Leo Radzihovsky

Leo Radzihovsky is a Russian American condensed matter physicist and academic, who currently serves as a professor of distinction in Physics at the University of Colorado Boulder. Radzihovsky's theoretical research integrates classical and quantum aspects of condensed matter, revealing novel states of matter and phase transitions between them, driven by strong fluctuations and/or spatial heterogeneity.^[1]

He is the recipient of the LeRoy Apker Award,^[2] Jonsson Valedictorian Prize, and the NSF CAREER Award.^[3] Radzihovsky is a Simons Foundation Investigator,^[4] a Fellow of the David and Lucile Packard Foundation,^[5] a Fellow of the American Physical Society,^[6] and an Alfred P. Sloan Research Fellow.^[3]

Born in Saint Petersburg, Russia, Radzihovsky immigrated to the US in 1980. In 1988, he earned his B.S. and M.S. in physics with a minor in Electrical Engineering from Rensselaer Polytechnic Institute (RPI).^[7] After graduating from RPI, he received the 1989 LeRoy Apker National Award for best undergraduate physics research on electron transport in nondegenerate semiconductors.^[8] He completed his Ph.D. at Harvard in 1993, supported by the Hertz Graduate Fellowship,^[9] and pursued a Postdoctoral Fellowship at the James Franck Institute at the University of Chicago.^[10]

Radzihovsky started his academic career as an assistant professor of physics at CU Boulder in 1995,^[11] was promoted to associate professor in 2001 and then to Professor in 2003,^[11] and was named a Professor of Distinction in 2023.

At KITP he served as a member of the advisory board during 2013–2017, and its chair in 2015–2016.^[12] He has served as a Member at Large of the Executive Committee at APS from 2019 to 2022,^[13] and a member of the Oliver Buckley, Lars Onsager Prize (chair in 2009) and APS Fellow Committees. He has served as a member of the editorial board for the Annals of Physics (2001–2012) and on the board for the Annual Review of Condensed Matter Physics since 2015.^[14] As of 2025 he is the editor of the Annual Review of Condensed Matter Physics.^[15]

Radzihovsky's theoretical research is focused on the interplay and synergy between classical "soft" and quantum "hard" condensed matter and macroscopic systems that consist of fluids and solids of strongly interacting constituents, be they electrons, atoms, molecules, or bacteria. He uses methods of many-body field theory and renormalization group to treat strong non-perturbative effects of fluctuations and nonlinearities that are at play in condensed matter systems. Many of such strongly fluctuating condensed matter systems form universal states that he dubbed critical matter.^[16]

In classic soft matter, Radzihovsky has studied fluctuations, anisotropy, topological defects, and quenched disorder-driven phenomena in tensionless elastic membranes (realized by biological lipid bilayers, cytoskeletal networks, and single-atom thin graphene sheets).^[17] These include anomalous elasticity with universal negative Poisson ratio and length-scale dependent elastic moduli, wrinkling, buckling, glassiness, tubule ordering, and associated entropically driven phase transitions.^[18]

Radzihovsky explored vortex glassy matter of type-II superconductors in magnetic field, charge density waves (CDW), Wigner and colloidal crystals pinned by a substrate and/or an ever-present random quenched disorder, and broadly researched non-equilibrium dynamics and phase transitions of such driven elastic media.^[19]

Radzihovsky contributed to liquid crystal phases and their phase transitions. These include novel banana bent-core shaped mesogens, anti- and ferroelectric nematic and smectic phases, and spontaneously chiral and cholesteric liquid crystals.^[20] He also led studies of nematic and smectic liquid crystals confined inside random porous matrix of aerogel^[21] and, with his students, subjected to surface pinning by a heterogenous substrate (as in a laptop or iPhone display),^[22] and liquid crystalline elastomers and rubber.^[23]

In quantum hard matter, Radzihovsky's contributions include predictions regarding degenerate atomic gases (AMO systems) controlled by narrow Feshbach resonances, which he used to study BCS-BEC crossover in paired balanced^[24] fermionic superfluids. He showed the latter to be a route to the Fulde-Ferrel-Larkin-Ovchinikov (FFLO) "pair-density wave" state,^[25] at nonzero temperature predicted to be a charge-4e superconductor,^[26] its exotic descendant states, and their quenched non-equilibrium dynamics and phase transitions.^[27] He further demonstrated finite-angular momentum Feshbach resonances as a mechanism toward a realization of topological paired superfluidity and concomitant Majorana vortex modes, of interest for topological quantum computing.^[28] Applying these Feshbach resonances to degenerate bosonic atom counterparts, he with his Ph.D. students predicted novel molecular and finite-momentum superfluid phases,^[29] with the former recently observed experimentally.^[30]

Radzihovsky investigated transport and tunneling through quantum Hall (QH) bilayers,^[31] and studied quantum "flocking" and non-equilibrium hydrodynamics in microwave-irradiated QH systems,^[32] (with Alan Dorsey) QH nematic in partially filled high Landau levels, and associated quantum phase transitions.^[33] He studied disorder-driven quantum phase transitions in Dirac and Weyl semimetals.^[34]

Radzihovsky has also worked on the relation of gapless "fracton" states of matter as tensor-gauge theory duals of topological defects in quantum crystals, and their Higgs transitions as quantum melting into supersolid, smectic, and nematic states of matter.^[35]

• 1998 – Fellow, David and Lucile Packard Foundation^[5]
• 2003 – Fellow, American Physical Society^[6]
• 2014 – Simons Investigator in Physics, Simons Foundation^[4]
• 2023 – Professor of Distinction, University of Colorado

• Le Doussal, P., & Radzihovsky, L. (1992). Self-consistent theory of polymerized membranes. Physical review letters, 69(8), 1209.
• Radzihovsky, L., & Toner, J. (1997). Nematic–to–Smectic-A Transition in Aerogel. Physical review letters, 79(21), 4214.
• Bellini, T., Radzihovsky, L., Toner, J., & Clark, N. A. (2001). Universality and scaling in the disordering of a smectic liquid crystal. Science, 294(5544), 1074-1079.
• Gurarie, V., Radzihovsky, L., & Andreev, A. V. (2005). Quantum phase transitions across a p-wave Feshbach resonance. Physical review letters, 94(23), 230403.
• Sheehy, D. E., & Radzihovsky, L. (2006). BEC-BCS crossover in “magnetized” Feshbach-resonantly paired superfluids. Physical review letters, 96(6), 060401.
• Gurarie, V., & Radzihovsky, L. (2007). Resonantly paired fermionic superfluids. Annals of Physics, 322(1), 2-119.
• Pretko, M., & Radzihovsky, L. (2018). Fracton-Elasticity Duality. Physical Review Letters. 120 (19): 195301.
• Agterberg, D. F., Davis, J. S., Edkins, S. D., Fradkin, E., Van Harlingen, D. J., Kivelson, S. A.,... Radzihovsky, L. & Wang, Y. (2020). The physics of pair-density waves: Cuprate superconductors and beyond. Annual Review of Condensed Matter Physics, 11, 231-270.