Molecular Spin Qubits Impregnated in a Hexagonal Self-Ordered Mesoporous Silica

Quantum computing is one of the most important technologies in this century. As a class of qubit material in quantum computing devices, molecule-based electron spin clusters have attracted great interest from researchers in this field because of their advantages in design and synthesis. After years of development, the biggest challenge is still how to maintain the quantum coherence of enough qubits for a long time. To obtain a longer quantum coherence, in addition to the molecular design, the main method is to reduce the interference between spins by dilution. Mononuclear compounds can be magnetically diluted by diamagnetic ions. However, for polynuclear compounds, diamagnetic dilution possibly destroys their original electronic structure showing qubit properties. Therefore, magnetic dilution can only be achieved by dissolving crystals in solvents, and this approach clearly cannot be used in subsequent device fabrication either. In this work, we used DFT calculations to find the appropriate host and guest compounds, and then loaded a polynuclear compound [Cu3(L)3Cl3]Cl3·13H2O ([Cu3], L = 2,4,6-Tris(di-2-pyridylamine)-1,3,5-triazine, dipyatriz) into mesoporous silica (SBA15). The desired effect of diluting molecular spin in the solid state for the polynuclear system was successfully achieved. Electron paramagnetic resonance (EPR) shows that the decoherent times T2 are 281, 598, and 1298 ns for [Cu3], Cu3@SBA15, and Cu3@ACN ([Cu3]-CH3CN solution) at 4 K, respectively.