Rice University Applied Physics Program

Masters Thesis Defense: Wanbing Zhao
Date & Time: August 6, 2026, 2:00 to 3:00 PM
Location: SST 301A (+Zoom)

Host Department: Physics & Astronomy
Advisor: Vir B Bulchandani
Committee: Kaden Hazzard, Guido Pagano

Title: Quantifying Many-Body Contextuality with Multiplayer Nonlocal Games from Stabilizer Codes

Abstract:
Quantum contextuality is a fundamental property of quantum mechanics that captures the impossibility of reproducing quantum measurement outcomes from pre-existing classical values. Contextuality in few-particle quantum systems is commonly studied using Bell inequalities, but its emergence in large-scale, many-particle quantum systems remains poorly understood. Such many-body contextuality has attracted renewed attention in quantum information science through its formulation in terms of ``nonlocal games'' played with stabilizer codes, which are mathematically equivalent to Bell inequalities. However, work in this field has largely focused on determining whether such nonlocal games exhibit quantum advantage. To quantify many-body contextuality, we develop a systematic theory of nonlocal games defined on n-qubit stabilizer codes via nonlinear Boolean functions. The theory yields a universal upper bound of 7/8 on the classical value of such games that admit quantum advantage. For cyclic cluster states and toric codes, we prove that the classical values of the associated games approach 1/2 exponentially fast in n, resulting in exponentially large Bell-inequality violations. Going beyond these lattice examples, we show that exponential Bell-inequality violations are generic among random graph states, occurring with high probability over Erdős–Rényi ensembles with fixed edge probability p \in (0,1). These results provide a scalable path toward testing quantum contextuality on current and future quantum devices.

Applied Physics Graduate Student Kiran Kulkarni recently visited Prof. Anoop Thomas and the Chemical Sciences team at the Indian Institute of Science in Bengaluru, India, to learn the experimental techniques behind their discovery of enhanced conductivity in cavity-coupled polystyrene.

Rising 4th year APP student Wanbing Zhao of the Bulchandani Lab had the opportunity to practice her thesis presentation before her Master's Defense to be held Thursday, August 6th.

Masters Thesis Defense: T. A. M. Ragib Shahriar
Date: Thursday, July 30 at 3:00 pm
Location: Ralph O'Connor Building (OES) 131

Host Department: MSNE
Advisor: Hanyu Zhu
Committee: Yonglong Xie, Harris Pirie

Title: Symmetry-Resolved Nonlinear Optical Spectroscopy of Twisted Interfaces

Abstract: Stacking two crystals with a relative twist creates a moir´e superlattice whose symmetry belongs to neither constituent. In complex oxides this degree of freedom remains largely unexplored and should differ qualitatively from the van der Waals case, since the layers meet through ionic–covalent bonds and can rebond and reconstruct at the junction. The difficulty is that the reconstructed region is a few unit cells thick and buried between two far thicker crystals.

Optical second harmonic generation (SHG) is forbidden in a centrosymmetric bulk within the electric-dipole approximation, so in SrTiO3 (STO) it reports only from surfaces and buried interfaces. Using polarization- and rotation-resolved broadband SHG with nonlinear susceptibility tensor analysis, I first show that the four-fold anisotropy of bare (001) STO arises from the anisotropic bulk electric-quadrupole term rather than the azimuthally isotropic 4mm surface dipole. Modeling a 36◦-twisted STO membrane bilayer as a coherent superposition of surface, bulk-quadrupole, and interfacial sources then yields an interfacial nonlinearity ≈ 0.68 times the STO surface dipole, with a finite imaginary part indicating a near-resonant interfacial electronic structure; first-principles, Raman, and electron microscopy results from collaborators attribute it to an asymmetric SrO–TiO2 interface formed on annealing.

Because inversion breaking is a weaker condition than chirality, I further developed circular-dichroism SHG and artifact-corrected solid-state circular dichroism, establishing the instrumental floor that any claim of handedness must clear; applied to a twisted STO bicrystal, both are reported as quantitative bounds. I also contributed SHG characterization to studies of fluorinated cubic boron nitride, MoS2 nanoribbon moir´e quantum dots, ferroelectric thin film, and several intermetallic systems. Finally, I propose extending this toolkit from second-harmonic to sum-frequency generation in order to measure the vibrational spectrum of a Wigner crystal—the electron lattice formed when Coulomb repulsion dominates kinetic energy—in transition-metal-dichalcogenide moir´e heterostructures, whose phonons no existing probe resolves directly. This is the subject of my future research, and the apparatus for it has been rebuilt in preparation.

APP faculty & students are invited to attend a poster session featuring SCI summer exchange students from Nanyang Technological University. Please see email to RSVP.

The NTU summer exchange program is a 2-month undergraduate research program that is designed to immerse the students in a dynamic learning environment across multiple engineering disciplines. In addition to the six students who came to Rice from Singapore, six Rice students have travelled to Singapore for similar research experiences. This is the second year that Rice and NTU have collaborated on this program.

APP students are invited to register for upcoming CAPC workshops next week! Please see the email link to register for one or both workshops by Friday, July 24th.

Applications for 2026 GCURS are now open!

APP students and visiting undergraduate students from Nanyang Technological University in Singapore toured NASA and Johnson Space Center last weekend!