I study topological phases of matter. My research includes the discovery of Quantized Multipole Insulators (Science, 2017) and topological insulators derived from them, now known as Higher-order Topological Insulators (PRB, 2017) and Superconductors (PRB,2014). I have also contributed to the implementation of analogs of these phases in photonic (Nature Photonics, 2018), microwave resonator (Nature, 2018), and electronic (Nature Materials, 2019) platforms. My most recent work is on the bulk-boundary correspondence of these phases (PRB, 2019, Science, 2020), on the existence of boundary-obstructed topological phases (PRX, 2020, PRR,2021), and on predicting and finding symmetry-protected topological ‘bound states in the continuum’ (PRB, 2019, PRL,2020).
Press
At the core of our understanding and classification of topological phases is the concept of dipole moment in crystalline insulators. During my time at the University of Illinois at Urbana-Champaign, my collaborators and I expanded this notion by discovering that crystalline insulators can additionally host quadrupole and octupole moments (see a summary in EurekAlert!). As an extension, a new family of topological phases has emerged in the past years, which go by the name of ‘higher-order topological insulators’ (see Topological Insulators Turn a Corner).
The discovery of these phases coincided with an increasing ability to generate analogs of topological phases in synthetic materials. We developed the first higher-order topological phase in a photonic system (see a short summary here). Several realizations followed in photonic, mechanical, and electrical lattices (see Waves Cornered, Topology reaches higher spheres, and Topological lattices lit at the corners), as well as in 2D atomic lattices engineered by STM manipulation (see Protected corners).
Selected Publications
(Links to my complete list of publications in Google Scholar and the arXiv).
14. Point-Defect-Localized Bound States in the Continuum in Photonic Crystals and Structured Fibers
Vaidya S., Benalcazar W. A., Cerjan A., Rechtsman M.
Phys. Rev. Lett. 127 (2), 023605, 2021
13. Boundary-obstructed topological phases
Khalaf E., Benalcazar W. A., Hughes, T. L., Queiroz R.
Phys. Rev. Research, 3, 013239, 2021
12. Observation of a higher-order topological bound state in the continuum
Cerjan A., Jurgensen M., Benalcazar W. A., Mukherjee S., Rechtsman M.
Phys. Rev. Lett. 125, 213901, 2020
Selected as Editors’ suggestion
11. Boundary-obstructed topological high-Tc superconductivity in iron pnictides
Wu X., Benalcazar W. A., Li Y., Thomale R., Liu C. X., Hu J.
Phys. Rev. X, 10, 041014, 2020
10. A fractional corner anomaly reveals higher-order topology
Peterson C. W., Li T., Benalcazar W. A., Hughes T. L., Bahl G.
Science 368 (6495), 1114-1118, 2020
9. Bound states in the continuum of higher-order topological insulators
Benalcazar W. A., Cerjan A.
Phys. Rev. B 101, 161116, 2020
8. Fractional corner charges in spin-orbit coupled crystals
Schindler F., Brzezinska M., Benalcazar W. A., Iraola M., Bouhon A., Tsirkin S. S., Vergniory M. G., Neupert T.
Phys. Rev. Research 1 (3), 033074, 2019
7. Strong nonreciprocity in modulated resonator chains through synthetic electric and magnetic fields
Peterson C. W., Benalcazar W. A., Lin M., Hughes T. L., Bahl G.
Phys. Rev. Lett. 123, 063901, 2019
6. Quantization of fractional corner charge in Cn-symmetric topological crystalline insulators
Benalcazar W. A., Li T., Hughes T. L.
Phys. Rev. B 99 (24), 245151, 2019
Selected as Editors’ suggestion
5. Topological protection of photonic mid-gap cavity modes
Jiho N., Benalcazar W. A., Sheng H., Collins M. J., Chen K., Hughes T. L., and Rechtsman M. C.
Nature Photonics 12, 408-415, 2018
4. A quantized microwave quadrupole insulator with topologically protected corner states
Peterson C. W., Benalcazar W. A., Hughes T. L., and Bahl G.
Nature 555, 346-350, 2018
3. Electric multipole moments, topological multipole moment pumping, and chiral hinge states in crystalline insulators
Benalcazar W. A., Bernevig B. A., and Hughes T. L.
Phys. Rev. B 96, 245115, 2017
Selected as Editors’ suggestion and featured in a Viewpoint
Also, selected as a 50th Anniversary Milestone Paper by Phys. Rev. B.
2. Quantized electric multipole insulators
Benalcazar W. A., Bernevig B. A., and Hughes T. L.
Science 357 (6346), 61-66, 2017
1. Classification of two-dimensional topological crystalline superconductors and Majorana bound states at disclinations
Benalcazar W. A., Teo J. Y., and Hughes T. L.
Phys. Rev. B 89 (22), 224503, 2014