Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:cond-mat/0602199 · Physical Review B

Theory of a double-dot charge detector

Tamás Geszti, József Zsolt Bernád

Published Jun 23, 2006• 9 citations
arXivHTMLPDF

Abstract

A double-quantum-dot charge detector, with one dot Coulomb coupled to the electron to be detected and the other modulated by a time-dependent plunger voltage, is analyzed in a minimal model. The signal and noise of the detector are calculated by a standard master equation and MacDonald formula technique. We find a dip in the noise spectrum at the double Rabi frequency of the double dot, defining the bandwidth available for detecting charges in motion.

DOI
10.1103/physrevb.73.235343

Related papers

Quantum measurement characteristics of a double-dot single electron transistor

HuJun Jiao, Xin-Qi Li, JunYan Luo

Owing to a few unique advantages, the double-dot single electron transistor has been proposed as an alternative detector for charge states. In this work, we present a further study for its signal-to-noise property, based on a full analysis of the setup configuration symmetry. It is found that the effectiveness of the double-dot detector can approach that of an ideal detector, if the symmetric capacitive coupling is taken into account. The quantum measurement efficiency is also analyzed by comparing the measurement time with the measurement-induced dephasing time.

arXiv:cond-mat/0612692•Physical Review B•Apr 26, 2007•19 citations

Time-resolved charge detection with cross-correlation techniques

Bruno Küng, Oliver Pfäffli, Simon Gustavsson +4 more

We present time-resolved charge-sensing measurements on a GaAs double quantum dot with two proximal quantum point-contact (QPC) detectors. The QPC currents are analyzed with cross-correlation techniques, which enable us to measure dot charging and discharging rates for significantly smaller signal-to-noise ratios than required for charge detection with a single QPC. This allows us to reduce the current level in the detector and therefore the invasiveness of the detection process and may help to increase the available measurement bandwidth in noise-limited setups.

arXiv:0810.2406•Physical Review B•Jan 13, 2009•18 citations

Time-dependent single-electron transport through quantum dots

T. Fujisawa, T. Hayashi, Satoshi Sasaki

We describe time-dependent single-electron transport through quantum dots in the Coulomb blockade regime. Coherent dynamics of a single charge qubit in a double quantum dot is discussed with full one-qubit manipulation. Strength of decoherence is controlled with the applied voltage, but uncontrolled decoherence arises from electron–phonon coupling and background fluctuations. Then energy-relaxation dynamics is discussed for orbital and spin degree of freedom in a quantum dot. The electron–phonon interaction and spin–orbit coupling can be investigated as the dissipation problem. Finally, charge detection measurement is presented for statistical analysis of single-electron tunnelling transitions and for a sensitive qubit read-out device.

Reports on Progress in Physics•Feb 20, 2006•111 citations

Application of continuous measurement theory to the current through quantum dots

József Zsolt Bernád, András Bodor, Tamás Geszti +1 more

A simple theory of the detected current $I(t)$ flowing through charge qubits---quantum dots---is proposed in terms of standard continuous measurement theory. Applied to a double dot, our formalism easily confirms previous results on quantum Zeno effect, driven by growing ammeter performance $\ensuremath{\gamma}$. Due to the transparent formalism, we can calculate the exact fluctuation spectrum $S(\ensuremath{\omega})$ of the detected current, containing a significant Lorentzian peak near the Rabi frequency of the double dot.

arXiv:0707.2535•Physical Review B•Feb 25, 2008•5 citations

Noise spectrum of quantum transport through quantum dots: a combined effect of non-Markovian and cotunneling processes

Jinshuang Jin, Wei-Min Zhang, Xin-Qi Li +1 more

Based on our recently developed quantum transport theory in term of an exact master equation, the corresponding particle-number resolved ($n$-resolved) master equation and the related shot noise spectrum formalism covering the full frequency range are constructed. We demonstrate that the noise spectra of transport current through single quantum dot and double quantum dots show characteristic steps and/or peak-dips in different tunneling frequency regimes through tuning the applied bias voltage and/or gate voltage at low temperatures. The peak-dips crossing the tunneling resonant frequencies is a combination effect of non-Markovian and cotunneling processes. These voltage-dependent tunneling resonance characteristics can be utilized to effectively modulate the internal Rabi resonance signature in the noise spectrum.

