Shiyao Zhu

Synthesizing five-body interaction in a superconducting quantum circuit

  1. Ke Zhang,
  2. Hekang Li,
  3. Pengfei Zhang,
  4. Jiale Yuan,
  5. Jinyan Chen,
  6. Wenhui Ren,
  7. Zhen Wang,
  8. Chao Song,
  9. Da-Wei Wang,
  10. H. Wang,
  11. Shiyao Zhu,
  12. Girish S. Agarwal,
  13. and Marlan O. Scully
Synthesizing many-body interaction Hamiltonian is a central task in quantum simulation. However, it is challenging to synthesize interactions including more than two spins. Borrowing
tools from quantum optics, we synthesize five-body spin-exchange interaction in a superconducting quantum circuit by simultaneously exciting four independent qubits with time-energy correlated photon quadruples generated from a qudit. During the dynamic evolution of the five-body interaction, a Greenberger-Horne-Zeilinger state is generated in a single step with fidelity estimated to be 0.685. We compare the influence of noise on the three-, four- and five-body interaction as a step toward answering the question on the quantum origin of chiral molecules. We also demonstrate a many-body Mach-Zehnder interferometer which potentially has a Heisenberg-limit sensitivity. This study paves a way for quantum simulation involving many-body interactions and high excited states of quantum circuits.
arxiv pdf

Observation of multi-component atomic Schrödinger cat states of up to 20 qubits

  1. Chao Song,
  2. Kai Xu,
  3. Hekang Li,
  4. Yuran Zhang,
  5. Xu Zhang,
  6. Wuxin Liu,
  7. Qiujiang Guo,
  8. Zhen Wang,
  9. Wenhui Ren,
  10. Jie Hao,
  11. Hui Feng,
  12. Heng Fan,
  13. Dongning Zheng,
  14. Dawei Wang,
  15. H. Wang,
  16. and Shiyao Zhu
We report on deterministic generation of 18-qubit genuinely entangled Greenberger-Horne-Zeilinger (GHZ) state and multi-component atomic Schrödinger cat states of up to 20 qubits on
a quantum processor, which features 20 superconducting qubits interconnected by a bus resonator. By engineering a one-axis twisting Hamiltonian enabled by the resonator-mediated interactions, the system of qubits initialized coherently evolves to an over-squeezed, non-Gaussian regime, where atomic Schrödinger cat states, i.e., superpositions of atomic coherent states including GHZ state, appear at specific time intervals in excellent agreement with theory. With high controllability, we are able to take snapshots of the dynamics by plotting quasidistribution Q-functions of the 20-qubit atomic cat states, and globally characterize the 18-qubit GHZ state which yields a fidelity of 0.525±0.005 confirming genuine eighteen-partite entanglement. Our results demonstrate the largest entanglement controllably created so far in solid state architectures, and the process of generating and detecting multipartite entanglement may promise applications in practical quantum metrology, quantum information processing and quantum computation.
arxiv pdf

Parallel quantum operations with chiral spin states in a superconducting circuit

  1. Da-Wei Wang,
  2. Chao Song,
  3. Wei Feng,
  4. Han Cai,
  5. Da Xu,
  6. Hui Deng,
  7. Dongning Zheng,
  8. Xiaobo Zhu,
  9. H. Wang,
  10. Shiyao Zhu,
  11. and Marlan O. Scully
Recently it was shown that mesoscopic superpositions of photonic states can be prepared based on a spin-gated chiral photon rotation in a Fock-state lattice of three cavities coupled
to a spin (two-level atom). By exchanging the roles of the cavities and the spin, we have performed parallel operations on chiral spin states based on an antisymmetric spin exchange interaction (ASI) in a superconducting circuit. The ASI, which is also called Dzyaloshinskii-Moriya interaction, plays an important role in the formation of topological spin textures such as skyrmions. By periodically modulating the transition frequencies of three superconducting qubits interacting with a bus resonator, we synthesize a chiral ASI Hamiltonian with spin-gated chiral dynamics, which allow us to demonstrate a three-spin chiral logic gate and entangle up to five qubits in Greenberger-Horne-Zeilinger states. Our results pave the way for quantum simulation of magnetism with ASI and quantum computation with chiral spin states.
arxiv pdf