1. A. A. Martinos Center for Biomedical Imaging; 149 Thirteenth St., Charlestown, MA 02129 USA
2. Department of Physics; Harvard University; 17 Oxford St, Cambridge, MA 02138 USA
3. ARC Centre of Excellence for Engineered Quantum Systems, School of Physics; The University of Sydney; Sydney, NSW 2006 Australia
4. Harvard Medical School; 25 Shattuck St., Boston, MA 02115 USA
5. Stroke and Neurovascular Regulation Laboratory, Departments of Radiology and Neurology; Massachusetts General Hospital/Harvard Medical School; Charlestown, MA 02129 USA