Feng-Lei Gu

Simulation of topological nodal-loop bands on a superconducting circuits chain

  1. Feng-Lei Gu,
  2. Dan-Wei Zhang,
  3. and Zheng-Yuan Xue
Nodal-loop semimetal is one of the exotic gapless topological states of matter that are discovered recently. Here we propose an experimentally feasible scheme to simulate the three-dimensional
topological nodal-loop semimetal bands in a one-dimensional circuit quantum electrodynamics lattice, by introducing two additional parameter dimensions. A unit-cell of the lattice consists of a transmissionline resonator coupled by a superconducting transmon qubit, and two of the dressed states in a unit-cell are used to simulate the spin-1/2 states of an electron. The neighboring transmission-line resonators are connected by a superconducting quantum interference device, and the effective hopping among them is induced by parametric coupling. Meanwhile, the two artificial dimensions are simulated by tunable Zeeman terms of the spins. The detection of the mimic nodal-loop bands is also discussed and is shown to be well within current technology. Therefore, our scheme provides a feasible way to explore nodal-loop semimetal bands and other topological bands of different spin-orbit coupling forms in this controllable artificial system.
arxiv pdf

Nonadiabatic Holonomic Quantum Computation with Dressed-state Qubits

  1. Zheng-Yuan Xue,
  2. Feng-Lei Gu,
  3. Zhuo-Ping Hong,
  4. Zi-He Yang,
  5. Dan-Wei Zhang,
  6. Yong Hu,
  7. and J. Q. You
Implementing holonomic quantum computation is a challenging task as it requires complicated interaction among multilevel systems. Here, we propose to implement nonadiabatic holonomic
quantum computation based on dressed-state qubits in circuit QED. An arbitrary holonomic single-qubit gate can be conveniently achieved using external microwave fields and tuning their amplitudes and phases. Meanwhile, nontrivial two-qubit gates can be implemented in a coupled cavities scenario assisted by a grounding SQUID with tunable interaction, where the tuning is achieved by modulating the ac flux threaded through the SQUID. In addition, our proposal is directly scalable, up to a two-dimensional lattice configuration. In our scheme, the dressed states only involve the lowest two levels of each transmon qubits and the effective interactions exploited are all of resonant nature. Therefore, we release the main difficulties for physical implementation of holonomic quantum computation on superconducting circuits.
arxiv pdf