1 HIGH-Q OPTICAL NANOCAVITIES IN BULK SINGLE-CRYSTAL DIAMOND Michael J. Burek a , Yiwen Chu b , Madelaine S.Z. Liddy c , Parth Patel c , Jake Rochman c , Srujan Meesala a , Wooyoung Hong a,d , Qimin Quan a,d , Mikhail D. Lukin b , and Marko Lončar a,† a. School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138, USA b. Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138, USA c. University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada d. Rowland Institute at Harvard, Harvard University, 100 Edwin H. Land Blvd., Cambridge, MA 02142, USA † Corresponding author contact: E-mail: loncar@seas.harvard.edu. Tel: (617) 495-579. Fax: (617) 496- 6404.