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Quantum dots are artificial atoms used for a multitude of purposes. Charge defects are commonly present and can significantly perturb the designed energy spectrum and purpose of the dots. Voltage controlled exchange energy in silicon double…

Mesoscale and Nanoscale Physics · Physics 2012-03-21 Rajib Rahman , Erik Nielsen , Richard P. Muller , Malcolm S. Carroll

We present microwave frequency measurements of the dynamic admittance of a quantum dot tunnel coupled to a two-dimensional electron gas. The measurements are made via a high-quality 6.75 GHz on-chip resonator capacitively coupled to the…

Mesoscale and Nanoscale Physics · Physics 2012-10-04 T. Frey , P. J. Leek , M. Beck , J. Faist , A. Wallraff , K. Ensslin , T. Ihn , M. Büttiker

We obtain the finite-temperature unconditional master equation of the density matrix for two coupled quantum dots (CQD) when one dot is subjected to a measurement of its electron occupation number using a point contact (PC). To determine…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 Hsi-Sheng Goan , G. J. Milburn , H. M. Wiseman , He Bi Sun

We propose a nanoscale device consisting of a double quantum dot with strong intra- and inter- dot Coulomb repulsions. In this design, the current can only flow through the lower dot, but is triggered by the gate-controlled occupancy of the…

Mesoscale and Nanoscale Physics · Physics 2021-01-08 Pierre Lombardo , Roland Hayn , Denis Zhuravel , Steffen Schäfer

We derive and evaluate expressions for the low temperature {\it dc} equilibrium tunneling conductance between parallel two-dimensional electron systems. Our theory is based on a linear-response formalism and on impurity-averaged…

Condensed Matter · Physics 2009-10-22 Lian Zheng , A. H. MacDonald

Quantum gates between spin qubits can be implemented leveraging the natural Heisenberg exchange interaction between two electrons in contact with each other. This interaction is controllable by electrically tailoring the overlap between…

We describe the conditional and unconditional dynamics of two coupled quantum dots when one dot is subjected to a measurement of its occupation number using a single electron transistor (SET). The measurement is made when the bare tunneling…

Mesoscale and Nanoscale Physics · Physics 2019-08-17 H. M. Wiseman , Dian Wahyu Utami , He Bi Sun , G. J. Milburn , B. E. Kane , A. Dzurak , R. G. Clark

We experimentally study the transport properties of silicon quantum dots (QDs) fabricated from a highly doped n-type silicon-on-insulator wafer. Low noise electrical measurements using a low temperature complementary…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 T. Kodera , T. Ferrus , T. Nakaoka , G. Podd , M. Tanner , D. Williams , Y. Arakawa

Mathematical correct method for extraction of the complex superconducting energy gap parameter and electron- phonon interaction function from the tunnel density of states is presented. The computer program is shown to be robust against…

Superconductivity · Physics 2007-05-23 A. I. D'yachenko

We report on measurements of single electron tunneling through a quantum dot using a quantum point contact as non-invasive charge detector with fast time response. We elaborate on the unambiguous identification of individual tunneling…

Mesoscale and Nanoscale Physics · Physics 2010-03-03 Christian Fricke , Frank Hohls , Christian Flindt , Rolf J. Haug

We report on the first measurement of the Seebeck coefficient in a tunnel-contacted and gate-tunable individual single-quantum dot junction in the Kondo regime, fabricated using the electromigration technique. This fundamental…

Mesoscale and Nanoscale Physics · Physics 2019-01-31 B. Dutta , D. Majidi , A. Garcia Corral , P. Erdman , S. Florens , T. Costi , H. Courtois , C. B. Winkelmann

We present quantum transport measurements of interacting parallel quantum dots formed in the strands of a carbon nanotube rope. In this molecular quantum dot system, transport is dominated by one quantum dot, while additional resonances…

Mesoscale and Nanoscale Physics · Physics 2015-06-11 Karin Goß , Martin Leijnse , Sebastian Smerat , Maarten R. Wegewijs , Claus M. Schneider , Carola Meyer

A promising path to realizing higher superconducting transition temperatures $T_c$ is the strategic engineering of artificial heterostructures. For example, quantum materials could, in principle, be coupled with other materials to produce a…

Semiconductor qubits rely on the control of charge and spin degrees of freedom of electrons or holes confined in quantum dots (QDs). They constitute a promising approach to quantum information processing [1, 2], complementary to…

A small quantum dot containing approximately 20 electrons is realized in a two-dimensional electron system of an AlGaAs/GaAs heterostructure. Conventional transport and microwave spectroscopy reveal the dot's electronic structure. By…

Mesoscale and Nanoscale Physics · Physics 2019-08-17 H. Qin , F. Simmel , R. H. Blick , J. P. Kotthaus , W. Wegscheider , M. Bichler

The process of tunneling injection is known to improve the dynamical characteristics of quantum well and quantum dot lasers; in the latter, it also improves the temperature performance. The advantage of the tunneling injection process stems…

We measure the interdot charge relaxation time T_1 of a single electron trapped in an accumulation mode Si/SiGe double quantum dot. The energy level structure of the charge qubit is determined using photon assisted tunneling, which reveals…

Mesoscale and Nanoscale Physics · Physics 2014-08-27 K. Wang , C. Payette , Y. Dovzhenko , P. W. Deelman , J. R. Petta

We define single quantum dots of lengths varying from 60 nm up to nearly half a micron in Ge-Si core-shell nanowires. The charging energies scale inversely with the quantum dot length between 18 and 4 meV. Subsequently, we split up a long…

Mesoscale and Nanoscale Physics · Physics 2016-10-13 Matthias Brauns , Joost Ridderbos , Ang Li , Wilfred G. van der Wiel , Erik P. A. M. Bakkers , Floris Zwanenburg

Quantum key distribution (QKD) enables the transmission of information that is secure against general attacks by eavesdroppers. The use of on-demand quantum light sources in QKD protocols is expected to help improve security and maximum…

Ten years ago, coherent oscillations between two quantum states of a superconducting circuit differing by the presence or absence of a single Cooper pair on a metallic island were observed for the first time. This result immediately…

Mesoscale and Nanoscale Physics · Physics 2009-10-19 Vladimir E. Manucharyan , Jens Koch , Markus Brink , Leonid I. Glazman , Michel H. Devoret