Li-Na Ji

Path-optimized nonadiabatic geometric quantum computation on superconducting qubits

  1. Cheng-Yun Ding,
  2. Li-Na Ji,
  3. Tao Chen,
  4. and Zheng-Yuan Xue
Quantum computation based on nonadiabatic geometric phases has attracted a broad range of interests, due to its fast manipulation and inherent noise resistance. However, to obtain universal
geometric quantum gates, the required evolution paths are usually limited to some special ones, and the evolution times of which are still longer than dynamical quantum gates, resulting in weakening of robustness and more infidelity of the implemented geometric gates. Here, we propose a path-optimized scheme for geometric quantum computation on superconducting transmon qubits, where high-fidelity and robust universal nonadiabatic geometric gates can be implemented, based on conventional experimental setups. Specifically, we find that, by selecting appropriate evolution paths, the constructed geometric gates can be superior to their corresponding dynamical ones under different local errors. Through our numerical simulations, we obtain the fidelities for single-qubit geometric Phase, π/8 and Hadamard gates as 99.93%, 99.95% and 99.95%, respectively. Remarkably, the fidelity for two-qubit control-phase gate can be as high as 99.87%. Therefore, our scheme provides a new perspective for geometric quantum computation, making it more promising in the application of large-scale fault-tolerant quantum computation.
arxiv pdf

Scalable nonadiabatic holonomic quantum computation on a superconducting qubit lattice

  1. Li-Na Ji,
  2. Tao Chen,
  3. and Zheng-Yuan Xue
Geometric phase is an indispensable element for achieving robust and high-fidelity quantum gates due to its built-in noise-resilience feature. However, due to the complexity of manipulation
and the intrinsic leakage of the encoded quantum information to non-logical-qubit basis, the experimental realization of universal nonadiabatic holonomic quantum computation is very difficult. Here, we propose to implement scalable nonadiabatic holonomic quantum computation with decoherence-free subspace encoding on a two-dimensional square superconducting transmon-qubit lattice, where only the two-body interaction of neighbouring qubits, from the simplest capacitive coupling, is needed. Meanwhile, we introduce qubit-frequency driving to achieve tunable resonant coupling for the neighbouring transmon qubits, and thus avoiding the leakage problem. In addition, our presented numerical simulation shows that high-fidelity quantum gates can be obtained, verifying the advantages of the robustness and scalability of our scheme. Therefore, our scheme provides a promising way towards the physical implementation of robust and scalable quantum computation.
arxiv pdf