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Microwave resonances between discrete macroscopically distinct quantum states with single photon and multiphoton absorption are observed in a strongly driven radio frequency superconducting quantum interference device flux qubit. The…

Quantum Physics · Physics 2015-05-18 Guozhu Sun , Xueda Wen , Yiwen Wang , Shanhua Cong , Jian Chen , Lin Kang , Weiwei Xu , Yang Yu , Siyuan Han , Peiheng Wu

We study optically driven Rabi rotations of a quantum dot exciton transition between 5 and 50 K, and for pulse-areas of up to $14\pi$. In a high driving field regime, the decay of the Rabi rotations is nonmonotonic, and the period decreases…

Mesoscale and Nanoscale Physics · Physics 2010-10-22 A. J. Ramsay , T. M. Godden , S. J. Boyle , E. M. Gauger , A. Nazir , B. W. Lovett , A. M. Fox , M. S. Skolnick

Recent advances in near-field plasmonic metamaterials, such as nanoresonators or transducers, have demonstrated the ability to generate localized fields of high intensity, and thus maintain relatively large nanoscale heat gradients on the…

Mesoscale and Nanoscale Physics · Physics 2022-06-15 Paweł Karwat , Grzegorz Pasławski , Paul Damery , Yanji Yang , Frank Bello , Ortwin Hess

We investigate theoretically the temporal behavior of a quantum dot under off-resonant optical excitation targeted at fast acoustic phonon-assisted state preparation. We demonstrate that in a preparation process driven by short laser pulses…

Mesoscale and Nanoscale Physics · Physics 2016-07-20 A. M. Barth , S. Lüker , A. Vagov , D. E. Reiter , T. Kuhn , V. M. Axt

For a single semiconductor quantum dot embedded in a microcavity, we theoretically and experimentally investigate phonon-assisted transitions between excitons and the cavity mode. Within the framework of the independent boson model we find…

Mesoscale and Nanoscale Physics · Physics 2009-12-21 Ulrich Hohenester , Arne Laucht , Michael Kaniber , Norman Hauke , Abbas Mohtashami , Marek Seliger , Jonathan J. Finley

Excitonic optical transitions in carbon nanotubes (CNTs) have been extensively studied for at least two decades. However, exploiting these transitions to produce a lasing effect has been proved unpractical due to the difficulties of…

Mesoscale and Nanoscale Physics · Physics 2024-10-04 Stefano Dal Forno , Marco Battiato

We investigate exciton spin memory in individual InAs/GaAs self-assembled quantum dots via optical alignment and conversion of exciton polarization in a magnetic field. Quasiresonant phonon-assisted excitation is successfully employed to…

Materials Science · Physics 2009-11-13 K. Kowalik , O. Krebs , A. Lemaître , J. A. Gaj , P. Voisin

The build-up of exciton populations in resonantly laser excited semiconductors is studied microscopically. For excitation at the $2s$-exciton resonance, it is shown that polarization with a strict $s$-type radial symmetry can be efficiently…

Materials Science · Physics 2009-11-10 M. Kira , S. W. Koch

The concept of an acoustical analog of the optical laser has been developed recently both in theoretical as well as experimental works. We discuss here a model of a coherent phonon generator with a direct signature of quantum properties of…

Quantum Physics · Physics 2015-12-24 Victor Ceban , Mihai A. Macovei

Population evolution in a magnetic impurity doped semiconductor quantum dot has been studied by applying a sequence of pulses of chosen pulse area. By optical excitation mechanism, the population in (J_z=+3/2), heavy hole state of valence…

Quantum Physics · Physics 2022-06-01 M K Mehta , P Sen , J T Andrews

We study the phonon-induced dephasing of the exciton state in a quantum dot excited by a sequence of ultra-short pulses. We show that the multiple-pulse control leads to a considerable improvement of the coherence of the optically excited…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 V. M. Axt , P. Machnikowski , T. Kuhn

We demonstrate theoretically that the single-photon purity of photons emitted from a quantum dot exciton prepared by phonon-assisted off-resonant excitation can be significantly higher in a wide range of parameters than that obtained by…

Mesoscale and Nanoscale Physics · Physics 2019-07-08 Michael Cosacchi , Florian Ungar , Moritz Cygorek , Alexei Vagov , Vollrath Martin Axt

We study theoretically the fluctuation properties of acoustic phonons created in a semiconductor quantum dot after ultrafast optical excitation. An excitation with a single ultrafast pulse creates an exciton confined to the quantum dot,…

Mesoscale and Nanoscale Physics · Physics 2015-06-12 D. Wigger , D. E. Reiter , V. M. Axt , T. Kuhn

Quantum emitters promise to emit exactly one photon with high probability when pumped by a laser pulse. However, even in ideal systems, re-excitation during a laser pulse causes the consecutive emission of two photons, thus limiting the…

We demonstrate optical control of the polarization eigenstates of a neutral quantum dot exciton without any external fields. By varying the excitation power of a circularly polarized laser in micro-photoluminescence experiments on…

We propose methods for realization of continuous two photon source using coherently pumped quantum dot embedded inside a photonic crystal cavity. We analyze steady state population in quantum dot energy levels and field inside the cavity…

Quantum Physics · Physics 2020-08-26 Harmanpreet Singh , Manoj Das , P. K. Pathak

In semiconductor quantum dots the coupling to the environment, i.e. to phonons, plays a crucial role for optical state preparation. We analyze the phonon impact on two methods for a direct optical preparation of the dark exciton, which is…

Mesoscale and Nanoscale Physics · Physics 2017-05-17 Sebastian Lüker , Tilmann Kuhn , Doris E. Reiter

We show how population inversion (PI) occurs in a two-level system (TLS) while measuring its charge using a capacitively coupled superconducting single-electron transistor (SSET), biased in the subgap regime, where the current through the…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Goran Johansson

Recently, longitudinal acoustic phonons have been identified as the main source of the intensity damping observed in Rabi rotation measurements of the ground-state exciton of a single InAs/GaAs quantum dot. Here we report experiments of…

Mesoscale and Nanoscale Physics · Physics 2011-06-02 A. J. Ramsay , T. M. Godden , S. J. Boyle , E. M. Gauger , A. Nazir , B. W. Lovett , Achanta Venu Gopal , A. M. Fox , M. S. Skolnick

Bare-state population inversion is demonstrated in a two-level system with all dipole matrix elements nonzero. A laser field is resonantly driving the sample whereas a second weaker and lower frequency coherent field additionally pumps it…

Quantum Physics · Physics 2015-07-31 Mihai Macovei , Mayank Mishra , Christoph H. Keitel