Terahertz chiral photonic-crystal cavities for Dirac gap engineering in graphene

Fuyang Tay; Stephen Sanders; Andrey Baydin; Zhigang Song; Davis M Welakuh; Alessandro Alabastri; Vasil Rokaj; Ceren B Dag; Junichiro Kono

doi:10.1038/s41467-025-60335-x

Terahertz chiral photonic-crystal cavities for Dirac gap engineering in graphene

Nat Commun. 2025 Jun 6;16(1):5270. doi: 10.1038/s41467-025-60335-x.

Authors

Fuyang Tay^{1

2}, Stephen Sanders³, Andrey Baydin^{3

4

5}, Zhigang Song⁶, Davis M Welakuh⁷, Alessandro Alabastri^{3

4

5}, Vasil Rokaj^{8

9

10}, Ceren B Dag^{8

9

11}, Junichiro Kono^{12

13

14

15

16}

Affiliations

¹ Department of Electrical and Computer Engineering, Rice University, Houston, TX, USA. fuyang.tay@columbia.edu.
² Applied Physics Graduate Program, Smalley-Curl Institute, Rice University, Houston, TX, USA. fuyang.tay@columbia.edu.
³ Department of Electrical and Computer Engineering, Rice University, Houston, TX, USA.
⁴ Smalley-Curl Institute, Rice University, Houston, TX, USA.
⁵ Rice Advanced Materials Institute, Rice University, Houston, TX, USA.
⁶ John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.
⁷ Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany.
⁸ Department of Physics, Harvard University, Cambridge, MA, USA.
⁹ ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA.
¹⁰ Department of Physics, Villanova University, Villanova, PA, USA.
¹¹ Department of Physics, Indiana University, Bloomington, IN, USA.
¹² Department of Electrical and Computer Engineering, Rice University, Houston, TX, USA. kono@rice.edu.
¹³ Smalley-Curl Institute, Rice University, Houston, TX, USA. kono@rice.edu.
¹⁴ Rice Advanced Materials Institute, Rice University, Houston, TX, USA. kono@rice.edu.
¹⁵ Department of Physics and Astronomy, Rice University, Houston, TX, USA. kono@rice.edu.
¹⁶ Department of Materials Science and NanoEngineering, Rice University, Houston, TX, USA. kono@rice.edu.

Abstract

Strong coupling between matter and vacuum electromagnetic fields in a cavity can induce novel quantum phases in thermal equilibrium via symmetry breaking. Particularly intriguing is the coupling with circularly polarized cavity fields, which can break time-reversal symmetry (TRS) and lead to topological bands. This has spurred significant interest in developing chiral cavities that feature broken TRS, especially in the terahertz (THz) frequency range, where various large-oscillator-strength resonances exist. Here, we present a design for high-quality-factor THz chiral photonic-crystal cavities (PCCs) that achieve broken TRS using a magnetoplasma in a lightly doped semiconductor. We incorporate ab initio density functional theory calculations into the derived microscopic model, allowing a realistic estimate of the vacuum-induced gap in graphene when coupled to our chiral cavity. Our calculations show an enhancement in the light-matter interaction due to Dirac nodes and predict an energy gap on the order of 1 meV. The THz chiral PCCs offer a promising platform for exploring cavity-dressed condensed matter with broken TRS.

Abstract

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