Welcome to Quantum Science Group

Our research group focuses on understanding quantum phenomena in engineered quantum systems and developing ways to make them useful for quantum technologies. Physical systems that we focus on include ion-traps, superconducting quantum circuits, and defects in solids. Our research interest lies at the interface of quantum information science, quantum optics, and condensed matter physics.

Open positions

  • We are looking for postdocs to join the Quantum Science Group at DKU! The candidate is expected to have expertise in one of the following areas: theory of open quantum systems, theoretical quantum optics, statistical physics, or quantum information/technology. If you are interested, please send your CV to Prof. Hwang.

News

  • (December, 2023) A new paper on cavity magnonics with easy-axis ferromagnet is published in Physical Review B as a letter. In this work, we identify that the anisotropy in a ferromagnetic material can be harnessed to generate a quantum squeezing of magnons and propose a cavity magnonic setup to probe such a quantum effect. This work is done in collaboration with our friends at POSTECH, South Korea, Jongjun Lee and Hyun-Woo Lee. Journal Ref.: J. M. Lee, H. -W. Lee, and M. -J. Hwang, Phys. Rev. B 108, L241404 (2023).

 

  • (October, 2023) Our work on “Anomalous criticality with bounded fluctuations and long-range frustration induced by broken time-reversal symmetry” is published as a Letter in Physical Review Research. Here we discover an anomalous superradiant phase transition induced by broken time-reversal symmetry in the Dicke lattice model. It gets the name anomalous since the fluctuation at the critical point is bounded! Journal Ref.: J. Zhao and M. -J. Hwang, Phys. Rev. Research 5, L042016 (2023).
  • (August, 2023) Our work on “Topological magnon-photon interaction for cavity magnonics” is published in Communications Physics. In this work, a result of fruitful collaboration with Prof. Hyun-Woo Lee’s group at POSTECH, we proposed a novel mechanism for the interaction between a collective quantum excitation in a magnet called magnon and a cavity photon using a topological insulator as a glue. This new mechanism, which we dubbed as “topological magnon-photon interaction”, gives rise to an order of magnitude larger coupling strength than an ordinary magnon-photon interaction, a feature that could be potentially useful for quantum technology based on cavity magnonics.
    Journal Ref.: J. M. Lee, M. -J. Hwang, and H. -W. Lee Communications Physics 6, 194 (2023).

  • (July, 2023) Myung-Joong gave an invited lecture on “Quantum Light and Matter” at the KIAS Quantum Information Workshop 2023 held at Korea Institute of Advanced Study in Seoul. In this lecture, aimed at graduate students and researchers working in quantum information, he introduced the physics of quantum light-matter interaction as operational principles of quantum information processing for superconducting and ion-trap quantum computers.
  • (June, 2023) We held a quantum science summer workshop at DKU. It was a wonderful opportunity for students at DKU to learn about research topics in quantum science group and also have hands-on experience using analytical and numerical tools.
  • (May, 2023) A new preprint titled “Cavity magnonics with easy-axis ferromagnet: critically enhanced magnon squeezing and light-matter interaction” uploaded to arXiv. This is a joint work with Jongjun M. Lee and Prof. Hyun-Woo Lee from POSTECH, South Korea.
  • (April, 2023) Our research on “Dynamical scaling laws in the quantum q-state clock chain” is published in Physical Review B. In this work, we study the critical dynamics and the dynamical phase transition of the quantum q-state clock chain using the Loschmidt echo as a common theoretical tool. Our work shows how the equilibrium critical exponents govern these non-equilibirum critical phenomena and also shows that the non-equilibrium critical dynamics of Berezinskii-Kosterlitz-Thouless (BKT) transition are fundamentally different from that of the second-order phase transition. Journal Ref: J.-C. Tang, W.-L. You, M.-J. Hwang, and G. Sun Physical Review B 107, 134303 (2023).

Figure 3

  • (January, 2023) A new preprint titled “Dynamical scaling laws in the quantum q-state clock chain” uploaded to arXiv. This is a joint work with Prof. Gaoyong Sun’s group in Nanjing.
  • (November, 2022) Dr. Guitao Lyu joins our group as a postdoctoral researcher. Dr. Lyu recently got his PhD from Zhejiang University and is an expert in the physics of cold atoms and exciton-polariton condensates. Welcome Guitao!
  • (November, 2022) Our postdoc Dr. Jonas Florinas is leaving our group to take up a professor position at Universidade federal da grande Dourados in Brazil. We are very happy for Jonas and wish him the best for his successful academic career in Douraods. We will miss you, Jonas. Congratulations!
  • (August, 2022) Jinchen Zhao’s second paper titled “Anomalous multicritical phenomena and frustration induced by synthetic magnetic fields” is uploaded to arXiv. Congratulations!
  • (Apr, 2022) Our research on “Frustrated Superradiant Phase Transition” is published in Physical Review Letters! This work identifies a novel type of phase transition called “frustrated superradiant phase transition” for the first time that occurs when the ground-state superradiance of cavity fields cannot simultaneously minimize the positive photon hopping interactions.  Journal Ref: Jinchen Zhao and Myung-Joong Hwang, Physical Review Letters 128, 163601 (2022)

  • (Dec, 2021) Jinchen Zhao’s first paper titled “Frustrated Superradiant Phase Transition” is uploaded to arXiv. Congratulations!
  • (Sep, 2021) Dr. Jonas F. G. Santos joins the quantum science group. Welcome Jonas!
  • (May, 2021) Four summer research scholars (Ho-Yun, Jinchen, Yue, Yuhang) join our group for intensive research over the summer.  Welcome!
  • (Nov, 2020) Our group receives a research grant from National Science Foundation of China (NSFC) for the investigation of critical phenomena in controlled quantum systems.
  • (June, 2020) Our research on quantum statistical enhancement of a quantum machine is published in Physical Review Letters! This work shows that quantum indistinguishability can be harnessed to enhance the performance of quantum engines. This paper is a result of an international collaboration with Prof. Gentaro Watanabe (Zhejiang), Prof. Prassana Venkatesh (IIT Gandhinagar), Prof. Peter Talkner (Augsburg), and Prof. Adolfo del Campo (Bilbao).  Journal Ref : Physical Review Letters 124, 210603 (2020)

 

  • (November, 2019)  Our research on dynamical scaling laws of Out-of-Time-Ordered Correlators (OTOC) is published in Physical Review B. The OTOC has recently been recognized as an important object to characterize dynamics of non-integrable many-body system. In this work, we establish a dynamical scaling law for the OTOC in the vicinity of quantum critical point and show the universality of butterfly velocity in a chaotic model such as a transverse axial nearest-neighborhood Ising model. This work has been done with a collaboration with Prof. Bo-Bo Wei (Shenzhen) and Prof. Gaoyong Sun (Nanjing). Journal Ref : Physical Review B 100, 195107 (2020)

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