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Exchange-coupled singlet-triplet spin qubits in two gate-defined double quantum dots are considered theoretically. Using charge density operators to describe the double-dot orbital states, we calculate the Coulomb couplings between the…

Mesoscale and Nanoscale Physics · Physics 2015-05-28 Guy Ramon

We report measurements of dynamical tunneling rates of a Bose-Einstein condensate across a barrier in classical phase space. The atoms are initially prepared in quantum states that extend over a classically regular island region. We focus…

Quantum Physics · Physics 2013-09-16 R. K. Shrestha , J. Ni , W. K. Lam , G. S. Summy , S. Wimberger

We consider the form of the current-voltage curves generated when tunneling spectroscopy is used to measure the energies of individual electronic energy levels in nanometer-scale systems. We point out that the voltage positions of the…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Edgar Bonet , Mandar M. Deshmukh , D. C. Ralph

We study two-electron states confined in two coupled quantum dots formed by a short-range potential in a two-dimensional topological insulator. It is shown that there is a fairly wide range of the system parameters, where the ground state…

Mesoscale and Nanoscale Physics · Physics 2018-09-17 Vladimir A. Sablikov , Aleksei A. Sukhanov

We theoretically investigate the Stark shift of the exciton goundstate in two vertically coupled quantum dots as a function of the interdot distance. The coupling is shown to enhance the tuneability of the linear optical properties,…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 F. Troiani , E. Molinari

We report the realization of a quadruple quantum dot device in a square-like configuration where a single electron can be transferred on a closed path free of other electrons. By studying the stability diagrams of this system, we…

Mesoscale and Nanoscale Physics · Physics 2012-09-05 Romain Thalineau , Sylain Hermelin , Andreas D. Wieck , Christopher Bäuerle , Laurent Saminadayar , Tristan Meunier

Single electron tunneling is studied in a many electron quantum dot in high magnetic fields. For such a system multiple transitions of the spin configuration are theoretically predicted. With a combination of spin blockade and Kondo effect…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 M. C. Rogge , C. Fuhner , R. J. Haug

We study electron transfer between two separated nuclei using local control theory. By conditioning the algorithm in a symmetric system formed by two protons, one can favored slow transfer processes, where tunneling is the main mechanism,…

Quantum Physics · Physics 2018-04-18 Patricia Vindel-Zandbergen , Christoph Meier , Ignacio R. Sola

We prepare a gate-defined quadruple quantum dot to study the gate-tunability of single to quadruple quantum dots with finite inter-dot tunnel couplings. The measured charging energies of various double dots suggest that the dot size is…

Mesoscale and Nanoscale Physics · Physics 2014-03-21 Tatsuki Takakura , Akito Noiri , Toshiaki Obata , Tomohiro Otsuka , Jun Yoneda , Katsuharu Yoshida , Seigo Tarucha

We present real-time detection measurements of electron tunneling in a graphene quantum dot. By counting single electron charging events on the dot, the tunneling process in a graphene constriction and the role of localized states are…

Mesoscale and Nanoscale Physics · Physics 2011-05-03 J. Guettinger , J. Seif , C. Stampfer , A. Capelli , K. Ensslin , T. Ihn

We explore the full counting statistics of single electron tunneling through a quantum dot using a quantum point contact as non-invasive high bandwidth charge detector. The distribution of counted tunneling events is measured as a function…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 C. Fricke , F. Hohls , W. Wegscheider , R. J. Haug

We use time-resolved charge detection techniques to investigate single-electron tunneling in semiconductor quantum dots. The ability to detect individual charges in real-time makes it possible to count electrons one-by-one as they pass…

Mesoscale and Nanoscale Physics · Physics 2009-05-29 S. Gustavsson , R. Leturcq , M. Studer , I. Shorubalko , T. Ihn , K. Ensslin , D. C. Driscoll , A. C. Gossard

We use time-resolved charge detection techniques to probe virtual tunneling processes in a double quantum dot. The process involves an energetically forbidden state separated by an energy $\delta$ from the Fermi energy in the leads. The…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 S. Gustavsson , M. Studer , R. Leturcq , T. Ihn , K. Ensslin , D. C. Driscoll , A. C. Gossard

We investigate the effect of a quantised vibrational mode on electron tunneling through a chain of three quantum dots. The outer dots are coupled to voltage leads, but the position of the central dot is not rigidly fixed. Motion of the…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 A. D. Armour , A. MacKinnon

We demonstrate a new method for locally probing the edge states in the quantum Hall regime utilizing a side coupled quantum dot positioned at an edge of a Hall bar. By measuring the tunneling of electrons from the edge states into the dot,…

Mesoscale and Nanoscale Physics · Physics 2011-06-14 Tomohiro Otsuka , Eisuke Abe , Yasuhiro Iye , Shingo Katsumoto

A pulsed-gate technique with charge sensing is used to measure the singlet-triplet relaxation time for nearly-degenerate spin states in a two-electron double quantum dot. Transitions from the (1,1) charge occupancy state to the (0,2) state,…

Mesoscale and Nanoscale Physics · Physics 2013-07-24 J. R. Petta , A. C. Johnson , A. Yacoby , C. M. Marcus , M. P. Hanson , A. C. Gossard

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

By measuring electron tunneling between a ferromagnet and individual energy levels in an aluminum quantum dot, we show how spin-resolved quantum states can be used as filters to determine spin-dependent tunneling rates. We also observe…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Mandar M. Deshmukh , D. C. Ralph

We predict wide-band suppression of tunneling of spin-orbit-coupled atoms (or noninteracting Bose-Einstein condensate) in a double-well potential with periodically varying depths of the potential wells. The suppression of tunneling is…

Quantum Physics · Physics 2018-06-19 Y. V. Kartashov , V. V. Konotop , V. A. Vysloukh

We report integrated charge sensing measurements on a Si/SiGe double quantum dot. The quantum dot is shown to be tunable from a single, large dot to a well-isolated double dot. Charge sensing measurements enable the extraction of the tunnel…