title: Dynamic hole blockade yields two-color quantum and classical light from dot-in-bulk nanocrystals.
abstract: Semiconductor nanocrystals (NCs) are an emerging class of color-tunable, solution-processable, room-temperature single-photon sources. Photon antibunching in NCs arises from suppression of multiphoton emission by nonradiative Auger recombination. Here, we demonstrate a new antibunching mechanism-dynamic Coulomb blockade-which allows for generating both quantum and classical light from the same NC without detrimental effects of Auger decay. This mechanism is realized in novel dot-in-bulk (DiB) nanostructures comprising a quantum-confined CdSe core overcoated with a thick, bulk-like CdS shell. The presence of one hole in the core suppresses the capture of the second hole forcing it to recombine in the shell region. Under weak excitation, these NCs emit red antibunched light (core emission). At higher pump levels they exhibit an additional green band (shell emission) with bulk-like, Poissonian photon statistics. The unusual versatility of these novel nanoscale light sources, that combine mutually correlated channels for quantum and classical emission and additionally allow for facile tunability of effective color, opens new interesting opportunities for a range of applications from quantum optics to sensing and nanoscale imaging.
authors.affiliation: Chemistry Division and Center for Advanced Solar Photophysics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Christophe
authors.initials: C
authors.lastname: Galland
authors.forename: Sergio
authors.initials: S
authors.lastname: Brovelli
authors.forename: Wan Ki
authors.initials: WK
authors.lastname: Bae
authors.forename: Lazaro A
authors.initials: LA
authors.lastname: Padilha
authors.forename: Francesco
authors.initials: F
authors.lastname: Meinardi
authors.forename: Victor I
authors.initials: VI
authors.lastname: Klimov