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Current fluctuations can provide additional insight into quantum transport in mesoscopic systems. The present work is carried out for the fluctuation properties of transport through a pair of coupled quantum dots which are connected with…

Mesoscale and Nanoscale Physics · Physics 2009-09-02 JunYan Luo , Xin-Qi Li , YiJing Yan

We consider dissipative dynamics of a flux qubit caused by 1/f noises, which act both on the shunting LC-contour and on the SQUID loop. These classical Gaussian noises modulate of the level splitting and of the tunnel coupling,…

Mesoscale and Nanoscale Physics · Physics 2018-07-25 F. T. Vasko

The efficiency of the future devices for quantum information processing will be limited mostly by the finite decoherence rates of the individual qubits and quantum gates. Recently, substantial progress was achieved in enhancing the time…

Mesoscale and Nanoscale Physics · Physics 2014-04-10 E. Paladino , Y. M. Galperin , G. Falci , B. L. Altshuler

We develop a theory of spin fluctuations of exciton-polaritons in a semiconductor microcavity under the non-resonant unpolarized pumping. It is shown that the corresponding spin noise is sensitive to the scattering rates in the system,…

Mesoscale and Nanoscale Physics · Physics 2015-06-15 M. M. Glazov , M. A. Semina , E. Ya. Sherman , A. V. Kavokin

Using spin-echo Nuclear Magnetic Resonance in the model Transverse-Field Ising system TmVO$_4$, we show that low frequency quantum fluctuations at the quantum critical point have a very different effect on $^{51}$V nuclear-spins than…

Strongly Correlated Electrons · Physics 2024-05-24 Y-H. Nian , I. Vinograd , T. Green , C. Chaffey , P. Massat , R. R. P. Singh , M. P. Zic , I. R. Fisher , N. J. Curro

Charge noise in the host semiconductor degrades the performance of spin-qubits and poses an obstacle to control large quantum processors. However, it is challenging to engineer the heterogeneous material stack of gate-defined quantum dots…

Superconducting Quantum Interference Devices (SQUIDs) and other superconducting circuits are limited by intrinsic flux noise with spectral density $1/f^{\alpha}$ with $\alpha<1$ whose origin is believed to be due to spin impurities. Here we…

Superconductivity · Physics 2022-07-22 S. LaForest , Rogerio de Sousa

Not all noise in experimental measurements is unwelcome. Certain fundamental noise sources contain valuable information about the system itself -- a notable example being the inherent voltage fluctuations that exist across any resistor…

Disordered Systems and Neural Networks · Physics 2009-11-10 S. A. Crooker , D. G. Rickel , A. V. Balatsky , D. L. Smith

Low frequency noise close to the carrier remains little explored in spin torque nano oscillators. However, it is crucial to investigate as it limits the oscillator's frequency stability. This work addresses the low offset frequency flicker…

Macroscopic resonant tunneling between the two lowest lying states of a bistable RF-SQUID is used to characterize noise in a flux qubit. Measurements of the incoherent decay rate as a function of flux bias revealed a Gaussian shaped profile…

Unwanted fluctuations over time, in short, noise, are detrimental to device performance, especially for quantum coherent circuits. Recent efforts have demonstrated routes to utilizing magnon systems for quantum technologies, which are based…

Mesoscale and Nanoscale Physics · Physics 2021-12-08 Tim Wolz , Luke McLellan , Alexander Stehli , Andre Schneider , Jan David Brehm , Hannes Rotzinger , Alexey V. Ustinov , Martin Weides

The coherence of electron spin qubits in semiconductor quantum dots suffers mostly from low-frequency noise. During the last decade, efforts have been devoted to mitigate such noise by material engineering, leading to substantial…

We present a scenario for the peculiar coexistence of charge fluctuations observed in quasi-2D 1/4-filled organic conductors $\theta$-(BEDT-TTF)$_2X$ in the quantum critical regime where the charge ordering is suppressed down to zero…

Strongly Correlated Electrons · Physics 2009-11-13 Masafumi Udagawa , Yukitoshi Motome

We present a new method to measure 1/f noise in Josephson quantum bits (qubits) that yields low-frequency spectra below 1Hz. Comparison of noise taken at positive and negative bias of a phase qubit shows the dominant noise source to be flux…

Recent experiments by F. Yoshihara et al. [Phys. Rev. Lett. 97, 167001 (2006)] and by K. Kakuyanagi et al. (cond-mat/0609564) provided information on decoherence of the echo signal in Josephson-junction flux qubits at various bias…

Superconductivity · Physics 2009-11-11 Y. M. Galperin , B. L. Altshuler , J. Bergli , D. Shantsev , V. Vinokur

Slow fluctuations of a qubit frequency are one of the major problems faced by quantum computers. To understand their origin it is necessary to go beyond the analysis of their spectra. We show that characteristic features of the fluctuations…

Quantum Physics · Physics 2024-01-11 Filip Wudarski , Yaxing Zhang , M. I. Dykman

The analysis of charge noise based on the Bloch-Redfield treatment of an ensemble of dissipative two-level fluctuators generally results in a violation of the fluctuation-dissipation theorem. The standard Markov approximation (when applied…

Quantum Physics · Physics 2021-01-19 Xinyuan You , Aashish A. Clerk , Jens Koch

Quantum sensors and qubits are usually two-level systems (TLS), the quantum analogs of classical bits which assume binary values '0' or '1'. They are useful to the extent to which they can persist in quantum superpositions of '0' and '1' in…

Quantum Physics · Physics 2024-01-19 A. Beckert , M. Grimm , N. Wili , R. Tschaggelar , G. Jeschke , G. Matmon , S. Gerber , M. Müller , G. Aeppli

Theoretical and experimental work concerned with dynamic fluctuations has developed into a very active and fascinating subfield of mesoscopic physics. We present a review of this development focusing on shot noise in small electric…

Mesoscale and Nanoscale Physics · Physics 2016-08-31 Ya. M. Blanter , M. Buttiker

We study the dynamics of a pulse-gated semiconductor double quantum dot qubit. In our experiments, the qubit coherence times are relatively long, but the visibility of the quantum oscillations is low. We show that these observations are…