Takahashi Group
Quantum Sensing & Quantum Dynamics
Quantum Sensing & Quantum Dynamics
We are an interdisciplinary experimental research group overlapping in the areas of Physical Chemistry (Phys Chem), Quantum Information Science (QIS) and Condensed Matter Physics (CMP). We all know quantum mechanics (QM) can explain electronic states of atoms and molecules. QIP is fascinating and has the potential to advance our technology, but QM effect is often hidden in noise and is difficult to see directly. Can we control/manipulate quantum phenomena? How can we build a desired quantum system? How quantum technology can be used to uncover molecular and materials properties? Can a QM-assisted measurement outperform a conventional measurement? We are interested to overcome those challenges and to solve scientific puzzles using experiment with unique instrumentation and intuitive theory.
We introduce a couple of recent research highlights here.
A. Gurgenidze, A. Krylov and S. Takahashi, J. Chem. Phys. Lett. 16, 2906 (2025)
We report quantum chemistry calculations of g tensors and hyperfine coupling tensors (A tensors) for the nitroxide radical spin label in the pressure range of 0–15 GPa. The hydrostatic pressure causes structural changes, which, in turn, result in linear changes of the g and A tensors. The observed linear dependence of the g and A tensors suggests that these quantities can serve as reporters of local pressure in complex environments. The corresponding simulated EPR spectra at 9 and 230 GHz reveal that the changes of the EPR spectrum are more pronounced in the former. Our results indicate that the computational approach can address the challenge of determining magnetic spin parameters under extreme conditions, such as under high hydrostatic pressure.
Our image has been featured as cover art!
Demonstration of NV-detected 13C NMR at 4.2 T
Yuhang Ren, Cooper Selco, Dylan Kawashiri, Michael Coumans, Benjamin Fortman, Louis-S. Bouchard, Karoly Holczer, and Susumu Takahashi, Phys. Rev. B 108, 045421 (2023)
The nitrogen-vacancy (NV) center in diamond has enabled studies of nanoscale nuclear magnetic resonance (NMR) and electron paramagnetic resonance with high sensitivity in small sample volumes. Most NV-detected NMR (NV-NMR) experiments are performed at low magnetic fields. While low fields are useful in many applications, high-field NV-NMR with fine spectral resolution, high signal sensitivity, and the capability to observe a wider range of nuclei is advantageous for surface detection, microfluidic, and condensed matter studies aimed at probing micro- and nanoscale features. However, only a handful of experiments above 1 T were reported. Herein, we report 13C NV-NMR spectroscopy at 4.2 T, where the NV Larmor frequency is 115 GHz. Using an electron-nuclear double resonance technique, we successfully detect NV-NMR of two diamond samples.
A. Pambukhchyan, S. Weng, I. Aravind, S. B Cronin, S. Takahashi, Mater. Quantum. Technol. 3 035005 (2023).
Nitrogen-vacancy (NV) and silicon-vacancy (SiV) color defects in diamond are promising systems for applications in quantum technology. The NV and SiV centers have multiple charge states, and their charge states have different electronic, optical and spin properties. For the NV centers, most investigations for quantum sensing applications are targeted on the negatively charged NV (NV−), and it is important for the NV centers to be in the NV− state. However, it is known that the NV centers are converted to the neutrally charged state (NV0) under laser excitation. An energetically favorable charge state for the NV and SiV centers depends on their local environments. It is essential to understand and control the charge state dynamics for their quantum applications. In this work, we discuss the charge state dynamics of NV and SiV centers under high-voltage nanosecond pulse discharges.
Contact information
Takahashi lab
Department of Chemistry
840 Downey Way, Stabler Hall
University of Southern California
Los Angeles, CA 90089-0744
susumuta at usc dot edu