Chenxu Liu


Title: Theoretical investigation of Photon Manipulation for Quantum Computing and Quantum information Processing

Abstract: Quantum computing and quantum information processing are fast developing fields. As more and more qubits are integrated into the quantum computing systems, a deeper understanding and more careful modeling of the dynamics of these quantum systems in presence of driving and/or loss are necessary, not only for optimizing existing quantum devices, but also for designing and achieving novel method for more precise manipulation of these quantum systems. Our work investigating these quantum systems is inspired by quantum optics, a field focused on the quantum description of light and light-matter interactions.

In this thesis, we use the theoretical toolboxes provided by quantum optics as well as condensed matter theory to investigate and model realistic quantum systems. Specifically, we focus on the Nitrogen-vacancy centers in diamond crystal, a Josephson parametric amplifier (that uses Josephson junctions as its non-linear elements), and plasmonic nanowire system. With the knowledge of the dynamics of these systems, we proposed single-photon heralded two-NV center quantum gates; designed and optimized the superconducting circuit for a Josephson parametric amplifier to improve the amplifier's saturation power; and designed new methods for robust light manipulation using topologically protected plasmonic modes. All the devices that we study are either ready to be implemented in experiments or have already been built. Further, as discussed in this thesis, our theoretical analysis of NV-centers can be extended to similar device types like solid-state defect centers, while our analysis of Josephson parametric amplifiers can be extended to other types of superconducting circuit systems.


  1. “Optimizing Josephson-Ring-Modulator-based Josephson Parametric Amplifiers viafull Hamiltonian control”, Chenxu Liu, Tzu-Chiao Chien, Michael Hatridge, David Pekker, in preparation
  2. "Multiparametric Amplification and Qubit Measurement with a Kerr-free Josephson Ring Modulator," T-C Chien, O Lanes, C Liu, X Cao, P Lu, S Motz, G Liu, D Pekker, M Hatridge, arXiv:1903.02102
  3. "Single-photon heralded 2-qubit unitary gates for pairs of nitrogen-vacancy centers in diamond," Chenxu Liu, M.V. Gurudev Dutt and David Pekker, Phys. Rev. A, 98, 052342
  4. "Robust manipulation of light using topologically protected plasmonic modes," Chenxu Liu, M.V. Gurudev Dutt, and David Pekker, Optical Express, 26 (3), 2857-2872
  5. "Effect of edge rounding on the extinction properties of hollow metal nanoparticles," Jun Qian, Chen-xu Liu, Wu-deng Wang, Jing Chen, Yu-dong Li, Jing-jun Xu, Qian Sun, Plasmonics, 8 (2), 955-962



Graduate Advisor

David Pekker