Colour Centres in Diamond for quantum photonics and spintronics

Diamond is a material with enormous potential for next generation information technologies. Not only does pure diamond have many attractive physical properties such as hardness, chemical inertness, high thermal conductivity, and excellent optical transparency, but the defects found in diamond show remarkable 'quantum' properties similar to those of trapped single atoms, even at ambient temperature. The harnessing of these quantum properties into robust devices could revolutionise fields as diverse as telecommunications, healthcare, and computing. Our work on diamond focuses on two areas - studying the properties of single defects, known as colour centres, which emit light when stimulated, and controlling this emission by placing the colour centres into optical cavities.

Confocal microscope
Fig.1 A custom built scanning confocal microscope for measuring single colour centres in diamond

Figure 2 below (left) shows a false colour fluorescence image of a single nitrogen-vacancy colour centre recorded in our lab. It is remarkable to think that this is effectively an image of a single atom trapped in the diamond lattice. Our custom-built microscope will stay aligned for days at a time at low temperature, so we don't have to worry about losing the atom once we have found it. We can confirm that we are looking at a single quantum object by performing a photon correlation measurement (below, right), the pronounced dip at zero time delay showing that two photons are never emitted simultaneously.

Single NV centre Antibunching from single NV centre
Fig 2: (left) A 1 × 1 &mu m image showing fluorescence from a single nitrogen-vacancy centre in diamond, and (right) photon correlation signals from a single colour centre.

A major challenge in building devices that exploit the quantum properties of colour centres is to control the coupling of light into and out of the centres. Our approach to achieving this is to place a sub-micrometre sized piece of diamond containing a colour centre inside a high quality Fabry Perot microcavity. A schematic of this arrangement , and images of two films produced for our initial experiments by colleagues at the University of Melbourne, are shown in Fig. 3 below.

cavity sample
Fig 3: Diamond microstructures for cavity quantum photonic devices (SEM by Paolo Olivero).

Recent publications and presentations

F. Grazioso, B. R. Patton, P. Delaney, M. L. Markham, D. J. Twitchen, and J. M. Smith, Measurement of the full stress tensor in a crystal using photoluminescence from point defects: The example of nitrogen vacancy centers in diamond, Appl. Phys. Lett. 103, 101905 (2013).

D. Wildanger, B. R. Patton, H. Schill, L. Marseglia, J. P. Hadden, S. Knauer, A. Schönle, J. G. Rarity, J. L. O’Brien, S. W. Hell, and J. M. Smith, Solid Immersion facilitates fluorescence microscopy with nanometre resolution and sub-Angstrom emitter localization, Advanced Materials 24, OP309 (2012).

B. R. Patton, P. R. Dolan, F. Grazioso, M. B. Wincott, J. M. Smith, M. L. Markham, D. J. Twitchen, Y. Zhang, E. Gu, M. D. Dawson, B. A. Fairchild, A. D. Greentree and S. Prawer, Optical properties of single crystal diamond microfilms fabricated by ion implantation and lift-off processing, Diamond and Rel. Mat. 21, 16 (2012)

P. R. Dolan and J. M. Smith, Placing diamond colour centres into tunable optical microcavities, SBDD XVI, Hasselt, Belgium, February 21-23, 2011.

L. Marseglia, J. P. Hadden, A. C. Stanley-Clarke, J. P. Harrison, B. R. Patton, Y.-L. D. Ho, B. Naydenov, F. Jelezko, J. Meijer, P. R. Dolan, J. M. Smith, J. G. Rarity, and J. L. O'Brien, Nano-fabricated solid immersion lenses registered to single emitters in diamond, Appl. Phys. Lett. 98, 133107 (2011).

J. M Smith, F. Grazioso, B. R. Patton, P. R. Dolan, M. L. Markham and D. J. Twitchen, Optical properties of a single colour centre in diamond with a green zero phonon line, New J. Phys. 13, 045005 (2011).

J. M. Smith, Physics and applications of the zero phonon line in NV-, SBDD2010 diamond workshop, Hasselt, Belgium, February 22-24, 2010 (invited).

P. R. Dolan, B. R. Patton, and J M Smith Construction and analysis of arrayed, tuneable optical microcavities, Photon 10, Southampton, UK, August 24-27, 2010.

B. R. Patton, P. R. Dolan, F. Grazioso, B. Fairchild, P. Olivero, A. Greentree, S. Prawer, and J. M. Smith, Analysis of optical cavitation effects within diamond and construction and analysis of novel micro cavity arrays, SBDD XV, Hasselt diamond workshop, Hasselt, Belgium, February 22-24, 2010.

F. Grazioso, B. R. Patton, and J. M. Smith, A high stability beam-scanning confocal optical microscope for low temperature operation, Review of Scientific Instruments 81, 093705 (2010).

S. C. Benjamin, B. W. Lovett, and J. M. Smith, Prospects for measurement based quantum computing using solid state spins, Laser & Photonics Reviews 3, p.556 (2009).

B. R. Patton, P. R. Dolan, F. Grazioso, J. M. Smith, B. Fairchild, P. Olivero, A. Greentree, and S. Prawer, Diamond microstructures for optical cavity based devices, DeBeers Diamond Conference, Warwick University, June 30, 2009.

B. R. Patton, F. Grazioso, P. R. Dolan, J. M. Smith, B. Fairchild, P. Olivero, A. Greentree, and S. Prawer, Optical properties of microstructured diamond, Diamond 2009, Athens, September 6-10, 2009.

B. A. Fairchild, P. Olivero, A. D. Greentree, F. Waldermann, R. A. Taylor, J. M. Smith, S. Rubanov, S. Huntington, B. Gibson, D. N. Jamieson, and S. Prawer, Fabrication of ultra thin membranes from single crystal diamond for photonic and NEMS applications, Advanced Materials 20, p4793 (2008).

F. Grazioso, B. R. Patton, J. M. Smith, and D. J .Twitchen, Luminsecnece characteristics of NV centres in ultrapure diamond, DeBeers diamond conference, St Catherine's College Oxford, July 5-8, 2008.

J. M. Smith, B. R. Patton, and F. Grazioso, Towards measurement-based quantum computation using solid state spins, SPIE Photonics West Conference Proceedings, ADVANCED CONCEPTS IN QUANTUM COMPUTING, MEMORY, AND COMMUNICATION 6903, p.9030, San Jose, January, 2008.

B. Patton, F. Grazioso, and J. M. Smith, Towards measurement-based entanglement of single NV centres in diamond, Measurement Based Quantum Computing, St John's College, Oxford, March 18-21, 2007.

J. M. Smith, Prospects for measurement-based quantum computing using nitrogen-vacancy centres in diamond, QCV Quantum Diamond, Melbourne, Australia, July 16-19, 2007.