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We report an electronic magnetization measurement of a quantum point contact (QPC) based on nuclear magnetic resonance (NMR) spectroscopy. We find that NMR signals can be detected by measuring the QPC conductance under in-plane magnetic…

Mesoscale and Nanoscale Physics · Physics 2015-07-16 Minoru Kawamura , Keiji Ono , Peter Stano , Kimitoshi Kono , Tomosuke Aono

In this paper, we study the quantum decoherence induced by accumulation of electron tunnelings during the quantum measurement of a charge qubit. The charge qubit is a single electron confined in coupled quantum dots. The measurement of the…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Ming-Tsung Lee , Wei-Min Zhang

A metallic double-dot is measured with radio frequency reflectometry. Changes in the total electron number of the double-dot are determined via single electron tunnelling contributions to the complex electrical impedance. Electron counting…

Mesoscale and Nanoscale Physics · Physics 2014-04-01 N. J. Lambert , M. Edwards , C. Ciccarelli , A. J. Ferguson

We consider a quantum dot system whose charge fluctuations are monitored by a quantum point contact allowing for the detection of both charge and transferred heat statistics. Our system consists of two nearby conductors that exchange energy…

Mesoscale and Nanoscale Physics · Physics 2013-12-24 Rafael Sánchez , Markus Büttiker

Entanglement between particle and detector is known to be inherent in the measurement process. Gurvitz recently analyzed the coupling of an electron in a double dot (DD) to a quantum point contact (QPC) detector. In this paper we examine…

Quantum Physics · Physics 2009-11-06 Michael Steiner , R. W. Rendell

Electrons trapped on the surface of cryogenic substrates (liquid helium, solid neon or hydrogen) are an emerging platform for quantum information processing made attractive by the inherent purity of the electron environment, the scalability…

The average charge Q on a quantum wire, modeled as a single-channel Luttinger liquid, connected to metallic leads and coupled to a gate is studied theoretically. We find that the behavior of the charge as the gate voltage V_G varies depends…

Strongly Correlated Electrons · Physics 2009-11-10 Jason Alicea , Leon Balents , Cristina Bena , Matthew P. A. Fisher

Nanostructures defined in high-mobility two-dimensional electron systems offer a unique way of controlling the microscopic details of the investigated device. Quantum point contacts play a key role in these investigations, since they are…

Mesoscale and Nanoscale Physics · Physics 2014-03-19 Clemens Rössler , Tobias Krähenmann , Stephan Baer , Thomas Ihn , Klaus Ensslin , Christian Reichl , Werner Wegscheider

The electronic conductance of a molecule making contact to electrodes is determined by the coupling of discrete molecular states to the continuum electrode density of states. Interactions between bound states and continua can be modeled…

Other Condensed Matter · Physics 2007-05-23 Thomas M. Henderson , Giorgos Fagas , Eoin Hyde , James C. Greer

We have studied the single-electron transport spectrum of a quantum dot in GaAs/AlGaAs resonant tunneling device. The measured spectrum has irregularities indicating a broken circular symmetry. We model the system with an external potential…

Strongly Correlated Electrons · Physics 2009-11-10 E. Rasanen , J. Konemann , R. J. Haug , M. J. Puska , R. M. Nieminen

The nonlinear conductance observed in a quantum point contact is theoretically reproduced for the entire range of applied bias. The single-impurity Anderson model with two reservoirs at different chemical potentials is studied for a…

Mesoscale and Nanoscale Physics · Physics 2013-01-25 Jongbae Hong

We show an electron interferometer between a quantum point contact (QPC) and a scanning gate microscope (SGM) tip in a two-dimensional electron gas. The QPC and SGM tip act as reflective barriers of a lossy cavity; the conductance through…

Mesoscale and Nanoscale Physics · Physics 2010-09-21 M. P. Jura , M. A. Topinka , M. Grobis , L. N. Pfeiffer , K. W. West , D. Goldhaber-Gordon

We measure the conductance of a quantum point contact (QPC) while the biased tip of a scanning probe microscope induces a depleted region in the electron gas underneath. At finite magnetic field we find plateaus in the real-space maps of…

Mesoscale and Nanoscale Physics · Physics 2014-03-17 Nikola Pascher , Clemens Rössler , Thomas Ihn , Klaus Ensslin , Christian Reichl , Werner Wegscheider

We demonstrate single-electron pumping in a gate-defined carbon nanotube double quantum dot. By periodic modulation of the potentials of the two quantum dots we move the system around charge triple points and transport exactly one electron…

Mesoscale and Nanoscale Physics · Physics 2012-04-05 S. J. Chorley , J. Frake , C. G. Smith , G. A. C. Jones , M. R. Buitelaar

We study the interaction between two adjacent but electrically isolated quantum point contacts (QPCs). At high enough source-drain bias on one QPC, the drive QPC, we detect a finite electric current in the second, unbiased, detector QPC.…

Mesoscale and Nanoscale Physics · Physics 2007-09-03 V. S. Khrapai , S. Ludwig , J. P. Kotthaus , H. P. Tranitz , W. Wegscheider

Single molecules that exhibit narrow optical transitions at cryogenic temperatures can be used as local electric-field sensors. We derive the single charge sensitivity of aromatic organic dye molecules, based on first principles. Through…

Mesoscale and Nanoscale Physics · Physics 2015-06-23 Sanli Faez , Sense Jan van der Molen , Michel Orrit

We perform a fully quantum mechanical numerical calculation for the problem of a single electron (or excitation) propagating in a N-site one-dimensional chain in the presence of a single Holstein impurity. We compute the long-time averaged…

Disordered Systems and Neural Networks · Physics 2009-10-30 M. I. Molina , J. A Roessler , G. P. Tsironis

There has been considerable progress in electro-statically emptying, and re-filling, quantum dots with individual electrons. Typically the quantum dot is defined by electrostatic gates on a GaAs/AlGaAs modulation doped heterostructure. We…

We present a scheme for tuning two quantum point contacts as a quantum-limited charge detector. Based on the scattering matrix approach, we analyze a general condition of quantum-limited detection with a single-channel quantum detector…

Mesoscale and Nanoscale Physics · Physics 2012-08-06 Kang-Ho Lee , Kicheon Kang

We study a voltage-driven quantum point contact (QPC) strongly coupled to a qubit. We predict pronounced observable features in the QPC current that can be interpreted in terms of half-integer charge transfers. Our analysis is based on the…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 I. Snyman , Y. V. Nazarov