which leads to an extended Hubbard description for the two-dot system that shows a remarkable dependence on B and a due to the long-range Coulomb interaction. We find that the exchange J changes sign at a finite field (leading to a pronounced jump in the magnetization) and then decays exponentially. The magnetization and the spin susceptibilities of the coupled dots are calculated. We show that the dephasing due to nuclear spins in GaAs can be strongly suppressed by dynamical nuclear-spin polarization and/or by magnetic fields. [S0163-1829(99)01003-6].
引用
收藏
页码:2070 / 2078
页数:9
相关论文
共 42 条
[1]  
[Anonymous], SPRINGER SERIES SOLI
[2]   Electrons in artificial atoms [J].
Ashoori, RC .
NATURE, 1996, 379 (6564) :413-419
[3]   Adiabatic quantum computation with Cooper pairs [J].
Averin, DV .
SOLID STATE COMMUNICATIONS, 1998, 105 (10) :659-664
[4]   CONDITIONAL QUANTUM DYNAMICS AND LOGIC GATES [J].
BARENCO, A ;
DEUTSCH, D ;
EKERT, A ;
JOZSA, R .
PHYSICAL REVIEW LETTERS, 1995, 74 (20) :4083-4086
[5]   ELEMENTARY GATES FOR QUANTUM COMPUTATION [J].
BARENCO, A ;
BENNETT, CH ;
CLEVE, R ;
DIVINCENZO, DP ;
MARGOLUS, N ;
SHOR, P ;
SLEATOR, T ;
SMOLIN, JA ;
WEINFURTER, H .
PHYSICAL REVIEW A, 1995, 52 (05) :3457-3467
[6]   Complex broadband millimeter wave response of a double quantum dot: Rabi oscillations in an artificial molecule [J].
Blick, RH ;
van der Weide, DW ;
Haug, RJ ;
Eberl, K .
PHYSICAL REVIEW LETTERS, 1998, 81 (03) :689-692
[7]   Formation of a coherent mode in a double quantum dot [J].
Blick, RH ;
Pfannkuche, D ;
Haug, RJ ;
von Klitzing, K ;
Eberl, K .
PHYSICAL REVIEW LETTERS, 1998, 80 (18) :4032-4035
[8]   Coupled quantum dots as quantum exclusive-OR gate [J].
Brum, JA ;
Hawrylak, P .
SUPERLATTICES AND MICROSTRUCTURES, 1997, 22 (03) :431-436
[9]  
BURKARD G, UNPUB
[10]   Experimental implementation of fast quantum searching [J].
Chuang, IL ;
Gershenfeld, N ;
Kubinec, M .
PHYSICAL REVIEW LETTERS, 1998, 80 (15) :3408-3411