Zhang-Qi Yin

Observation of topological magnon insulator states in a superconducting circuit

  1. Weizhou Cai,
  2. Jiaxiu Han,
  3. Feng Mei,
  4. Yuan Xu,
  5. Yuwei Ma,
  6. Xuegang Li,
  7. Haiyan Wang,
  8. Yipu Song,
  9. Zheng-Yuan Xue,
  10. Zhang-qi Yin,
  11. Suotang Jia,
  12. and Luyan Sun
Searching topological states of matter in tunable artificial systems has recently become a rapidly growing field of research. Meanwhile, significant experimental progresses on observing
topological phenomena have been made in superconducting circuits. However, topological insulator states have not yet been reported in this system. Here, for the first time, we experimentally realize a spin version of the Su-Schrieffer-Heeger model and observe the topological magnon insulator states in a superconducting qubit chain, which manifest both topological invariants and topological edge states. Based on simply monitoring the time evolution of a singlequbit excitation in the chain, we demonstrate that the topological winding numbers and the topological magnon edge and soliton states can all be directly observed. Our work thus opens a new avenue to use controllable qubit chain system to explore novel topological states of matter and also offers exciting possibilities for topologically protected quantum information processing.
arxiv pdf

Perfect remote quantum state transfer in a superconducting qubit chain with parametrically tunable couplings

  1. X. Li,
  2. Y. Ma,
  3. J. Han,
  4. Tao Chen,
  5. Y. Xu,
  6. W. Cai,
  7. H. Wang,
  8. Y. P. Song,
  9. Zheng-Yuan Xue,
  10. Zhang-qi Yin,
  11. and Luyan Sun
Faithfully transferring quantum state is essential for quantum information processing. Here, we demonstrate a fast (in 84~ns) and high-fidelity (99.2%) quantum state transfer in a
chain of four superconducting qubits with nearest-neighbor coupling. This transfer relies on full control of the effective couplings between neighboring qubits, which is realized only by parametrically modulating the qubits without increasing circuit complexity. Once the couplings between qubits fulfill specific ratio, a perfect quantum state transfer can be achieved in a single step, therefore robust to noise and accumulation of experimental errors. This quantum state transfer can be extended to a larger qubit chain and thus adds a desirable tool for future quantum information processing. The demonstrated flexibility of the coupling tunability is suitable for quantum simulation of many-body physics which requires different configurations of qubit couplings.
arxiv pdf

Quantum non-demolition measurement of single phonon state with nitrogen-vacancy centers ensemble and superconducting qubit

  1. Rui-xia Wang,
  2. Kang Cai,
  3. Zhang-qi Yin,
  4. and Gui-lu Long
We propose a scheme to realize the quantum non-demolition single phonon detection and emission based on the interaction between the NV ensemble and the superconducting flux qubit. The
resonant frequency of the flux qubit will change with the NVE absorbing a single phonon, then we can detect the single phonon state through measuring the frequency shift of the flux qubit. The fidelity of the absorbing process can reach a much high value. After the detection process, the NVE can emit the absorbed phonon as we apply a driving pulse which is in reverse to the absorbing process. The overlap between the input and the output phonon shapes can reach 98.57%. The scheme can be realized under the realistic experimental condition.
arxiv pdf

Quantum network of superconducting qubits through opto-mechanical interface

  1. Zhang-qi Yin,
  2. W. L. Yang,
  3. L. Sun,
  4. and L. M. Duan
We propose a scheme to realize quantum networking of superconducting qubits based on the opto-mechanical interface. The superconducting qubits interact with the microwave photons, which
then couple to the optical photons through the opto-mechanical interface. The interface generates a quantum link between superconducting qubits and optical flying qubits with tunable pulse shapes and carrier frequencies, enabling transmission of quantum information to other superconducting or atomic qubits. We show that the scheme works under realistic experimental conditions and it also provides a way for fast initialization of the superconducting qubits under 1 K instead of 20 mK operation temperature.
arxiv pdf

Resonator-Assisted Quantum Bath Engineering of a Flux Qubit

  1. Xian-Peng Zhang,
  2. Li-Tuo Shen,
  3. Zhang-Qi Yin,
  4. Huai-Zhi Wu,
  5. and Zhen-Biao Yang
We demonstrate quantum bath engineering for preparation of any orbital state with controllable phase factor of a superconducting flux qubit assisted by a microwave coplanar waveguide
resonator. We have investigated the polarization efficiency of the arbitrary direction of the pseudo angular momentum space, and obtained an effective Rabi frequency by using the convergence condition of Markovian master equation. The processes of polarization can be implemented effectively in a dissipative environment created by resonator photon decay when the spectrum of the microwave resonator matches with the specially tailored Rabi and resonant frequencies of the drive. Our calculations indicate that state-preparation fidelities in excess of 99.9\% and the required time on the order of magnitude of microsecond are in principle possible for experimentally reasonable sample parameters. Furthermore, our proposal is available to generalize to any other kinds of spin-based qubits.
arxiv pdf