arXiv:1105.0136•May 1, 2011•1 citation

Non-Markovian decoherence theory for a double-dot charge qubit

Matisse Wei-Yuan Tu, Wei-Min Zhang

In this paper, we develop a nonperturbation theory for describing decoherence dynamics of electron charges in a double quantum dot gated by electrodes. We extend the Feynman-Vernon influence functional theory to fermionic environments and derive an exact master equation for the reduced density matrix of electrons in the double dot for a general spectral density at arbitrary temperature and bias. We then investigate the decoherence dynamics of the double-dot charge qubit with backreaction of the reservoirs being fully taken into account. Time-dependent fluctuations and leakage effects induced from the dot-reservoir coupling are explicitly explored. The charge qubit dynamics from the Markovian to non-Markovian regime is systematically studied under various manipulating conditions. The decay behavior of charge qubit coherence and the corresponding relaxation time ${T}_{1}$ and dephasing time ${T}_{2}$ are analyzed in detail.

arXiv:0809.3490•Physical Review B•Dec 19, 2008•235 citations
A double-quantum-dot charge detector, with one dot Coulomb coupled to the electron to be detected and the other modulated by a time-dependent plunger voltage, is analyzed in a minimal model. The signal and noise of the detector are calculated by a standard master equation and MacDonald formula technique. We find a dip in the noise spectrum at the double Rabi frequency of the double dot, defining the bandwidth available for detecting charges in motion.
Owing to a few unique advantages, the double-dot single electron transistor has been proposed as an alternative detector for charge states. In this work, we present a further study for its signal-to-noise property, based on a full analysis of the setup configuration symmetry. It is found that the effectiveness of the double-dot detector can approach that of an ideal detector, if the symmetric capacitive coupling is taken into account. The quantum measurement efficiency is also analyzed by comparing the measurement time with the measurement-induced dephasing time.
We present time-resolved charge-sensing measurements on a GaAs double quantum dot with two proximal quantum point-contact (QPC) detectors. The QPC currents are analyzed with cross-correlation techniques, which enable us to measure dot charging and discharging rates for significantly smaller signal-to-noise ratios than required for charge detection with a single QPC. This allows us to reduce the current level in the detector and therefore the invasiveness of the detection process and may help to increase the available measurement bandwidth in noise-limited setups.
We describe time-dependent single-electron transport through quantum dots in the Coulomb blockade regime. Coherent dynamics of a single charge qubit in a double quantum dot is discussed with full one-qubit manipulation. Strength of decoherence is controlled with the applied voltage, but uncontrolled decoherence arises from electron–phonon coupling and background fluctuations. Then energy-relaxation dynamics is discussed for orbital and spin degree of freedom in a quantum dot. The electron–phonon interaction and spin–orbit coupling can be investigated as the dissipation problem. Finally, charge detection measurement is presented for statistical analysis of single-electron tunnelling transitions and for a sensitive qubit read-out device.
A simple theory of the detected current I(t)I(t)I(t) flowing through charge qubits---quantum dots---is proposed in terms of standard continuous measurement theory. Applied to a double dot, our formalism easily confirms previous results on quantum Zeno effect, driven by growing ammeter performance $\ensuremath{\gamma}$. Due to the transparent formalism, we can calculate the exact fluctuation spectrum $S(\ensuremath{\omega})$ of the detected current, containing a significant Lorentzian peak near the Rabi frequency of the double dot.
Based on our recently developed quantum transport theory in term of an exact master equation, the corresponding particle-number resolved (nnn-resolved) master equation and the related shot noise spectrum formalism covering the full frequency range are constructed. We demonstrate that the noise spectra of transport current through single quantum dot and double quantum dots show characteristic steps and/or peak-dips in different tunneling frequency regimes through tuning the applied bias voltage and/or gate voltage at low temperatures. The peak-dips crossing the tunneling resonant frequencies is a combination effect of non-Markovian and cotunneling processes. These voltage-dependent tunneling resonance characteristics can be utilized to effectively modulate the internal Rabi resonance signature in the noise spectrum.
In this paper, we develop a nonperturbation theory for describing decoherence dynamics of electron charges in a double quantum dot gated by electrodes. We extend the Feynman-Vernon influence functional theory to fermionic environments and derive an exact master equation for the reduced density matrix of electrons in the double dot for a general spectral density at arbitrary temperature and bias. We then investigate the decoherence dynamics of the double-dot charge qubit with backreaction of the reservoirs being fully taken into account. Time-dependent fluctuations and leakage effects induced from the dot-reservoir coupling are explicitly explored. The charge qubit dynamics from the Markovian to non-Markovian regime is systematically studied under various manipulating conditions. The decay behavior of charge qubit coherence and the corresponding relaxation time T1{T}_{1}T1​ and dephasing time T2{T}_{2}T2​ are analyzed in detail.