Spectroscopy and Coherent Control of Two-Level System Defect Ensembles Using a Broadband 3D Waveguide: Theory and Model
ORAL
Abstract
Two-level system (TLS) defects in amorphous materials critically influence coherence, stability, and performance in quantum technologies. While individual TLSs can be probed with narrowband devices such as qubits or resonators, their collective dynamics remain difficult to access. We address this challenge with our recently developed Broadband Cryogenic Transient Dielectric Spectroscopy (BCTDS) technique, which enables modular measurements of TLS ensembles without requiring full device fabrication. BCTDS reveals interference effects, memory-dependent dynamics, and dressed-state evolution within the TLS bath. In Part II, we present a driven minimal spin model with dipole–dipole interactions, developed to interpret the results. The model qualitatively reproduces the key experimental features, including amplitude- and phase-controlled relaxation dynamics and the corresponding spectral signatures of the TLS defects ensembles.
*Startup funds from the Thayer School of Engineering, Dartmouth College, supported this work. We gratefully acknowledge support from DARPA Young Faculty Award No. D23AP00192. M.O. and V.F. acknowledge startup funds from Cornell University. Partial funding for shared facilities used in this prototype was provided by the Microelectronics Commons Program, a DoD initiative, under award number N00164-23-9-G061.
–
Publication:* Evidence of Memory Effects in the Dynamics of Two-Level System Defect Ensembles Using Broadband, Cryogenic Transient Dielectric Spectroscopy, 2025, https://arxiv.org/pdf/2505.18263 * Spectroscopy and Coherent Control of Two-Level System Defect Ensembles Using a Broadband 3D Waveguide, under preparation, 2025.
