Experimental Protection of the Spin Coherence of a Molecular Qubit Exceeding a MillisecondSupported by the National Key R&D Program of China (Grant Nos. 2018YFA0306600 and 2016YFB0501603), the Chinese Academy of Sciences (Grant Nos. GJJSTD20170001, QYZDY-SSW-SLH004, and QYZDB-SSW-SLH005), and Anhui Initiative in Quantum Information Technologies (Grant No. AHY050000). X.R. thanks the Youth Innovation Promotion Association of Chinese Academy of Sciences for

Abstract

Molecular qubits are promising as they can benefit from tailoring and versatile design of chemistry. It is essential to reduce the decoherence of molecular qubits caused by their interactions with the environment. Herein the dynamical decoupling (DD) technique is utilized to combat such decoherence. The coherence time for a transition-metal complex (PPh4)2[Cu(mnt)2] is prolonged from 6.8 μs to 1.4 ms. The ratio of the coherence time and the length of π/2 pulse, defined as the single qubit figure of merit (Q M), reaches 1.4 × 105, which is 40 times greater than what previously reported for this molecule. Our results show that molecular qubits, with milliseconds coherence time, are promising candidates for quantum information processing.