Bio


Rubaiat received his undergraduate degree in Applied Physics from the University of Tokyo in 2017. He then moved to the University of California San Diego where he finished his PhD in Physics under Professor Richard Averitt in 2023. During his PhD, he performed time-resolved broadband terahertz spectroscopy on excitonic insulator candidate Ta2NiSe5 where he demonstrated light-induced terahertz parametric amplification mediated by phonon squeezing. He has also worked on the optical control of plasmonic modes in semiconducting metamaterials. Currently, Rubaiat is a postdoctoral scholar at Stanford University working with Professors Tony Heinz and Aaron Lindenberg on the strong light-field dynamics of low-dimensional materials. His research interests also include cavity QED and Floquet engineering of quantum materials.

Boards, Advisory Committees, Professional Organizations


  • Member, American Physical Society (2017 - Present)
  • Member, Optica (2020 - Present)

Professional Education


  • PhD, University of California San Diego, Physics (2023)
  • B.S., The University of Tokyo, Applied Physics (2017)

Stanford Advisors


All Publications


  • Terahertz parametric amplification as a reporter of exciton condensate dynamics. Nature materials Haque, S. R., Michael, M. H., Zhu, J., Zhang, Y., Windgätter, L., Latini, S., Wakefield, J. P., Zhang, G. F., Zhang, J., Rubio, A., Checkelsky, J. G., Demler, E., Averitt, R. D. 2024

    Abstract

    Condensates are a hallmark of emergence in quantum materials such as superconductors and charge density waves. Excitonic insulators are an intriguing addition to this library, exhibiting spontaneous condensation of electron-hole pairs. However, condensate observables can be obscured through parasitic coupling to the lattice. Here we employ nonlinear terahertz spectroscopy to disentangle such obscurants through measurement of the quantum dynamics. We target Ta2NiSe5, a putative room-temperature excitonic insulator in which electron-lattice coupling dominates the structural transition (Tc = 326 K), hindering identification of excitonic correlations. A pronounced increase in the terahertz reflectivity manifests following photoexcitation and exhibits a Bose-Einstein condensation-like temperature dependence well below the Tc, suggesting an approach to monitor the exciton condensate dynamics. Nonetheless, dynamic condensate-phonon coupling remains as evidenced by peaks in the enhanced reflectivity spectrum at select infrared-active phonon frequencies, indicating that parametric reflectivity enhancement arises from phonon squeezing. Our results highlight that coherent dynamics can drive parametric stimulated emission.

    View details for DOI 10.1038/s41563-023-01755-2

    View details for PubMedID 38172546

  • Generalized Fresnel-Floquet equations for driven quantum materials PHYSICAL REVIEW B Michael, M. H., Foerst, M., Nicoletti, D., Ul Haque, S., Zhang, Y., Cavalleri, A., Averitt, R. D., Podolsky, D., Demler, E. 2022; 105 (17)
  • Broadband Terahertz Silicon Membrane Metasurface Absorber ACS PHOTONICS Huang, Y., Kaj, K., Chen, C., Yang, Z., Ul Haque, S., Zhang, Y., Zhao, X., Averitt, R. D., Zhang, X. 2022; 9 (4): 1150-1156
  • Structural tuning of nonlinear terahertz metamaterials using broadside coupled split ring resonators AIP ADVANCES Keiser, G. R., Karl, N., Ul Haque, S., Brener, I., Mittleman, D. M., Averitt, R. D. 2021; 11 (9)

    View details for DOI 10.1063/5.0053876

    View details for Web of Science ID 000724151000010

  • On-chip terahertz modulation and emission with integrated graphene junctions APPLIED PHYSICS LETTERS Island, J. O., Kissin, P., Schalch, J., Cui, X., Ul Haque, S., Potts, A., Taniguchi, T., Watanabe, K., Averitt, R. D., Young, A. F. 2020; 116 (16)

    View details for DOI 10.1063/5.0005870

    View details for Web of Science ID 000529494000001