QSE Quantum Seminar: Benoit Vermersch and Robin Blume-Kohout

Please join us for the QSE Center Quantum Seminar with Benoit Vermersch from Quobly and UGA who will give the talk "Randomized measurements for large-scale quantum experiments" and Robin Blume-Kohout from Sandia National Labs who will give the talk "Assessing performance of logical operations with detector error models" on Friday April 24 from 11:30 to 13:30.
Location: GR B3 30

11:30-12:20 Benoit Vermersch
12:20-12:40: Pizza lunch
12:40-13:30: Robin Blume-Khout
All PhDs, postdocs, students, group leaders, and PIs are welcome to join us.

ABSTRACT:
1. "Randomized measurements for large-scale quantum experiments" -  Benoit Vermersch
The randomized measurements toolbox is now routinely used in quantum experiments to estimate fundamental quantum properties, such as entanglement [1].
While experimentalists appreciate the simplicity and robustness aspects of such measurement protocols, a challenge for theorists is to design strategies for overcoming statistical errors using "cheap" polynomial resources in system size.
In this context, I will present recent upgrades to the randomized measurements toolbox that address this challenge for large-scale quantum states that are relevant to the field of quantum simulation. In particular, I will discuss efficient protocols for measuring entanglement [2] and performing state tomography [3]. 
 
[1] A. Elben, S. T. Flammia, H.-Y. Huang, R. Kueng, J. Preskill, B. Vermersch, and P. Zoller, The Randomized Measurement Toolbox, Nat Rev Phys 5, 9 (2022).
[2] B. Vermersch, M. Ljubotina, J. I. Cirac, P. Zoller, M. Serbyn, and L. Piroli, Many-Body Entropies and Entanglement from Polynomially Many Local Measurements, Phys. Rev. X 14, 031035 (2024).
[3] M. Votto, M. Ljubotina, C. Lancien, J. Ignacio Cirac, P. Zoller, M. Serbyn, L. Piroli, B. Vermersch,  arXiv:2507.12550

2. "Assessing performance of logical operations with detector error models" - Robin Blume-Kohout 
Quantum computing is rapidly transitioning from the “NISQ” paradigm in which circuits and gates are executed directly on physical qubits to a fault tolerant “FTQC” paradigm in which circuits and gates are executed on encoded, error-corrected logical qubits.  We want to model errors in gates.  Logic gates on physical qubits are modeled by process matrices, derived from theory or estimated from tomography.  But describing logical gates on logical qubits demands a richer model — specifically, detector error models — that can describe QEC syndrome data.  I’ll introduce detector error models and summarize three recent papers in which we show how to estimate detector error models from data [https://arxiv.org/abs/2504.14643], how to simulate arbitrary small Markovian errors in Clifford circuits [https://arxiv.org/abs/2504.15128], and how to generate detector error models from arbitrary circuit-level Markovian errors [https://arxiv.org/abs/2603.18457].

BIOS:
Benoit Vermersch is an associate professor at the University of Grenoble Alpes, member of the LPMMC currently on leave in the quantum startup Quobly Research interests include implementations of quantum processing units with cold atoms, trapped ions, superconducting qubits; measurement protocols for entanglement-related quantities, out-of-time ordered correlators, topological invariants; many-body entanglement theory; quantum networks: Light-matter interfaces, quantum state transfer protocols, waveguide quantum electrodynamics; and tensor-network numerical methods: Matrix-Product-States and DMRG,TEBD related algorithms.
Robin Blume-Kohout was born on a kitchen table in the Alaska Bush almost (but not quite) 50 years ago.  Unfortunately, things went downhill thereafter.  He is now the founder and codirector of Sandia’s Quantum Performance Lab (QPL), where he and his fellow malcontents dream up new ways to assess and enhance the performance of quantum computers and their components.