PhD and Post Doc Quantum Seminar Series: Mathieu Ouellet

The QUIEST Center is thrilled to be kicking off a new seminar series this semester geared towards PhD and Post Doc students across SEAS and SAS to present on quantum-related topics of their choosing. Read on for more information on this week’s seminar presentation:

Presentation by:

Mathieu Ouellet, PhD student in Quantum Engineering Lab

Talk Title:

“A graph-based representation of quantum dynamics and control”

Abstract:

We present a method for representing quantum-mechanical dynamics associated with time-dependent Hamiltonians through a graph-based approach, enabling efficient computation of the evolution operator and its gradients through physically motivated approximations.

This methodology transforms the Hamiltonian into a graph, where vertices represent basis states and edges denote non-zero Hamiltonian matrix elements, thus representing time evolution as paths on the network. By employing the Volterra composition and enumerating the graph’s cycles and paths, we efficiently compute the time-ordered exponential operator, enabling both the exploration of Hamiltonian dynamics and the optimization of quantum control protocols. We demonstrate the utility of this representation through several application examples, ranging from optimizing quantum control sequences for quantum gates to devising efficient quantum measurement strategies.