Controllable freezing of the nuclear spin bath in a single-atom spin qubit
Mateusz T Madzik, Thaddeus D Ladd, Fay E Hudson, Kohei M Itoh, Alexander M Jakob, Brett C Johnson, Jeffrey C McCallum, David N Jamieson, Andrew S Dzurak, Arne Laucht, Andrea Morello
Science Advances | AMER ASSOC ADVANCEMENT SCIENCE | Published : 2020
The quantum coherence and gate fidelity of electron spin qubits in semiconductors are often limited by nuclear spin fluctuations. Enrichment of spin-zero isotopes in silicon markedly improves the dephasing time T*2, which, unexpectedly, can extend two orders of magnitude beyond theoretical expectations. Using a single-atom 31P qubit in enriched 28Si, we show that the abnormally long T*2 is due to the freezing of the dynamics of the residual 29Si nuclei, caused by the electron-nuclear hyperfine interaction. Inserting a waiting period when the electron is controllably removed unfreezes the nuclear dynamics and restores the ergodic T*2 value. Our conclusions are supported by a nearly parameter-..View full abstract
Awarded by Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology
Awarded by U.S. Army Research Office
The research was funded by the Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology (grant no. CE170100012) and the U.S. Army Research Office (contract nos. W911NF-17-1-0200 and W911NF-17-1-0198). We acknowledge support from the Australian National Fabrication Facility (ANFF) and the AFAiiR node of the NCRIS Heavy Ion Capability for access to ion-implantation facilities. K.M.I. acknowledges support from a Grant-in-Aid for Scientific Research by MEXT. T.D.L. acknowledges support from the Gordon Godfrey Bequest Sabbatical grant. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the ARO or the U.S. Government.