Gergo Thiering1,2,Matt Cambria3,Shimon Kolkowitz3,Ishita Kemeny3,Ariel Norambuena4,Yanfei Li3,Aedan Gardill3,Hossein Dinani4,Vincenzo Lordi5,Jerónimo Maze6,Adam Gali1,2
Wigner Research Centre1,Budapest University of Technology and Economics2,University of Wisconsin-Madison3,Universidad Mayor4,Lawrence Livermore National Laboratory5,Pontificia Universidad Católica de Chile6
Gergo Thiering1,2,Matt Cambria3,Shimon Kolkowitz3,Ishita Kemeny3,Ariel Norambuena4,Yanfei Li3,Aedan Gardill3,Hossein Dinani4,Vincenzo Lordi5,Jerónimo Maze6,Adam Gali1,2
Wigner Research Centre1,Budapest University of Technology and Economics2,University of Wisconsin-Madison3,Universidad Mayor4,Lawrence Livermore National Laboratory5,Pontificia Universidad Católica de Chile6
Certain defects in diamond are promising candidates as building blocks for quantum information processing. In particular, the nitrogen-vacancy (NV) center in diamond has become one of the leading solid-state qubit contenders to its favorable properties. One of the most remarkable properties is its long spin coherence time: it can reach 1 ms at room temperature and can exceed seconds at cryogenic temperatures. In our present work, we will describe the spin-lattice interaction between S=1 electronic spin of NV center and the lattice phonons by means of density functional theory and experiments for a temperature range between 9 to 474 K in high-purity diamond samples. Spin-lattice relaxation is an intrinsic property of the host material and the defect that can be less obviously engineered like the coherence times by isotope engineering of the host material. As T<sub>1</sub> time is an ultimate limit for the spin coherence, deep insight about the spin-lattice relaxation processes is necessary for control of the NV center and understand this process for akin color centers in solids. Here, we review the first order and second order (Raman) spin-phonon relaxation processes acting between NV center’s |ms = 0)↔|ms = +1)↔|ms = -1) spin states. To our best knowledge, only the ultralow temperature regime below 1 K has been discussed for NV center at ab-initio level, to date [1]. In this paper, we discuss the second order Raman transitions that dominate relaxation at high temperatures which is in stark contrast to the case of small molecules [2]. By invoking the ab-initio spin-phonon spectral functions, we propose a novel analytic model in which NV spin-phonon relaxation is characterized by interactions with two distinct groups of quasilocalized phonons which can be described as a double Orbach-process. In summary, we developed an ab-initio framework that can predict the spin-relaxation times and associated limit of coherence times for any spin-1 qubit center in diamond and related materials.<br/>A. G. acknowledges support from the National Research Development and Innovation Office of Hungary within the Quantum Technology National Excellence Program (Project Contract No. 2017-1.2.1-NKP-2017-00001) and the National Excellence Program (Project No. KKP129866) and the Quantum Information National Laboratory sponsored via the Ministry of Innovation and Technology of Hungary, and the European Commission of H2020 ASTERIQS project (Grant No. 820394). We thank the National Information Infrastructure Development Program for the high-performance computing resources in Hungary. G. T. were supported by the János Bolyai Research Scholarship of the Hungarian Academy of Sciences. The acknowledge the high-performance computational resources provided by KIFÜ (Governmental Agency for IT Development) institute of Hungary. Part of this work was performed under the auspices of US DOE by LLNL under Contract DE-AC52-07NA27344.