Quantum process tomography of entangled photons as a probe of intermediates of singlet fission in a tetracene derivative Ajay Ram Srimath Kandada, 1, a) Ilaria-Bargigia, 2, a) Eric. R. Bittner, 3 and Carlos Silva 2, 4, 5, b) 1) Center for Nano Science and Technology@PoliMi, Istituto Italiano di Tecnologia, via Giovanni Pascoli 70/3, 20133 Milano, Italy 2) School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive NW, Atlanta, Georgia 30332, United States 3) Department of Chemistry, University of Houston, Houston, Texas 77204, United States 4) School of Physics, Georgia Institute of Technology, 837 State Street NW, Atlanta, Georgia 30332, United States 5) School of Materials Science and Engineering, Georgia Institute of Technology, North Avenue, Atlanta, Georgia 30332, United States (Dated: 26 January 2022) Spin-entaglement has been proposed and extensively used in the case of correlated triplet pairs which are intermediate states in singlet fission process in select organic semiconductors. Here, we employ quantum process tomography of polarization en- tangled photon-pairs resonant with the excited state absorption of these states to investigate the nature of the inherent quantum correlations and to explore for an unambiguous proof for the existence of exciton entanglement. a) These authors contributed equally to this work. b) E-mail address: carlos.silva@gatech.edu 1 arXiv:1909.12869v1 [physics.chem-ph] 27 Sep 2019