P. Z. Zhao

Experimental realization of nonadiabatic geometric gates with a superconducting Xmon qubit

  1. P. Z. Zhao,
  2. Zhangjingzi Dong,
  3. Zhenxing Zhang,
  4. Guoping Guo,
  5. D.M. Tong,
  6. and Yi Yin
Geometric phases are only dependent on evolution paths but independent of evolution details so that they own some intrinsic noise-resilience features. Based on different geometric phases,
various quantum gates have been proposed, such as nonadiabatic geometric gates based on nonadiabatic Abelian geometric phases and nonadiabatic holonomic gates based on nonadiabatic non-Abelian geometric phases. Up to now, nonadiabatic holonomic one-qubit gates have been experimentally demonstrated with the supercondunting transmon, where three lowest levels with cascaded configuration are all applied in the operation. However, the second excited states of transmons have relatively short coherence time, which results in a lessened fidelity of quantum gates. Here, we experimentally realize Abelian-geometric-phase-based nonadiabatic geometric one-qubit gates with a superconducting Xmon qubit. The realization is performed on two lowest levels of an Xmon qubit and thus avoids the influence from the short coherence time of the second excited state. The experimental result indicates that the average fidelities of single-qubit gates can be up to 99.6% and 99.7% characterized by quantum process tomography and randomized benchmarking, respectively.
arxiv pdf

Single-shot realization of nonadiabatic holonomic gates with a superconducting Xmon qutrit

  1. Zhenxing Zhang,
  2. P. Z. Zhao,
  3. Tenghui Wang,
  4. Liang Xiang,
  5. Zhilong Jia,
  6. Peng Duan,
  7. D.M. Tong,
  8. Yi Yin,
  9. and Guoping Guo
Nonadiabatic holonomic quantum computation has received increasing attention due to its robustness against control errors as well as high-speed realization. The original protocol of
nonadiabatic holonomic one-qubit gates has been experimentally demonstrated with superconducting transmon qutrit. However, the original protocol requires two noncommuting gates to realize an arbitrary one-qubit gate, which doubles the exposure time of gates to error sources and therefore makes the gates vulnerable to environment-induced decoherence. Single-shot protocol was subsequently proposed to realize an arbitrary one-qubit nonadiabatic holonomic gate. In this paper, we experimentally realize the single-shot protocol of nonadiabatic holonomic single qubit gates with a superconducting Xmon qutrit, where all the Clifford element gates are realized by a single-shot implementation. Characterized by quantum process tomography and randomized benchmarking, the single-shot gates reach a fidelity larger than 99%.
arxiv pdf