Research

My research lies at the intersection of number theory, spectral theory, dynamics, and mathematical physics. I am particularly interested in the relationship between deterministic structure and statistical behavior: when do systems governed by precise rules exhibit patterns associated with randomness, and when do geometry or arithmetic prevent this?

Spectral theory and geometry

The spectrum of a differential operator connects analysis with the geometry of the underlying space. I am especially interested in the Laplacian on hyperbolic and locally symmetric spaces, where geometric and arithmetic structures interact.

How does geometry constrain the spectrum? How many exceptional eigenvalues can a space have, and how do these vary in families? How strongly can eigenfunctions concentrate? I am interested in these questions both for individual spaces and for families in which the geometry becomes increasingly complicated.

Three Laplacian eigenfunctions on a square, with alternating blue and ochre nodal regions.
Laplacian eigenfunctions on a square: a simple illustration of geometry shaping oscillation.

Quantum chaos

Quantum chaos concerns the relationship between classical motion and the behavior of quantum states and energy levels. A central theme of my research is how the distinction between integrable and chaotic classical dynamics is reflected in spectral statistics.

When should neighboring energy levels behave like independent random points, and when should they exhibit the correlations of random matrix theory? How uniformly do high-energy eigenfunctions spread through a space? What role do symmetries, and especially arithmetic symmetries, play in these questions? I am interested in understanding both the statistical predictions and the mechanisms behind them.

Number theory and dynamics

Simple arithmetic rules can generate sequences with remarkably intricate distributions. I study questions about equidistribution, the spacing of points, and correlations between them, particularly for sequences considered modulo one and for orbits of group actions.

When does a deterministic sequence resemble a random one at small scales? What distinguishes uniform distribution from genuinely Poissonian local statistics? How do Diophantine properties influence these patterns? A related interest is counting: how accurately can we count points in an orbit or a geometric region, and what can spectral information tell us about the error?

Fifty points on the unit interval in each of three examples: equally spaced points, fractional parts of square root of two times n squared, and independent uniform random points.
Fifty points in each example: equal spacing, an arithmetic sequence modulo one, and independent random sampling.

Statistical mechanics and transport

I am interested in how macroscopic laws emerge from microscopic motion, especially in models of particles moving among scatterers. These systems provide a setting in which deterministic dynamics, geometric constraints, and randomness meet.

When does a particle’s motion become diffusive? On what time scales does it lose memory of its past? How do repeated encounters, long-range correlations, and the arrangement of scatterers affect transport? More broadly, I would like to understand when a complicated microscopic evolution can be described by a simpler stochastic process or a macroscopic differential equation.

Three illustrative trajectories in random scatterer configurations: straight flights among disks in the random Lorentz gas, reflections among aligned squares in the random wind-tree model, and curved flights among disks in the magnetic random Lorentz gas.
The random Lorentz gas, the random wind-tree model, and the magnetic random Lorentz gas. Randomly placed scatterers interrupt straight flights; a magnetic field bends the flights into circular arcs.