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We observe the low-lying excitations of a molecular dimer formed by two electrons in a GaAs semiconductor quantum dot in which the number of confined electrons is tuned by optical illumination. By employing inelastic light scattering we…

Mesoscale and Nanoscale Physics · Physics 2010-06-16 Achintya Singha , Vittorio Pellegrini , Aron Pinczuk , Loren N. Pfeiffer , Ken W. West , Massimo Rontani

Hereby, we study the generation of pairs of polarization-entangled photons at telecom C-band by biexciton-exciton cascade from non-resonantly excited epitaxial InAs/InP quantum dots (QDs). It is realized without external tuning of the fine…

A sequence of photoluminescence spectroscopy based methods are used to rigorously identify and study all the main spectral features (more than thirty emission lines) of site controlled InGaAs/AlGaAs quantum dots (QDs) grown along [111]B in…

A concept for the fabrication of highly symmetric quantum dots that are coherently embedded in a single crystalline matrix is demonstrated. In this approach, the formation of the quantum dots is induced by a transformation of an epitaxial…

Materials Science · Physics 2009-11-11 W. Heiss , H. Groiss , E. Kaufmann , G. Hesser , M. Boberl , G. Springholz , F. Schaffler , K. Koike , H. Harada , M. Yano

Coupled colloidal quantum dot molecules composed of two fused CdSe/CdS core/shell sphere monomers were recently presented. Upon fusion, the potential energy landscape is changing into two quantum dots separated by a pre-tuned potential…

Mesoscale and Nanoscale Physics · Physics 2019-12-11 Yossef E. Panfil , Doaa Shamalia , Jiabin Cui , Somnath Koley , Uri Banin

Quantum dots acting as single photon emitters in the blue-green range are fabricated and characterized at cryogenic temperature. They consist in CdSe dots inserted in (Zn,Mg)Se nanowires with a thick shell. Photoluminescence spectra, decay…

We study the exciton spin relaxation in CdTe self-assembled quantum dots by using polarized photoluminescence spectroscopy in magnetic field. The experiments on single CdTe quantum dots and on large quantum dot ensembles show that by…

We present a comprehensive photoluminescence study of exchange interaction in self-assembled CdTe/ZnTe quantum dots. We exploit the presence of multiple charge states in the photoluminescence spectra of single quantum dots to analyze…

We systematically study the coupling of longitudinal modes (shells) in a carbon nanotube quantum dot. Inelastic cotunneling spectroscopy is used to probe the excitation spectrum in parallel, perpendicular and rotating magnetic fields. The…

Mesoscale and Nanoscale Physics · Physics 2019-01-23 M. C. Hels , T. S. Jespersen , J. Nygård , K. Grove-Rasmussen

Tunneling excitations of electrons in dry-etched modulation-doped AlGaAs/GaAs coupled quantum dots (QDs) are probed by resonant inelastic light scattering. A sequence of intra- and intershell excitations are found at energies determined by…

We study the electronic structure of a single self-assembled InAs quantum dot by probing elastic single-electron tunneling through a single pair of weakly coupled dots. In the region below pinch-off voltage, the non-linear threshold voltage…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 T. Ota , K. Ono , M. Stopa , T. Hatano , S. Tarucha , H. Z. Song , Y. Nakata , T. Miyazawa , T. Ohshima , N. Yokoyama

We studied a vertical ``quantum dot molecule'', where one of the dots is occupied with electrons and the other with holes. We find that different phases occur in the ground state, depending on the carrier density and the interdot distance.…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 K. Karkkainen , M. Koskinen , M. Manninen , S. M. Reimann

We present photoluminescence studies of CdTe and CdMnTe quantum dots grown in two adjacent layers. We show that when the dots are 8 nm apart, their magnetooptical properties - Zeeman shifts and transition linewidths - are analogous to those…

Mesoscale and Nanoscale Physics · Physics 2015-08-12 Ł. Kłopotowski , P. Wojnar , Ł. Cywiński , T. Jakubczyk , M. Goryca , K. Fronc , T. Wojtowicz , G. Karczewski

Excitonic spectra are calculated for free-standing, surface passivated InAs quantum dots using atomic pseudopotentials for the single-particle states and screened Coulomb interactions for the two-body terms. We present an analysis of the…

Materials Science · Physics 2009-10-31 A. J. Williamson , Alex Zunger

We present the photoluminescence excitation study of the self-assembled CdTe/ZnTe quantum dots doped with manganese ions. We demonstrate the identification method of spontaneously coupled quantum dots pairs containing single Mn2+ ions. As…

Mesoscale and Nanoscale Physics · Physics 2015-06-17 M. Koperski , M. Goryca , T. Kazimierczuk , T. Smoleński , A. Golnik , P. Wojnar , P. Kossacki

We theoretically study the excitation spectrum of confined macroscopic optical lattices in the Mott-insulating limit. For large systems, a fast numerical method is proposed to calculate the ground state filling and excitation energies. We…

Quantum Gases · Physics 2009-06-30 Dirk-Sören Lühmann , Kai Bongs , Daniela Pfannkuche

In spite of a large quantity of papers devoted to the mangetoluminescence from CdTe/(Cd,Mg)Te, quantum wells there have been no attempts to analyze it on the basis of the band-structure calculations. This has been proposed in the present…

We report on photon coincidence measurement in a single GaAs self-assembled quantum dot (QD) using a pulsed excitation light source. At low excitation, when a neutral exciton line was present in the photoluminescence (PL) spectrum, we…

We demonstrate an efficient method to engineer the quantum confinement in a system of two quantum dots grown in a vertical stack. We achieve this by using materials with a different lattice constant for the growth of the outer and inner…

Mesoscale and Nanoscale Physics · Physics 2015-02-13 Ł. Kłopotowski , P. Wojnar , S. Kret , M. Parlińska-Wojtan , K. Fronc , G. Karczewski , T. Wojtowicz

This work presents epitaxial growth and optical spectroscopy of CdTe quantum dots (QDs) in (Cd,Zn,Mg)Te barriers placed on the top of (Cd,Zn,Mg)Te distributed Bragg reflector. The formed photonic mode in our half-cavity structure permits to…

Mesoscale and Nanoscale Physics · Physics 2017-03-24 W. Pacuski , J. -G. Rousset , V. Delmonte , T. Jakubczyk , K. Sobczak , J. Borysiuk , K. Sawicki , E. Janik , J. Kasprzak