Generating electron spin qubit in metal-organic frameworks via spontaneous hydrolysis

Abstract

Qubit, as the basic unit of quantum operations, has at least two quantum states for superposition. Diamond itself has no superimposable quantum states, but after injecting N atoms, the resulted nitrogen-vacancy centers form excellent-performance qubits. For the same purpose, we can also obtain qubits by modifying the matrix without effective quantum states. HKUST-1 ({Cu3(BTC)2(H2O)3}, BTC = 1,3,5-benzene-tricarboxylate) with S = 0 ground state is electron paramagnetic resonance (EPR) silent, so it is not a qubit candidate. However, the spontaneously hydrolyzed HKUST-1 produces dilute uncoupled CuII ions with S = 1/2. In this paper, we utilized the hydrolysis products of HKUST-1 to obtain qubits and assembled a core-shell structural HKUST-1@ZIF-8 by ZIF-8 ({Zn(mim)2}, mim = 2-methylimidazole) coated over HKUST-1 for controlling the hydrolysis. The experimental results clearly show that the qubits come from hydrolyzed CuII ions. Furthermore, the dilute uncoupled CuII ions in this assembly can effectively reduce the decoherence of qubits. The EPR studies show that the T2 of this compound is 1067 ns at 10 K.