PerspectiveApplied Physics

Coherent Holes in a Semiconductor Quantum Dot

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Science  03 Jul 2009:
Vol. 325, Issue 5936, pp. 42-43
DOI: 10.1126/science.1176296

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Building a quantum computer requires finding a system with long-lived coherence—one in which the wave function of a quantum state maintains its phase over time. In solid-state implementations of quantum information processing, coherent states can be generated with electron spins, and semiconductor quantum dots are powerful platforms for preparing, controlling, and measuring electron spin coherence (1). However, interactions between the electron spin and its environment destroy the fragile coherence (2) and lead to a loss of information. On page 70 of this issue, Brunner et al. (3) address this problem by using “holes”—positive charge carriers that result from unfilled states in an electronic band. They demonstrate that one measure of coherence, the inhomogeneous dephasing time of the hole spin, is at least an order of magnitude longer than that for electron spins.