Coupling and Entangling of Quantum States in Quantum Dot Molecules

• Published in: Science (American Association for the Advancement of Science) Vol. 291; no. 5503; pp. 451 - 453
• Main Authors: Bayer, M., Hawrylak, P., Hinzer, K., Fafard, S., Korkusinski, M., Wasilewski, Z. R., Stern, O., Forchel, A.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for the Advancement of Science 19.01.2001; American Association for the Advancement of Science; The American Association for the Advancement of Science
• Subjects: Colloids; Computer engineering; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electric fields; Electron states and collective excitations in thin films, multilayers, quantum wells, mesoscopic and nanoscale systems; Electron tunneling; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electrons; Emission spectra; Engineering; Exact sciences and technology; Excitons; Information Processing; Information storage and retrieval systems; Molecules; Optical data processing; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Particle interactions; Physics; Quantum dots; Quantum electronics; Quantum entanglement; Quantum theory; Quantum tunneling; Energy-level transitions; Excitons; Quantum dots; Hamiltonians; Tunnel effect; Photoluminescence; Theoretical study; Electron hole pair; Spacing; Energy-level splitting
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.291.5503.451

We demonstrate coupling and entangling of quantum states in a pair of vertically aligned, self-assembled quantum dots by studying the emission of an interacting electron-hole pair (exciton) in a single dot molecule as a function of the separation between the dots. An interaction-induced energy splitting of the exciton is observed that exceeds 30 millielectron volts for a dot layer separation of 4 nanometers. The results are interpreted by mapping the tunneling of a particle in a double dot to the problem of a single spin. The electron-hole complex is shown to be equivalent to entangled states of two interacting spins.