Letter abstract
Nature Physics 2, 40 - 43 (2006)
doi:10.1038/nphys192
Subject Categories: Atomic and molecular physics | Information theory and computation | Quantum physics
Bang–bang control of fullerene qubits using ultrafast phase gates
John J. L. Morton1,2, Alexei M. Tyryshkin3, Arzhang Ardavan2, Simon C. Benjamin1, Kyriakos Porfyrakis1, S. A. Lyon3 and G. Andrew D. Briggs1
Quantum mechanics permits an entity, such as an atom, to exist in a superposition of multiple states simultaneously. Quantum information processing (QIP) harnesses this profound phenomenon to manipulate information in radically new ways1. A fundamental challenge in all QIP technologies is the corruption of superposition in a quantum bit (qubit) through interaction with its environment. Quantum bang–bang control provides a solution by repeatedly applying 'kicks' to a qubit2, thus disrupting an environmental interaction. However, the speed and precision required for the kick operations has presented an obstacle to experimental realization. Here we demonstrate a phase gate of unprecedented speed3, 4 on a nuclear spin qubit in a fullerene molecule, and use it to bang–bang decouple the qubit from a strong environmental interaction. We can thus trap the qubit in closed cycles on the Bloch sphere, or lock it in a given state for an arbitrary period. Our procedure uses operations on a second qubit, an electron spin, to generate an arbitrary phase on the nuclear qubit. We anticipate that the approach will be important for QIP technologies, especially at the molecular scale where other strategies, such as electrode switching, are unfeasible.
- Department of Materials, Oxford University, Oxford OX1 3PH, UK
- Clarendon Laboratory, Department of Physics, Oxford University, Oxford OX1 3PU, UK
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
Correspondence to: John J. L. Morton1,2 e-mail: john.morton@sjc.ox.ac.uk
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