Optical Spin Polarization of a Narrow-Linewidth Electron-Spin Qubit in a Chromophore/Stable-Radical System

Photoexcited organic chromophores appended to stable radicals can serve as qubit and/or qudit candidates for quantum information applications. 1,6,7,12-Tetra-(4-tert-butylphenoxy)-perylene-3,4 : 9,10-bis(dicarboximide) (tpPDI) linked to a partially deuterated alpha,gamma-bisdiphenylene-beta-phenylallyl radical (BDPA-d(16)) was synthesized and characterized by time-resolved optical and electron paramagnetic resonance (EPR) spectroscopies. Photoexcitation of tpPDI-BDPA-d(16) results in ultrafast radical-enhanced intersystem crossing to produce a quartet state (Q) followed by formation of a spin-polarized doublet ground state (D-0). Pulse-EPR experiments confirmed the spin multiplicity of Q and yielded coherence times of T-m=2.1 +/- 0.1 mu s and 2.8 +/- 0.2 mu s for Q and D-0, respectively. BDPA-d(16) eliminates the dominant H-1 hyperfine couplings, resulting in a single narrow line for both the Q and D-0 states, which enhances the spectral resolution needed for good qubit addressability.

Automated summary

Photoexcited organic chromophores combined with stable radicals can be used as candidates for quantum information applications. In this study, the synthesis and characterization of 1,6,7,12-Tetra-(4-tert-butylphenoxy)-perylene-3,4 : 9,10-bis(dicarboximide) (tpPDI) linked to a partially deuterated alpha,gamma-bisdiphenylene-beta-phenylallyl radical (BDPA-d(16)) were performed using time-resolved optical and electron paramagnetic resonance (EPR) spectroscopies. The results showed efficient generation of a quartet state (Q) followed by a spin-polarized doublet ground state (D-0) upon photoexcitation of tpPDI-BDPA-d(16).