Smalley-Curl Institute

Masters Thesis Defense: Wen-Hua Wu
Date & Time: Friday, June 12th | 9:00 - 11:00 AM
Location: SST 301A

Host Department: ECE
Advisor: Junichiro Kono
Committee: Junichiro Kono, Songtao Chen, Kaden Hazzard

Title: Floquet-Driven Superradiant Phase Transition in Ultrastrongly Coupled Landau Polaritons

Abstract
This thesis investigates light–matter interactions in condensed matter through Floquet engineering and terahertz spectroscopy. On the theoretical side, we propose a framework for a Floquet-driven superradiant phase transition (SRPT) in Landau polaritons. By temporally modulating the magnetic field, we circumvent the Thomas–Reiche–Kuhn sum rule no-go theorem, enabling a second-order phase transition and photon condensation. We evaluate the experimental implementation of Floquet-driven SRPTs, highlighting the role of thermal effects and the necessity of metasurfaces for efficient field modulation. These results advance the fields of cavity quantum electrodynamics and many-body Floquet dynamics. Additionally, we utilized terahertz time-domain spectroscopy to study the quantum spin liquid candidate α-RuCl3. High-field measurements in the Voigt geometry reveal broadening of the absorption line, offering key evidence for the quantum spin liquid phase. We also explored ultrafast carrier dynamics in a PbTe thin film and identified nonlinearities in GaAs-based Landau polaritons, where spatial inhomogeneities and nonparabolicity invalidate the standard linear bosonic model.

Zoom link
https://zoom.us/j/95270116497?pwd=aBNECf0z1CZj5HPpC9vM0GblGixPFW.1

Congratulations to DOCTOR Shengjie Yu on a successful defense!

Doctoral Thesis Defense: Shengjie Yu
Date & Time: June 9, 2026, 1:00 PM
Location: Brockman Hall for Physics BRK 200

Host Department: ECE
Advisor: Prof. Junichiro Kono
Committee: Prof. Geoff Wehmeyer, Prof. Douglas Natelson, Prof. Matteo Pasquali

Title: Electronic Transport in Aligned Carbon Nanotube Assemblies

Abstract:
Carbon nanotubes (C**s) are widely used to study quantum transport in low-dimensional systems because of their one-dimensional electronic structure and long phase-coherence lengths. In practical materials, however, C**s assemble into bundles, fibers, and aligned films, where intertube coupling, disorder, anisotropy, and current-path distribution reshape transport signatures. This dissertation examines how phase-coherent transport appears across this hierarchy in macroscopic CNT fibers, exfoliated CNT bundles, and aligned CNT films, using temperature-dependent transport, magnetotransport, nonlocal measurements, and angular-dependent magnetotransport.

In highly aligned CNT fibers, the direct observations are metallic high-temperature transport and a pronounced positive low-temperature magnetoconductance with field dependence characteristic of weak localization (WL). These measurements show that phase-coherent corrections remain observable in a macroscopic CNT conductor. Fits to the magnetoconductance also show that single-dimensional WL models are insufficient. An effective mixed-dimensional interpretation, combining bundle-scale quasi-one-dimensional coherence with a more extended diffusive contribution, provides a constrained phenomenological description of the fiber response.

Individual CNT bundles exfoliated from the fibers reveal WL-like low-field magnetoconductance, reproducible universal conductance fluctuations (UCF), and nonlocal field-dependent signals over micron-scale separations. Comparing these probes gives the central conceptual result: the WL field scale, UCF amplitude, and nonlocal response define different operational coherence scales. The corresponding interpretation is trajectory dependent, with short, flux-sensitive diffusive loops coexisting with a subset of pathways that remain correlated over longer portions of the bundle.

Aligned CNT films show how current direction, channel length, and field orientation control transport in a planar anisotropic network. Perpendicular transport is hopping-dominated and exhibits a low-temperature dimensional crossover, whereas parallel transport is more conductive and shows low-field magnetotransport compatible with a phenomenological WL-like description. Long-channel devices average over network anisotropy more strongly, while shorter channels make directional magnetotransport more visible; angular-dependent magnetotransport further distinguishes angularly averaged response from anisotropic flux sensitivity.

Overall, the thesis shows that phase-coherent signatures remain experimentally observable in aligned CNT assemblies, but their interpretation depends on the observable and measurement geometry.

