Quantum Dynamics and Decoherence of Spin-defects

Understanding the relation between the electronic structure of spin defects and their coherence properties is pivotal to optimizing the conditions for solid-state qubit applications. We develop frameworks and codes based on the generalized cluster expansion technique and spin Hamiltonians to investigate the effect of the nuclear spin bath on the coherence properties of spin defects, including studies at avoided crossing. Our calculations are validated by and integrated with experiments.

PyCCE: a Python package for CCE simulations

We develop PyCCE - an open-source python-based library for carrying out calculations of coherence times of spin defects based on the cluster correlation expansion (CCE) method.. This module is the first public implementation of the CCE method, available as an open-source package with high integration within the existing scientific Python ecosystem. The CCE method is one of the most widely used approaches to simulate the quantum decoherence dynamics of spin qubits in a finite spin bath and has been shown to reproduce the correct dynamics for a variety of physical realizations of spin qubits.

Coherence properties of spin-defects in molecules and solids

Using the cluster correlation expansion (CCE) and generalized cluster expansion methods we have provided quantitative predictions of spin qubits' dynamics in realistic media and for a variety of materials and systems, including 3D semiconductors and insulators (SiC, diamond and selected oxides), 2D materials (e.g. low-dimensional van der Waals solids) and molecular qubits. We have also integrated CCE calculations with experiment to implement a computationally guided growth process in nitrogen doped diamond films.

  • "Bath-limited dynamics of nuclear spins in solid-state spin platforms", Mykyta Onizhuk and Giulia Galli, Phys. Rev. B 108, 075306 (2023).
  • "Detecting spin bath polarization with quantum quench phase shifts of single spins in diamond", Paul C. Jerger, Yu-Xin Wang, Mykyta Onizhuk, Benjamin S. Soloway, Michael T. Solomon, Christopher Egerstrom, F. Joseph Heremans, Giulia Galli, Aashish A. Clerk, and David D. Awschalom, PRX Quantum 4, 040315 (2023).
  • "Enhancing spin coherence in optically addressable molecular qubits through host-matrix control", S. L. Bayliss, P. Deb, D. W. Laorenza, M. Onizhuk, G. Galli, D. E. Freedman, D. D. Awschalom, Phys. Rev. X 12, 031028 (2022).
  • "Generalized scaling of spin qubit coherence in over 12,000 host materials", Shun Kanai, F. Joseph Heremans, Hosung Seo, Gary Wolfowicz, Christopher P. Anderson, Sean E. Sullivan, Mykyta Onizhuk, Giulia Galli, David D. Awschalom, and Hideo Ohno, PNAS 119(15), e2121808119 (2022).
  • "Substrate-controlled Dynamics of Spin Qubits in Low Dimensional Van-der-Waals Materials", Mykyta Onizhuk and Giulia Galli, Appl. Phys. Lett. 118, 154003 (2021).
  • "Entanglement and control of single quantum memories in isotopically engineered silicon carbide", Alexandre Bourassa, Christopher P. Anderson, Kevin C. Miao, Mykyta Onizhuk, He Ma, Alexander L. Crook, Hiroshi Abe, Jawad Ul-Hassan, Takeshi Ohshima, Nguyen T. Son, Giulia Galli and David D. Awschalom, Nat. Mater. 19, 1319 (2020).
  • "PyZFS: A Python package for first-principles calculations of zero-field splitting tensors", He Ma, Marco Govoni and Giulia Galli, J. Open Source Softw. 5(47), 2160 (2020).
  • "All-electron density functional calculations for electron and nuclear spin interactions in molecules and solids", Krishnendu Gosh, He Ma, Vikram Gavini and Giulia Galli, Phys. Rev. Mater. 3, 043801 (2019).
  • "Quantum decoherence dynamics of divacancy spins in silicon carbide", Hosung Seo, Abram L. Falk, Paul V. Klimov, Kevin C. Miao, Giulia Galli, and David D. Awschalom, Nat. Commun. 7, 12935 (2016).
  • "Spin coherence in two dimensional materials", Meng Ye, Hosung Seo and Giulia Galli, Npj comput. mater. 5, 1-6 (2019).