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Electron spin coherence of shallow donors in germanium

The magnetic moment, or spin, of an electron which is bound to an impurity atom in silicon is exceptionally coherent -- an important feature for its use as a quantum bit (qubit) in a quantum computer. However, those electrons are not easily controlled by electric fields. Electron spins in germanium are over 10,000 times more sensitive to an electric field, but it was not known if they would have long coherence.

An international collaboration led by Princeton University IRG3 researchers have measured electron spin coherence in germanium for the first time.1 The new data show that these electron spins can have coherence times of 1 ms, and the evidence points to even longer coherence at lower temperatures. These results suggest that germanium is a good material for electron spin quibits.

1. A. Sigillito, et al., Phys. Rev. Lett. 115, 247601 (2015).