Passcode: 862998

Quantum technology, including quantum computing, sensing, and communication, is one of the most revolutionary technologies of our time. Among quantum systems, solid-state qubit systems, such as a nitrogen-vacancy (NV) center in diamond, are promising for applications of quantum sensing and communication. In this talk, I will present research projects on solid-state qubits at USC. In the first part of the talk, I discuss the development of nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) techniques enhanced by the NV center in diamond [1, 2]. The NV center is a fluorescent impurity center found in the diamond lattice. The NV center is one of the most promising quantum sensors because of its unique properties. The NV center is an excellent quantum sensor. In the second part, I will discuss the electrical control of solid-state qubits. In particular, the control of charge states of NV and Silicon-vacancy (SiV) centers in diamond will be presented. Defect and impurity centers in diamond contain multiple charge states. A notable example is a negatively and neutrally charged NV center in diamond, whose optical and spin properties are very different. Recent DFT studies show that an energetically favorable charge state can be controlled by adjusting the chemical potential of the diamond sample, which often requires significant materials engineering. Our research shows an alternative approach for the control of charge states with the use of nanosecond high-voltage pulse discharges [3, 4].

References [1] Yuhang Ren, Cooper Selco, Dylan Kawashiri, Michael Coumans, Benjamin Fortman, Louis S. Bouchard, Karoly Holczer and Susumu Takahashi, Phys. Rev. B, 108, 045421 (2023). [2] Yifan Song, Nabiha Hasan and Susumu Takahashi, Phys. Rev. Applied 24, 054057 (2025). [3] A. Pambukhchyan, S. Weng, I. Aravind, S. B. Cronin and S. Takahashi, Mater. Quantum. Technol. 3, 035005 (2023). [4] H Highland, Y Song, S Ilkhani, E Song, S Weng, S B. Cronin and S Takahashi, Adv. Opt. Mater. 0:e03740 (2026).