Entanglement in a solid-state spin ensemble

Stephanie Simmons, Richard M. Brown, Helge Riemann, Nikolai V. Abrosimov, Peter Becker, Hans Joachim Pohl, Mike L.W. Thewalt, Kohei M. Itoh, John J.L. Morton

Research output: Contribution to journalArticlepeer-review

126 Citations (Scopus)


Entanglement is the quintessential quantum phenomenon. It is a necessary ingredient in most emerging quantum technologies, including quantum repeaters, quantum information processing and the strongest forms of quantum cryptography. Spin ensembles, such as those used in liquid-state nuclear magnetic resonance, have been important for the development of quantum control methods. However, these demonstrations contain no entanglement and ultimately constitute classical simulations of quantum algorithms. Here we report the on-demand generation of entanglement between an ensemble of electron and nuclear spins in isotopically engineered, phosphorus-doped silicon. We combined high-field (3.4T), low-temperature (2.9K) electron spin resonance with hyperpolarization of the 31 P nuclear spin to obtain an initial state of sufficient purity to create a non-classical, inseparable state. The state was verified using density matrix tomography based on geometric phase gates, and had a fidelity of 98% relative to the ideal state at this field and temperature. The entanglement operation was performed simultaneously, with high fidelity, on 10 10 spin pairs; this fulfils one of the essential requirements for a silicon-based quantum information processor.

Original languageEnglish
Pages (from-to)69-72
Number of pages4
Issue number7332
Publication statusPublished - 2011 Feb 3

ASJC Scopus subject areas

  • General


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