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Diamond Qubits for Sensing in Biology

Professor Lloyd C. L. Hollenberg

Centre of Excellence for Quantum Computation and Communication Technology, School of Physics, University of Melbourne

3:30 pm Friday, 7 October 2011, EN101 Lecture Theatre (EN Building), Hawthorn.

The fundamental building blocks of a quantum computer are qubits – individually controlled two-level quantum systems. As the march towards quantum computing continues apace, the quantum control of qubit systems has been achieved in a range of physical platforms – electronic, photonic and atomic – together with a deep understanding of their environmental interactions. In this talk we will report on the demonstration of a qubit system as a nanoscale probe [1], where the qubit is deliberately exposed to the worst possible, but most interesting, environment – room temperature biology. The nitrogen-vacancy (NV) defect centre in diamond represents an ideal single spin qubit for use in biology as a nanoscale magnetometer probe. It possesses a broad absorption band from 512-560 nm, sustained fluorescence from 630-750 nm, is chemically inert and bio-compatible and most importantly has relatively long quantum coherence at room temperature. These defect centres have been used as highly stable fluorescence beacons to track the position and diffusion of diamond nano-crystals in vitro[2,3] and in vivo[4].  Recent experimental demonstrations[5] of nanomagnetometry using these single spin systems create opportunities for new applications in biology [6]. We explore the viability of diamond-based nanomagnetometry bio-applications by performing the full suite of quantum control and measurement protocols on NV-nanodiamonds in a living human HeLa cell, and demonstrate the enhancements that the quantum properties of the NV qubit enable for orientation tracking in the intra-cellular context [1].

1.             L. P. McGuinness et al., Nature Nanotechnology 6 358363 (2011)
2.             F. Neugart et al. Nano Letters 7 3588 (2007) 
3.             Y.R. Chang et al. Nature Nanotechnology 3 284 (2008)
4.             N. Mohan et al. Nano Letters 10 3692 (2010)
5.             J. Maze et al. Nature 455 644 (2008), G. Balasubramanian et al. Nature 455 648 (2008)
6.             L. Hall et al. Proceedings of the National Academy of Sciences 107 18777 (2010)

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