Zoom link:
https://riceuniversity.zoom.us/j/92604535244?pwd=vwzT4vkEbkPaMpYsQ6LrBcbXmBawOU.1

Meeting ID: 926 0453 5244
Passcode: 466907

APP students, faculty, and alumni are invited to join SCI members as we welcome visiting summer exchange students from NTU Singapore. There will be pizza and an open tab at Valhalla! Please see email to RSVP.

Save the date! The 40th annual SCI Summer Research Colloquium will be Friday, August 7th. Registration details coming soon.

We are pleased to announce the recipients of the APP travel awards for Summer 2026! We had many excellent applications this year for these competitive awards. Students will receive funding to cover a portion of expenses incurred for travel to and/or participation in a conference or scientific meeting related to their research this term. Thank you to all nominating faculty and congratulations to the recipients!

Masters Thesis Defense: George Tomaras
Date & Time: Friday, May 8 at 9:00 am
Location: Brockman Hall for Physics, BRK200 (+Zoom)

Host Department: Physics and Astronomy
Advisor: Guido Pagano
Committee: Thomas C. Killian, Songtao Chen

Title: Individual Addressing of Trapped Ions for Quantum Simulation of Coherent and Dissipative Dynamics

Abstract:
Trapped ions interacting with electromagnetic radiation have been a successful platform for the simulation of quantum systems. This thesis details the design and characterization of an optical system that enables individual addressing of trapped ions for quantum simulation of coherent and dissipative dynamics via stimulated Raman transitions. The shared harmonic motion of the ions is utilized for selective entanglement and sympathetic cooling. To realize this architecture, active stabilization of the power, repetition rate, and pointing were implemented for a 355-nm pulsed laser. Optical manipulation delivers an array of 1 × 11 beams with horizontal waists of ∼ 1.2 µm, spacing of ∼ 4.4 µm, and optical crosstalk of ∼ 10−12. This versatile apparatus will enable the simulation of complex phenomena, including exciton transfer in biological systems, three-body couplings in lattice field theories, and digital-analog hybrids with the aid of a spatial light modulator.

Zoom link
https://riceuniversity.zoom.us/j/94535512945?pwd=5V4fMeqQ6EbqJ6sCld8d230EmOvXeE.1

3rd year APP student George Tomaras in the Pagano Lab, presented at last week's RQI Quantum Group meeting.

Masters Thesis Defense: Luke Kay
Date & Time: Thursday, April 30, 2026 10:00 am
Location: BRK 300 (+Zoom)

Host Department: ECE
Advisor: Naomi Halas
Committee: Peter Nordlander, Alessandro Alabastri

Title: Engineering Tunable Plasmonic Materials for Near- and Mid-Infrared Nanophotonics

Abstract
Mid- and near-infrared spectral regions are critical for emerging applications in photodetection, chemical sensing, and photocatalysis, where plasmonics enables strong electromagnetic field enhancement and confinement. However, the development of plasmonic materials in these regimes remains limited by incomplete understanding of their optical permittivities and morphological variability, leaving some spectral regions largely unexplored. In this thesis, tunable plasmonic platforms are developed for the design of next-generation nanophotonic devices and metasurfaces. Titanium oxynitride (TiOxNy) is investigated as a near-infrared material, with its plasmonic behavior tailored through controlled synthesis pathways. Gallium-doped zinc oxide (GZO) is explored as a mid-infrared plasmonic material, where its optical response is tuned via gallium doping concentration. Spectroscopic ellipsometry is employed to extract the complex permittivity of these materials, providing detailed insight into their optical behavior across a broad spectral range. These results enable accurate modeling and optimization of plasmonic structures, establishing a pathway toward scalable, tunable platforms for infrared nanophotonics.

Zoom link:
https://riceuniversity.zoom.us/j/96778429842?pwd=wbtEcHwjnxSRw6uwnnhKIocWhoFepF.1

Meeting ID: 967 7842 9842
Passcode: 092888

The next RQI meeting will be this Friday, April 24th, at noon, in SST 300. This meeting's presentation is "Individual Addressing of Trapped Ions for Simulation of Coherent and Dissipative Dynamics" by APP student George Tomaras in the group of Prof. Guido Pagano.

For more details on this and other RQI seminars, please visit the RQI website: https://quantum.rice.edu/seminars.