Microwave spectroscopy of a quantum-dot molecule

被引:529
作者
Oosterkamp, TH
Fujisawa, T
van der Wiel, WG
Ishibashi, K
Hijman, RV
Tarucha, S
Kouwenhoven, LP
机构
[1] Delft Univ Technol, Dept Appl Phys, NL-2600 GA Delft, Netherlands
[2] Delft Univ Technol, DIMES, NL-2600 GA Delft, Netherlands
[3] NTT, Basic Res Labs, Atsugi, Kanagawa 2430198, Japan
[4] RIKEN, Inst Phys & Chem Res, Wako, Saitama 35101, Japan
关键词
D O I
10.1038/27617
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
Quantum dots are small conductive regions in a semiconductor, containing a variable number of electrons (from one to a thousand) that occupy well-defined, discrete quantum states-for which reason they are often referred to as artificial atoms(1). Connecting them to current and voltage contacts allows the discrete energy spectra to be probed by charge-transport measurements. Two quantum dots can be connected to form an 'artificial molecule'. Depending on the strength of the inter-dot coupling (which supports quantum-mechanical tunnelling of electrons between the dots), the two dots can form 'ionic' (refs 2-6) or 'covalent' bonds. In the former case, the electrons are localized on individual dots, while in the latter, the electrons are delocalized over both dots. The covalent binding leads to bonding and antibonding states, whose energy difference is proportional to the degree of tunnelling. Here we report a transition from ionic bonding to covalent bonding in a quantum-dot 'artificial molecule' that is probed by microwave excitations(5-8). Our results demonstrate controllable quantum coherence in single-electron devices, an essential requirement for practical applications of quantum-dot circuitry.
引用
收藏
页码:873 / 876
页数:4
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