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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

A theory is developed for the emission noise at frequency $\nu$ in a quantum dot in the presence of Coulomb interactions and asymmetric couplings to the reservoirs. We give an analytical expression for the noise in terms of the various…

Mesoscale and Nanoscale Physics · Physics 2018-03-15 A. Crépieux , S. Sahoo , T. Q. Duong , R. Zamoum , M. Lavagna

We investigate nonequilibrium transport in a triple-quantum-dot (TQD) system, where the central dot acts as a discrete tunnel barrier, subject to continuous monitoring by a quantum point contact (QPC) that is capacitively coupled to all…

Mesoscale and Nanoscale Physics · Physics 2026-05-20 Alok Nath Singh , Rafael Sánchez , Andrew N. Jordan

The theory of quantum chromodynamics (QCD) encodes the strong interactions that bind quarks and gluons into nucleons and that bind nucleons into nuclei. Predictive control of QCD would allow nuclear structure and reactions as well as…

High Energy Physics - Lattice · Physics 2017-11-02 Michael L. Wagman

In this work we analyze how coherent transport through a Quantum Dot (QD) in the Kondo regime is affected by the weak capacitive interaction with a nearby biased Quantum Point Contact (QPC). We find that when the QD-QPC interaction is weak…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Alessandro Silva , Shimon Levit

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

In the ideal quantum Zeno effect, repeated quantum projective measurements can freeze the coherent dynamics of a quantum system. However, in the weak quantum Zeno regime, measurement back-actions can allow the sensing of semi-classical…

We investigate the effect of quantum noise on the measurement-induced quantum phase transition in monitored random quantum circuits. Using the efficient simulability of random Clifford circuits, we find that the transition is broadened into…

Quantum Physics · Physics 2022-08-31 Beatriz C. Dias , Domagoj Perkovic , Masudul Haque , Pedro Ribeiro , Paul A. McClarty

Characterizing noise in superconducting qubits is essential for improving coherence and gate performance. Conventional noise-sensing methods typically use the qubit itself as the sensor, which limits both accessible bandwidth and…

Quantum Physics · Physics 2026-04-10 Nitzan Kahn , Dror Garti , Uri Goldblatt , Lalit M. Joshi , Fabien Lafont , Serge Rosenblum

We study the real-time emission of single electrons from a quantum dot coupled to a one dimensional conductor, using exact diagonalization on a discrete tight-binding chain. We show that from the calculation of the time-evolution of the one…

Mesoscale and Nanoscale Physics · Physics 2012-01-27 T. Jonckheere , T. Stoll , J. Rech , T. Martin

We performed measurements on a quantum dot and a capacitively coupled quantum point contact by using the sharp metallic tip of a low-temperature scanning force microscope as a scanned gate. The quantum point contact served as a detector for…

Mesoscale and Nanoscale Physics · Physics 2011-11-09 A. E. Gildemeister , T. Ihn , R. Schleser , K. Ensslin , D. C. Driscoll , A. C. Gossard

Critical current fluctuations with a 1/ f spectral density (f is frequency) are potentially a limiting source of intrinsic decoherence in superconducting quantum bits (qubits) based on Josephson tunnel junctions. Prior measurements of this…

Superconductivity · Physics 2007-05-23 Michael Mueck , Matthias Korn , C. G. A. Mugford , J. B. Kycia , John Clarke

We demonstrate a novel method for measuring the discrete energy spectrum of a quantum dot connected very weakly to a single lead. A train of voltage pulses applied to a metal gate induces tunneling of electrons between the quantum dot and a…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 J. M. Elzerman , R. Hanson , L. H. Willems van Beveren , L. M. K. Vandersypen , L. P. Kouwenhoven

We have developed an etching process to fabricate a quantum dot and a nearby single electron transistor as a charge detector in a single layer graphene. The high charge sensitivity of the detector is used to probe Coulomb diamonds as well…

Mesoscale and Nanoscale Physics · Physics 2015-05-19 Ling-Jun Wang , Gang Cao , Tao Tu , Hai-Ou Li , Cheng Zhou , Xiao-Jie Hao , Zhan Su , Guang-Can Guo , Guo-Ping Guo , Hong-Wen Jiang

We report the realization of a bonded-bridge on-chip superconducting coil and its use in impedance-matching a highly ohmic quantum dot (QD) to a $\rm{3~GHz}$ measurement setup. The coil, modeled as a lumped-element $LC$ resonator, is more…

Quantum Physics · Physics 2018-01-03 M. -C. Harabula , T. Hasler , G. Fülöp , M. Jung , V. Ranjan , C. Schönenberger

In analogy with quantum optics, short time correlations of the current fluctuations are used to characterize an on-demand electron source consisting of a quantum dot connected to a conductor via a tunable tunnel barrier. We observe a new…

Mesoscale and Nanoscale Physics · Physics 2015-05-18 A. Mahé , F. D. Parmentier , E. Bocquillon , J. -M. Berroir , D. C. Glattli , T. Kontos , B. Plaçais , G. Fève , A. Cavanna , Y. Jin

We consider the dephasing rate of an electron level in a quantum dot, placed next to a fluctuating edge current in the fractional quantum Hall effect. Using perturbation theory, we show that this rate has an anomalous dependence on the bias…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Thi Kim Thanh Nguyen , Adeline Crepieux , Thibaut Jonckheere , Ai Viet Nguyen , Yeoshua Levinson , Thierry Martin

We show how the charge input signal applied to the gate electrode in a double and triple quantum dot may be converted to a pulse in the Kondo cotunneling current being a spin response of a nano-device under a strong Coulomb blockade. The…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 M. N. Kiselev , K. Kikoin , J. Richert

The dynamic capture of electrons in a semiconductor quantum dot (QD) by raising a potential barrier is a crucial stage in metrological quantized charge pumping. In this work, we use a quantum point contact (QPC) charge sensor to study…

Mesoscale and Nanoscale Physics · Physics 2018-09-27 S. P. Giblin , P. See , A. Petrie , T. J. B. M. Janssen , I. Farrer , J. P. Griffiths , G. A. C. Jones , D. A. Ritchie , M. Kataoka

We study two quantum dots in the limit of strong dot-lead coupling and weak dot-dot tunneling. The model maps on Ising-coupled Kondo impurities. We argue that a new quantum critical fixed point exists at an intermediate value of the mutual…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Natan Andrei , Gergely T. Zimanyi , Gerd Schoen