Quantum Computing Hardware Design
At present, we develop theoretical models and design tools for superconducting quantum processors. Our focus is on capturing realistic processor physics in ways that inform next-generation qubit design and operation.
Many-Body Quantum Dynamics in Quantum Processors
We study how collective many-body dynamics emerges as superconducting processors scale to larger numbers of coupled qubits. Using tools from Floquet theory and random matrix theory, we characterize driven, interacting dynamics in realistic architectures and identify constraints on control and performance, including drive-induced errors.
Protected Qubits
We study mechanisms for building qubits that are intrinsically robust to noise. In particular, we investigate encodings with disjoint support that reduce sensitivity to local error processes, and we analyze when such protection can remain compatible with practical control and readout.
Semiclassical Analysis of Superconducting Circuits
We develop semiclassical methods for analyzing superconducting circuits as engineered nonlinear oscillators governed by Josephson physics. These approaches provide interpretable, quantitative insight in regimes where fully quantum modeling is possible but less transparent and more computationally demanding.
Selected Publications
Systematic Construction of Time-Dependent Hamiltonians for Microwave-Driven Josephson Circuits
Y. Lu, T. Zhao, A. Vallières, K.C. Smith, D. Weiss, X. You, Y. Zhang, S. Ganjam, A. Maiti, J.W.O. Garmon, S. Mundhada, Z. Huang, I. Mondragon-Shem, S.M. Girvin, J. Koch, R.J. Schoelkopf
arXiv:2512.20743 (2025)
Exceeding the Parametric Drive Strength Threshold in Nonlinear Circuits
M. Xia, C. Lledó, M. Capocci, J. Repicky, B. D’Anjou, I. Mondragon-Shem, R. Kaufman, J. Koch, A. Blais, M. Hatridge
arXiv:2506.03456 (2025)
Computer-aided quantization and numerical analysis of superconducting circuits
S.P. Chitta, T. Zhao, Z. Huang, I. Mondragon-Shem, J. Koch
New Journal of Physics 24, 103020 (2022)
Local imaging of diamagnetism in proximity-coupled niobium nanoisland arrays on gold thin films
L. Bishop-Van Horn, I.P. Zhang, E.N. Waite, I. Mondragon-Shem, S. Jensen, J. Oh, T. Lippman, M. Durkin, T.L. Hughes, N. Mason, K.A. Moler, I. Sochnikov
Phys. Rev. B 106, 054521 (2022)