Exchange Coupling in a Linear Chain of Three Quantum-Dot Spin Qubits in Silicon

Kok Wai Chan, Harshad Sahasrabudhe, Wister Huang, Yu Wang, Henry C. Yang, Menno Veldhorst, Jason C.C. Hwang, Fahd A. Mohiyaddin, Fay E. Hudson, Kohei M. Itoh, Andre Saraiva, Andrea Morello, Arne Laucht, Rajib Rahman, Andrew S. Dzurak

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)


Quantum gates between spin qubits can be implemented leveraging the natural Heisenberg exchange interaction between two electrons in contact with each other. This interaction is controllable by electrically tailoring the overlap between electronic wave functions in quantum dot systems, as long as they occupy neighboring dots. An alternative route is the exploration of superexchange - the coupling between remote spins mediated by a third idle electron that bridges the distance between quantum dots. We experimentally demonstrate direct exchange coupling and provide evidence for second neighbor mediated superexchange in a linear array of three single-electron spin qubits in silicon, inferred from the electron spin resonance frequency spectra. We confirm theoretically, through atomistic modeling, that the device geometry only allows for sizable direct exchange coupling for neighboring dots, while next-nearest neighbor coupling cannot stem from the vanishingly small tail of the electronic wave function of the remote dots, and is only possible if mediated.

Original languageEnglish
Pages (from-to)1517-1522
Number of pages6
JournalNano Letters
Issue number3
Publication statusPublished - 2021 Feb 10


  • exchange interaction
  • qubit
  • silicon
  • superexchange

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering


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