Entanglement of Spin-Pair Qubits with Intrinsic Dephasing Times Exceeding a Minute

H. P. Bartling, M. H. Abobeih, B. Pingault, M. J. Degen, S. J.H. Loenen, C. E. Bradley, J. Randall, M. Markham, D. J. Twitchen, T. H. Taminiau*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

Understanding and protecting the coherence of individual quantum systems is a central challenge in quantum science and technology. Over the past decades, a rich variety of methods to extend coherence have been developed. A complementary approach is to look for naturally occurring systems that are inherently protected against decoherence. Here, we show that pairs of identical nuclear spins in solids form intrinsically long-lived qubits. We study three carbon-13 pairs in diamond and realize high-fidelity measurements of their quantum states using a single nitrogen-vacancy center in their vicinity. We then reveal that the spin pairs are robust to external perturbations due to a combination of three phenomena: a decoherence-free subspace, a clock transition, and a variant on motional narrowing. The resulting inhomogeneous dephasing time is T2∗=1.9(3) min, the longest reported for individually controlled qubits. Finally, we develop complete control and realize an entangled state between two spin pairs through projective parity measurements. These long-lived qubits are abundantly present in diamond and other solids and provide new opportunities for ancilla-enhanced quantum sensing and for robust memory qubits for quantum networks.

Original languageEnglish
Article number011048
Number of pages15
JournalPhysical Review X
Volume12
Issue number1
DOIs
Publication statusPublished - 2022

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