Coherence and entanglement of inherently long-lived spin pairs in diamond

Abstract

Understanding and protecting the coherence of individual quantum systems is a central challenge in quantum science and technology. Over the last 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 quantum systems. We study three carbon-13 pairs in diamond and realize high-fidelity measurements of their quantum states using a single NV center in their vicinity. We then reveal that the spin pairs are robust to external perturbations due to a unique combination of three phenomena: a clock transition, a decoherence-free subspace, and a variant on motional narrowing. The resulting inhomogeneous dephasing time is $T_2^{\ast }=1.9(3)$ minutes, the longest reported for individually controlled qubits. Finally, we develop complete control and realize an entangled state between two spin-pair qubits through projective parity measurements. These long-lived qubits are abundantly present in diamond and other solids, and provide new opportunities for quantum sensing, quantum information processing, and quantum networks.

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• Entanglement detection
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• Decoherence of Nuclear Spins in the Proximity of Nitrogen Vacancy Centers in Diamond
• Dynamical quantum phase transition in diamond: applications in quantum metrology
• Performance of quantum registers in diamond in the presence of spin impurities
• Control of an environmental spin defect beyond the coherence limit of a central spin
• Nuclear Spin Engineering for Quantum Information Science
• Multidimensional spectroscopy of nuclear spin clusters in diamond
• A many-body singlet prepared by a central spin qubit
• Improved Electron-Nuclear Quantum Gates for Spin Sensing and Control
• Enhancing qubit readout with Bayesian Learning
• High-fidelity dimer excitations using quantum hardware
• Qubit-environment entanglement in time-dependent pure dephasing
• Transition metal ion ensembles in crystals as solid-state coherent spin-photon interfaces: The case of nickel in magnesium oxide
• Quantum-network nodes with real-time noise mitigation using spectator qubits
• Controlling discrete time crystals via single-site operations in zero-field diamond quantum simulators
• Quantifying electron-nuclear spin entanglement dynamics in central-spin systems using one-tangles
• Suppression of coherent errors during entangling operations in NV centers in diamond