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A quantum coherent capacitor subject to large amplitude pulse cycles can be made to emit or reabsorb an electron in each half cycle. Quantized currents with pulse cycles in the GHz range have been demonstrated experimentally. We develop a…

Mesoscale and Nanoscale Physics · Physics 2008-02-27 M. Moskalets , P. Samuelsson , M. Buttiker

The evolution of a quantum system is supposed to be impeded by measurement of an involved observable. This effect has been proven indistinguishable from the effect of dephasing the system's wave function, except in an individual quantum…

Quantum Physics · Physics 2009-11-07 Chr. Balzer , R. Huesmann , W. Neuhauser , P. E. Toschek

We study dynamics of the measurement process in quantum dot systems, where a particular state out of coherent superposition is observed. The ballistic point-contact placed near one of the dots is taken as a noninvasive detector. We…

Mesoscale and Nanoscale Physics · Physics 2009-10-30 S. A. Gurvitz

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

A non-equilibrium theory describing the charge qubit dynamics measured by a quantum point contact is developed based on Schwinger-Keldysh's approach. Using the real-time diagram technique, we derive the master equation to all orders in…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 Ming-Tsung Lee , Wei-Min Zhang

We study theoretically transitions of a double quantum-dot qubit caused by nonequilibrium charge fluctuations in a nearby quantum point contact (QPC) used as a detector. We show that these transitions are related to the fundamental…

Mesoscale and Nanoscale Physics · Physics 2010-05-05 C. E. Young , A. A. Clerk

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

Charge detection utilizing a highly biased quantum point contact has become the most effective probe for studying few electron quantum dot circuits. Measurements on double and triple quantum dot circuits is performed to clarify a back…

Mesoscale and Nanoscale Physics · Physics 2008-05-04 D. Taubert , M. Pioro-Ladrière , D. Schröer , D. Harbusch , A. S. Sachrajda , S. Ludwig

The realization of integrated quantum circuits requires precise on-chip control of charge carriers. Aiming at the coherent coupling of distant nanostructures at zero magnetic field, here we study the ballistic electron transport through two…

Mesoscale and Nanoscale Physics · Physics 2020-09-23 Jaan Freudenfeld , Max Geier , Vladimir Umansky , Piet W. Brouwer , Stefan Ludwig

We consider tunneling of spinless electrons from a single-channel emitter into an empty collector through an interacting resonant level of the quantum dot. When all Coulomb screening of sudden charge variations of the dot during the…

Strongly Correlated Electrons · Physics 2017-04-06 V. V. Ponomarenko , I. A. Larkin

We analyze the dynamics of a continuously observed, damped, microwave driven solid state charge qubit. The qubit consists of a single electron in a double well potential, coupled to an oscillating electric field, and which is continuously…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 S. D. Barrett , T. M. Stace

Quantum Zeno dynamics (QZD), which restricts the system's evolution to a protected subspace, provides a promising approach for protecting quantum information from noise. Here, we explore a practical approach to harnessing QZD for robust…

Quantum Physics · Physics 2026-01-06 Ran Liu , Xiaodong Yang , Xiang Lv , Xinyue Long , Hongfeng Liu , Dawei Lu , Ying Dong , Jun Li

The systematical studies on the dynamical approach of wavefunction collapse in quantum measurement are reported in this paper based on the Hepp-Coleman's model and its generalizations. Under certain physically reasonable conditions, which…

High Energy Physics - Theory · Physics 2009-10-28 Chang-Pu Sun

Quantum tunneling is a fundamental quantum mechanical effect involved in plenty of physical phenomena. Its control would impact these phenomena and the technologies based on them. We show that the quantum tunneling probability through a…

Quantum Physics · Physics 2022-08-17 Miguel A. Porras , Nilo Mata , Isabel Gonzalo

It is generally impossible to probe a quantum system without disturbing it. However, it is possible to exploit the back-action of quantum measurements and strong couplings to tailor and protect the coherent evolution of a quantum system.…

We study the influence of a detector on the decay law of a quantum state whose "undisturbed" survival probability is purely exponential. In particular, we consider a detector with a finite energy band of detection, i.e. it interacts only…

Quantum Physics · Physics 2015-06-19 Francesco Giacosa , Giuseppe Pagliara

Quasi-static transport measurements are employed on a laterally defined tunnel-coupled double quantum dot. A nearby quantum point contact allows us to track the charge as added to the device. If charged with only up to one electron, the…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 A. K. Huettel , S. Ludwig , K. Eberl , J. P. Kotthaus

The effect of repetitive measurement for quantum dynamics of driven by an intensive external force of the simple few-level systems as well as of the multilevel systems that exhibit the quantum localisation of classical chaos is…

Quantum Physics · Physics 2008-02-03 B. Kaulakys

We calculate the noise spectrum of the output signal of a quantum detector during continuous measurement of a two-level system (qubit). We generalize the previous results obtained for the regime of high voltages (when $eV$ is much larger…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 A. Shnirman , D. Mozyrsky , I. Martin

We provide a general dynamical approach for the quantum Zeno and anti-Zeno effects in an open quantum system under repeated non-demolition measurements. In our approach the repeated measurements are described by a general dynamical model…

Quantum Physics · Physics 2015-03-19 Peng Zhang , Qing Ai , Yong Li , D. Z. Xu , C. P. Sun