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We analyze charge tunneling statistics and current noise in a superconducting single-electron transistor in a regime where the Josephson-quasiparticle cycle is the dominant mechanism of transport. Due to the interplay between Coulomb…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 Mahn-Soo Choi , Francesco Plastina , Rosario Fazio

Pre-fault tolerant quantum computers have already demonstrated the ability to estimate observable values accurately, at a scale beyond brute-force classical computation. This has been enabled by error mitigation techniques that often rely…

We consider the problem of continuous quantum measurement of coherent oscillations between two quantum states of an individual two-state system. It is shown that the interplay between the information acquisition and the backaction dephasing…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 A. N. Korotkov , D. V. Averin

Frequency dependent current noise in ferromagnetic double junctions with Coulomb blockade is studied theoretically in the limit of sequential tunneling. Two different relaxation processes are found in the correlations between spin polarized…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 B. R. Bulka , J. Martinek , G. Michalek , J. Barnas

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…

Intrinsic noise is known to be ubiquitous in Josephson junctions. We investigate a voltage biased superconducting tunnel junction including a very small number of pinholes - transport channels possessing a transmission coefficient close to…

Mesoscale and Nanoscale Physics · Physics 2010-05-13 Georg Heinrich , F. K. Wilhelm

We study the current noise through an unbiased quantum electron pump and its mesoscopic fluctuations for arbitrary temperatures and beyond the bilinear response. In the bilinear regime, we find the full distributions of the noise power and…

Mesoscale and Nanoscale Physics · Physics 2009-11-07 M. L. Polianski , M. G. Vavilov , P. W. Brouwer

Parasitic two-level-system (TLS) defects are one of the major factors limiting the coherence times of superconducting qubits. Although there has been significant progress in characterizing basic parameters of TLS defects, exact mechanisms…

We have investigated the effects of quantum fluctuations of quasiparticles on the operation of superconducting radio-frequency single-electron transistors (RF-SETs) for large values of the quasiparticle cotunneling parameter…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Madhu Thalakulam , Z. Ji , A. J. Rimberg

Dissipation of micro- and nano-scale mechanical structures is dominated by quantum-mechanical tunneling of two-level defects intrinsically present in the system. We find that at high frequencies--usually, for smaller, micron-scale…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Kang-Hun Ahn , Pritiraj Mohanty

We study the quantum charge noise and measurement properties of the double Cooper pair resonance point in a superconducting single-electron transistor (SSET) coupled to a Josephson charge qubit. Using a density matrix approach for the…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 A. A. Clerk , S. M. Girvin , A. K. Nguyen , A. D. Stone

Hybrid superconductor/semiconductor devices constitute a powerful platform where intriguing topological properties can be investigated. Here we present fabrication methods and analysis of Josephson junctions formed by a high-mobility InAs…

Mesoscale and Nanoscale Physics · Physics 2019-01-15 Stefano Guiducci , Matteo Carrega , Giorgio Biasiol , Lucia Sorba , Fabio Beltram , Stefan Heun

Synchronization is a widespread phenomenon encountered in many natural and engineered systems with nonlinear classical dynamics. How synchronization concepts and mechanisms transfer to the quantum realm and whether features are universal or…

Mesoscale and Nanoscale Physics · Physics 2024-11-12 Florian Höhe , Lukas Danner , Ciprian Padurariu , Brecht I. C Donvil , Joachim Ankerhold , Björn Kubala

We have used Ramsey tomography to characterize charge noise in a weakly charge-sensitive superconducting qubit. We find a charge noise that scales with frequency as $1/f^\alpha$ over 5 decades with $\alpha = 1.93$ and a magnitude…

An anharmonic oscillator when driven with a fast, frequency chirped voltage pulse can oscillate with either small or large amplitude depending on whether the drive voltage is below or above a critical value-a well studied classical…

Quantum Physics · Physics 2015-05-19 K. W. Murch , R. Vijay , I. Barth , O. Naaman , J. Aumentado , L. Friedland , I. Siddiqi

The main obstacle for practical quantum technology is the noise, which can induce the decoherence and destroy the potential quantum advantages. The fluctuation of a field, which induces the dephasing of the system, is one of the most common…

Quantum Physics · Physics 2020-03-31 Yu Chen , Hongzhen Chen , Jing Liu , Zibo Miao , Haidong Yuan

Qubit noise and fluctuations of the noise over time are key factors limiting the performance of quantum computers. Characterising them with high temporal resolution is challenging due to multiple overlapping stochastic processes such as…

A particular superconducting quantum interference device (SQUID)qubit, indicated as double SQUID qubit, can be manipulated by rapidly modifying its potential with the application of fast flux pulses. In this system we observe coherent…

Superconductivity · Physics 2012-05-08 F. Chiarello , E. Paladino , M. G. Castellano , C. Cosmelli , A. D'Arrigo , G. Torrioli , G. Falci

Charge noise is a major obstacle to improved gate fidelities in silicon spin qubits. Numerous methods exist to mitigate charge noise, including improving device fabrication, dynamical decoupling, and real-time parameter estimation. In this…

Mesoscale and Nanoscale Physics · Physics 2025-05-01 Feiyang Ye , Ammar Ellaboudy , John M. Nichol

We analyze the frequency-dependent noise of a current through a quantum dot which is coupled to Fermi leads and which is in the Coulomb blockade regime. We show that the asymmetric shot noise as function of frequency shows steps and becomes…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Hans-Andreas Engel , Daniel Loss