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We present time-resolved measurements of electron transport through a quantum dot. The measurements were performed using a nearby quantum point contact as a charge detector. The rates for tunneling through the two barriers connecting the…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 S. Gustavsson , R. Leturcq , B. Simovic , R. Schleser , P. Studerus , T. Ihn , K. Ensslin , D. C. Driscoll , A. C. Gossard

We present a new scheme to detect the quantum shot noise in coupled mesoscopic systems. By applying the noise thermometry to the capacitively coupled quantum point contacts (QPCs) we prove that the noise temperature of one QPC is in perfect…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 Masayuki Hashisaka , Yoshiaki Yamauchi , Shuji Nakamura , Shinya Kasai , Teruo Ono , Kensuke Kobayashi

The noise spectra associated with correlations of the current through a single level quantum dot, and with the charge fluctuations on the dot, are calculated for a finite bias voltage. The results turn out to be sensitive to the asymmetry…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 E. A. Rothstein , O. Entin-Wohlman , A. Aharony

Inherent randomness and the resulting stochastic behavior of fundamental particles manifested as quantum noise put a lower bound on measurement imprecision in the quantum measurement process. In addition, the quantum noise imparts…

Mesoscale and Nanoscale Physics · Physics 2025-01-22 Prasanta Kumbhakar , Anusha Shanmugam , Akhileshwar Mishra , Ravi Pant , J L Reno , S Addamane , Madhu Thalakulam

We present finite bias measurements on a quantum dot coupled capacitively to a quantum point contact used as a charge detector. The transconductance signal measured in the quantum point contact at finite dot bias shows structure which…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 R. Schleser , E. Ruh , T. Ihn , K. Ensslin , D. C. Driscoll , A. C. Gossard

We observe individual tunnel events of a single electron between a quantum dot and a reservoir, using a nearby quantum point contact (QPC) as a charge meter. The QPC is capacitively coupled to the dot, and the QPC conductance changes by…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 L. M. K. Vandersypen , J. M. Elzerman , R. N. Schouten , L. H. Willems van Beveren , R. Hanson , L. P. Kouwenhoven

We propose a theoretical model for the low-frequency noise observed in a quantum point contact (QPC) electrostatically defined in the 2D electron gas at a GaAs-AlGaAs interface. In such contacts electron scattering by soft impurity- or…

Condensed Matter · Physics 2009-10-22 J. P. Hessling , Yu. Galperin , M. Jonson , R. I. Shekhter , A. M. Zagoskin

We present a theory for the frequency-dependent current fluctuations in superconducting quantum point-contacts (SQPC) within the dc transport regime. This theory is valid for any barrier transparency between the tunnel and ballistic limits,…

Condensed Matter · Physics 2009-10-28 A. Martin-Rodero , A. Levy Yeyati , F. J. Garcia-Vidal

Detection of the quantum fluctuations by conventional methods meets certain obstacles, since it requires high frequency measurements. Moreover, quantum fluctuations are normally dominated by classical noise, and are usually further…

Mesoscale and Nanoscale Physics · Physics 2012-06-22 Iurii Chernii , Eugene V. Sukhorukov

Quantum dots (QDs) investigated through electron transport measurements often exhibit varying, state-dependent tunnel couplings to the leads. Under specific conditions, weakly coupled states can result in a strong suppression of the…

Mesoscale and Nanoscale Physics · Physics 2018-03-07 M. -C. Harabula , V. Ranjan , R. Haller , G. Fülöp , C. Schönenberger

Cross-correlation heterodyne detectors exhibit the potential for suppression of the detection quantum noise below shot noise without use of optical squeezing for capturing weak optical signals in low frequency bands. To understand the…

Quantum Physics · Physics 2022-11-09 Sheng Feng , Kaikai Wu

We briefly overview our recent results on nonequilibrium interactions between neighboring electrically isolated nanostructures. One of the nanostructures is represented by an externally biased quantum point contact (drive-QPC), which is…

Mesoscale and Nanoscale Physics · Physics 2008-11-25 V. S. Khrapai , S. Ludwig , J. P. Kotthaus , H. P. Tranitz , W. Wegscheider

We study single-electron transport through a double quantum dot (DQD) monitored by a capacitively coupled quantum point-contact (QPC) electrometer. We derive the full counting statistics for the coupled DQD - QPC system and obtain the joint…

Mesoscale and Nanoscale Physics · Physics 2011-08-16 D. S. Golubev , Y. Utsumi , M. Marthaler , Gerd Schoen

The quantum rectification effect observed on asymmetric superconducting loops is proposed to use as a basic of a noise detector with maximum sensitivity. The measurements show that a critical amplitude of noise or ac current decreases down…

Superconductivity · Physics 2007-05-23 V. L. Gurtovoi , S. V. Dubonos , R. V. Kholin , A. V. Nikulov , N. N. Osipov , V. A. Tulin

A quantum dot is a sub-micron-scale conducting device containing up to several thousand electrons. Transport through a quantum dot at low temperatures is a quantum-coherent process. This review focuses on dots in which the electron's…

Mesoscale and Nanoscale Physics · Physics 2008-11-26 Y. Alhassid

The quantum measurement process by a single-electron transistor or a quantum point contact coupled to a quantum bit is studied. We find a unified description of the statistics of the monitored quantity, the current, in the regime of strong…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Yuriy Makhlin , Gerd Schoen , Alexander Shnirman

We investigate an electronic Mach-Zehnder interferometer with high visibility in the quantum Hall regime. The superposition of the electrostatic potentials from a quantum point contact (QPC) and the residual disorder potential from doping…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 L. V. Litvin , A. Helzel , H. -P. Tranitz , W. Wegscheider , C. Strunk

The shot noise in the current through a quantum dot is calculated as a function of voltage from the high-voltage, Coulomb blockaded regime to the low-voltage, Kondo regime. Using several complementary approaches, it is shown that the…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Yigal Meir , Anatoly Golub

We calculate low-frequency noise (LFN) in a quantum point contact (QPC) which is electrostatically defined in a 2D electron gas of a GaAs-AlGaAs heterostructure. The conventional source of LFN in such systems are scattering potentials…

Condensed Matter · Physics 2009-10-22 J. P. Hessling , Yu. Galperin

Based on the scattering matrix theory and non-equilibrium green function method, we have investigated the fluctuations of charge and spin current of the systems which consists of a quantum dot (QD) with a resonant level coupled to two…

Mesoscale and Nanoscale Physics · Physics 2016-08-09 Zahra Sartipi , Javad Vahedi