Resonant enhancement of the zero-phonon emission from a colour centre in a diamond cavity

Integrated quantum photonic technologies are key for future applications in quantum information1, (O'Brien et al. in Nature Photon. 3:687, 2009), ultralow-power opto-electronics (Mabuchi in Phys. Rev. A 80:045802, 2009) and sensing (Balasubramanian in Nature 455:648, 2008). As individual quantum bits, nitrogen-vacancy centres in diamond are among the most promising solid-state systems identified to date, because of their long-lived electron and nuclear spin coherence and capability for individual optical initialization, readout and information storage (Jelezko in Phys. Rev. Lett. 93:130501, 2004, Balasubramanian in Nature Mater. 8:383, 2009, Santori in Phys. Rev. Lett. 97:247401, 2006, Buckley et al. in Science 330:1212, 2010, Gurudev Dutt in Science 316:1312, 2007). The major outstanding hurdle lies in interconnecting many nitrogen vacancies for large-scale computation. One of the most promising approaches in this regard is to couple them to optical resonators, which can be further interconnected in a photonic network (Cabrillo et al. in Phys. Rev. A 59:1025, 1999, Childress et al. in Phys. Rev. A 72:052330, 2005, Togan in Nature 466:730, 2010). Here, we demonstrate coupling of the zero-phonon line of individual nitrogen vacancies to the modes of microring resonators fabricated in single-crystal diamond. Zero-phonon line enhancement by more than a factor of 10 is estimated from lifetime measurements. The devices are fabricated using standard semiconductor techniques and off-the-shelf materials, thus enabling integrated diamond photonics.