Mattias Fitzpatrick

Overview

Mattias Fitzpatrick graduated with a bachelor's in physics and mathematics from Middlebury College, and a PhD in electrical engineering (applied physics) from Princeton University where he worked with Professor Andrew Houck on superconducting circuits. He then received an Intelligence Community (IC) postdoctoral fellowship to work on quantum sensing in the lab of Nathalie de Leon at Princeton University. After his postdoctoral fellowship, he went on to work on quantum computation at IBM's Thomas J. Watson Research Center. His current research focuses on quantum engineering and quantum sensing using superconducting circuits. Outside of the lab and classroom he enjoys cooking, backpacking, playing soccer, skiing, and generally spending time in the great outdoors.

Research Interests

Quantum computing; quantum engineering; quantum sensing; quantum information; artificial intelligence (AI)

Education

• BA, Physics / Minor in Mathematics, Middlebury College 2013
• PhD, Electrical Engineering (Applied Physics), Princeton University 2019

Awards

• Intelligence Community (IC) Postdoctoral Fellowship
• Bede Liu Best Dissertation Award in Electrical Engineering
• Princeton University Distinguished Teaching Award
• DARPA Young Faculty Award

Professional Activities

• Reviewer, NPJ Quantum Information
• Reviewer, Referee for Nature Physics
• Reviewer, Science
• Reviewer, Physical Review Letters
• Reviewer, Nature Quantum Information
• Reviewer, Physical Review X Quantum

Research Projects

• Non-Hermitian quantum sensing

  Non-Hermitian quantum sensing

  Non-Hermitian quantum sensing explores how engineered gain, loss, and complex coupling can be used as new resources for quantum and quantum-inspired sensing. Our work centers on room-temperature YIG ferrimagnetic oscillators that act as state-of-the-art AC magnetometers: they encode magnetic fields in a collective spin precession and microwave frequency, but their present performance is limited by entirely classical noise mechanisms in the feedback and readout chain. We combine these YIG-based sensors with tunable cavity–magnon platforms in which non-Hermitian effects—such as exceptional points, transmission peak degeneracies, and synthetic gauge fields—can be realized and controlled. By integrating these elements into programmable microwave networks, we tailor effective linewidths, dissipation, and coupling phases, and directly connect radio-frequency control parameters to spectral response and noise. This project uses non-Hermitian physics to probe and overcome classical noise limitations in otherwise quantum-inspired sensors, with the goal of improving frequency stability and magnetic-field sensitivity in compact, room-temperature devices.

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• Quantum two-level-system defect spectroscopy

  Quantum two-level-system defect spectroscopy

  Quantum computing has the potential to tackle problems that are difficult for conventional computers, such as designing new materials, simulating complex molecules, and optimizing large-scale systems. Unlike classical bits, which are either 0 or 1, quantum bits (qubits) can exist in a superposition of states—a delicate condition that must be preserved for reliable computation. In solid-state platforms such as superconducting circuits and quantum dots, two-level system (TLS) defects naturally occur in thin insulating and amorphous layers, leading to loss of coherence.

  We have developed broadband cryogenic transient dielectric spectroscopy (BCTDS) to study these defects directly. By applying high-power microwave pulses, BCTDS can probe the coherent dynamics of TLS ensembles, extract their spectral features and frequency distribution within a given bandwidth, and operate without the need for a fully-fabricated quantum device. This method also provides a versatile platform for studying driven, dissipative many-body quantum dynamics in disordered systems, and for characterizing and mitigating sources of decoherence in quantum materials.

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Selected Publications

• Carney AS, Salcedo‑Gallo JS, Bedkihal SK, Fitzpatrick M. (2025) "Unification of Exceptional Points and Transmission Peak Degeneracies in a Highly Tunable Magnon‑Photon Dimer." arXiv. 2506.09141.
• Salcedo‑Gallo JS, Burgelman M, Flynn VP, et al. (2025) "Demonstration of a tunable non‑Hermitian nonlinear microwave dimer." Nature Communications. 16: 7193.
• Wang Q, Salcedo‑Gallo JS, Bedkihal S, Xia T, Olszewski MW, Fatemi V, Fitzpatrick M. (2025) "Spectroscopy and coherent control of two‑level system defect ensembles using a broadband 3D waveguide." Materials for Quantum Technology. 5(4): 045201.
• Wang Q, Gómez SM, Salcedo‑Gallo JS, Leibovitz R, Freeman J, Agnew SA, et al. (2025) "Evidence of memory effects in the dynamics of two‑level system defect ensembles using broadband, cryogenic transient dielectric spectroscopy." arXiv. 2505.18263.
• Dwyer BL, Rodgers LV, Urbach EK, Bluvstein D, Sangtawesin S, Zhou H, Nassab Y, Fitzpatrick M, Yuan Z, Greve KD, Peterson EL, Chou J, Gali Á, Dobrovitski VV, Lukin MD, Leon NP. (2022) "Probing Spin Dynamics on Diamond Surfaces Using a Single Quantum Sensor." Physical Review X Quantum. 3: 040328.
• Rovny J, Yuan Z, Fitzpatrick M, Abdalla AI, Futamura L, Fox C, Cambria MC, Kolkowitz S, Leon NP. (2022) "Nanoscale Covariance Magnetometry with Diamond Quantum Sensors." Science. 378(6626).
• Fitzpatrick M, Sundaresan N, Santos R, Lundgren R, Sivarajah P, Miloshi D, Foss-Feig M, Koch J, Garg M, Childs AM, Frunzio L, Schoelkopf RJ, Girvin SM, Bowan C, Refael G, Houck AA. (2021) "Observation of a Prethermal Discrete Time Crystal." Physical Review X. 11(1): 011047.
• Place APM, Rodgers LVH, Mundada P, Smitham BM, Fitzpatrick M, et al. (2021) "New Material Platform for Superconducting Transmon Qubits with Coherence Times Exceeding 0.3 Milliseconds." Nature Communications. 12(1): 1–6.
• Kollár AJ, Fitzpatrick M, Sarnak P, Houck AA. (2020) "Line-Graph Lattices: Euclidean and Non-Euclidean Flat Bands, and Implementations in Circuit Quantum Electrodynamics." Communications in Mathematical Physics. 376(3): 1909–1956.
• Kollár AJ, Fitzpatrick M, Houck AA. (2019) "Hyperbolic Lattices in Circuit Quantum Electrodynamics." Nature. 571(7763): 45–50.
• Fitzpatrick M, Sundaresan NM, Li ACY, Koch J, Houck AA. (2017) "Observation of a Dissipative Phase Transition in a One-Dimensional Circuit QED Lattice." Physical Review X. 7(1): 011016.

News

New Study Paves the Way for Better Control of Interactions Between Oscillators
Aug 14, 2025

Dartmouth Engineering Professor Receives DARPA Young Faculty Award
Oct 03, 2023

Introducing Dartmouth's New Faculty Members
Mar 15, 2023

Dartmouth Engineering Welcomes Three New Faculty
Dec 01, 2022