Washington Quantum Computing Meetup

Summary: We present a measurement-driven quantum framework for evaluating overlap and Hamiltonian matrix elements in spin-coupled generalized valence bond (SCGVB) wavefunctions. The approach targets a central difficulty of nonorthogonal valence-bond methods: estimating matrix elements between distinct, generally nonorthogonal configuration state functions. Rather than preparing the full wavefunction on quantum hardware, we reformulate the required quantities as vacuum expectation values of Pauli-string operators that can be accessed using shallow, ancilla-free circuits composed of local Clifford rotations and computational-basis measurements. In contrast to Hadamard-test-based matrix-element estimation, this construction avoids ancilla qubits and controlled operations by reducing the problem to local Pauli measurements. This separates the algebraic construction of the SCGVB problem from the measurement task executed on the quantum register and yields a low-depth strategy compatible with near-term architectures. We demonstrate the framework on square and rectangular H4 using quantum-circuit emulation, where the resulting overlap and Hamiltonian matrices reproduce classical Lowdin-based references with good accuracy across the geometries considered, and where derived Coulson-Chirgwin weights remain chemically consistent. These results support the feasibility of measurement-based quantum assistance for nonorthogonal SCGVB expansions and provide a practical route for incorporating quantum measurements into valence-bond electronic-structure workflows. Reference: https://arxiv.org/abs/2603.12045

Speaker: Dr. Bruna Gabrielly is a postdoctoral fellow at Purdue University. She completed a one-year postdoctoral appointment at the Center for Quantum Information and Control (CQuIC) at the University of New Mexico (UNM) in Prof. Akimasa Miyake's group. She earned her Ph.D. with Summa Cum Laude honors from The Autonomous University of Barcelona (UAB), where she conducted her research in two different institutes affiliated with the Barcelona Institute of Science and Technology (BIST). The rest part of her thesis focused on the exploration of entanglement in graphene-based materials under the supervision of Prof. Stephan Roche and Dr. Aron Cummings at ICN2. The second part delved into the study of many-body quantum states under the guidance of Prof. Antonio Acin at ICFO. Her thesis, titled 'Quantum Information in Lattices,' was funded by a Marie Sklodowska-Curie fellowship. During her Ph.D., she worked in part-time at IBM Quantum and was actively involved in the Qiskit Quantum Community, where she contributed to teaching, mentorship, community building, and cutting-edge research. Before commencing her Ph.D., she received training in the Conformal Bootstrap program. Bruna earned both a Bachelor's and a Master's degree in Theoretical Physics and Chemical Engineering in Recife, Brazil.

Title: A Theorist’s Quantum Simulations with Rydberg Atom Arrays
Date: August 15 2026 Noon - 14:00 EDT
Abstract:
Unprecedented control of light-atom interactions presents a unique opportunity to physicists to prepare fundamentally interesting and technologically useful quantum states of matter. I will highlight two recent quantum simulations that we performed on remotely accessible Rydberg atom array of QuEra Computing. In the first one [1], we experimentally investigate the far from equilibrium physics of transverse-field Ising model, a prototypical model in statistical mechanics, and uncover significant deviations from the theoretical predictions. We theoretically traced this discrepancy to atom motion which acts as an emergent disorder in Rydberg atom arrays and elucidated our observations with a minimal random spin model. In the second quantum simulation [2], we prepared a multi-partite entangled state known as W state in quantum information science by employing quantum many-body physics of topological ring frustration. To demonstrate quantum coherence and entanglement in the experimentally prepared state, we developed a Bayesian state tomography protocol and bounded the measured state fidelity. These works show that, as NISQ technologies advance, the gap between theory and experiment in quantum simulation is narrowing, ushering in an era where quantum simulation is becoming an essential tool in the theorist’s toolbox.
Reference:
[1] Phys. Rev. Lett. 135, 250403 (2025) https://journals.aps.org/prl/abstract/10.1103/jr7l-2cfb
[2] arXiv:2510.17974 https://arxiv.org/abs/2510.17974

Speaker: Dr. Ceren Dag is an assistant professor of the physics department in Indiana University, Bloomington.
She earned her Ph.D. in Physics from University of Michigan Ann Arbor in 2021. She was a ITAMP postdoctoral fellow at Harvard University. Her publications can be found at https://scholar.google.com/citations?user=gAKYr8sAAAAJ&hl=en

Title: Mesh-Free Numerical Method for Dirichlet Eigenpairs of the Laplacian with Potential
Date: September 7 2026 (Monday Holiday) 10:00 am - Noon EDT
Summary: This paper is concerned with the numerical approximation of the L^2 Dirichlet eigenpairs of the operator -delta + V on a simply connected C^2 bounded domain containing the origin, where is a radial potential. We propose a mesh-free method inspired by the Method of Particular Solutions for the Laplacian (i.e. ). Extending this approach to general radial potentials is challenging due to the lack of explicit basis functions analogous to Bessel functions. To overcome this difficulty, we consider the equation on a ball containing , without imposing boundary conditions, for a collection of values forming a fine discretisation of the interval in which eigenvalues are sought. By rewriting the problem in polar coordinates and applying a Fourier expansion with respect to the angular variable, we obtain a decoupled system of ordinary differential equations. These equations are solved numerically using a one-dimensional Finite Element Method, yielding a family of basis functions that are solutions of the equation on the ball and are independent of the domain . Dirichlet eigenvalues of are then approximated by minimising the boundary values on among linear combinations of the basis functions and identifying those values of for which the computed minimum is sufficiently small. The proposed method is highly memory-efficient compared to the standard Finite Element approach.
Speaker: Dr. Dragoș Manea is a mathematician specialising in mathematical analysis and applied mathematics. He holds a Master of Science degree from the University of Oxford and completed his PhD in Mathematics in 2025. He is currently a Research Assistant at the “Simion Stoilow” Institute of Mathematics of the Romanian Academy in Bucharest, Romania. His doctoral research focused on the theoretical and numerical analysis of evolutionary partial differential equations, with particular emphasis on deriving asymptotic results. In addition, he is interested in the numerical treatment of elliptic inverse and eigenvalue problems using non-standard approaches that avoid explicit meshing of the computational domain. Beyond PDE theory, his work also explores optimisation methods and their applications across a wide spectrum of problems, ranging from theoretical questions — such as the asymptotic analysis of solutions to the Schrödinger equation — to practical engineering applications, including the optimisation of urban traffic and aircraft trajectories.
Moderators: Dr. Pawel Gora, CEO of Quantum AI Foundation Quantum AI Foundation Dr. Sebastian Zajac, member of QPoland QPoland - QWorld