[1] Univ Colorado, Dept Phys, Boulder, CO 80309 USA
[2] Univ Colorado, Ctr Theory Quantum Matter, Boulder, CO 80309 USA
[3] CALTECH, Dept Phys, Pasadena, CA 91125 USA
[4] Natl Univ Singapore, Dept Phys, Singapore 117551, Singapore
[5] Natl Univ Singapore, Ctr Quantum Technol, Singapore 117543, Singapore
[6] SUNY Stony Brook, Inst Theoret Phys, Stony Brook, NY 11794 USA
[7] SUNY Stony Brook, Dept Phys & Astron, Stony Brook, NY 11794 USA
[8] Leibniz Univ Hannover, Inst Theoret Phys, D-30167 Hannover, Germany
[9] Univ British Columbia, Stewart Blusson Quantum Matter Inst, Vancouver, BC V6T 1Z4, Canada
[10] Harvard Univ, Dept Phys, Cambridge, MA 02138 USA