by LISA ZYGA
In part (a), the three qubits (the magnetic nuclei of hydrogen, fluorine, and carbon) are shown, with the quantum information stored in the first qubit. In part (b), the quantum information has been transferred from the first qubit to the third qubit. IMAGE/Samal, et al. ©2011 American Physical Society.
In the classical world, information can be copied and deleted at will. In the quantum world, however, the conservation of quantum information means that information cannot be created nor destroyed. This concept stems from two fundamental theorems of quantum mechanics: the no-cloning theorem and the no-deleting theorem.
A third and related theorem, called the no-hiding theorem, addresses information loss in the quantum world. According to the no-hiding theorem, if information is missing from one system (which may happen when the system interacts with the environment), then the information is simply residing somewhere else in the Universe; in other words, the missing information cannot be hidden in the correlations between a system and its environment. Physicists Samuel L. Braunstein at the University of York, UK, and Arun K. Pati of the Harish-Chandra Research Institute, India, first proved the no-hiding theorem in 2007. Until now, however, the no-hiding theorem has been a purely theoretical concept.
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