Dynamical charge susceptibility in nonequilibrium double quantum dots

Crépieux, Adeline; Lavagna, M.

doi:10.1103/physrevb.106.115439

Cited by 3 publications

(2 citation statements)

References 40 publications

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“…The dynamical charge susceptibility for the systems we consider can be calculated by using the technique of nonequilibrium Green functions. [34] We obtain the following expression…”

Section: Dynamical Charge Susceptibility and Dot Occupancymentioning

confidence: 99%

“…The dynamical charge susceptibility for the systems we consider can be calculated by using the technique of non‐equilibrium Green functions. [ 34 ] We obtain the following expression

\begin{eqnarray} \chi (\omega )=i\int _{-\infty }^\infty \frac{d\varepsilon }{2\pi }\mathrm{Tr}{\left\lbrace \underline{\underline{\bf G}}^&lt;(\varepsilon ){\left[\underline{\underline{\bf G}}^a(\varepsilon -\hbar \omega )+\underline{\underline{\bf G}}^r(\varepsilon +\hbar \omega )\right]}\right\rbrace} \nobreakspace \end{eqnarray}

where

\underline{\underline{\bf G}}^&lt;, \underline{\underline{\bf G}}^r, \underline{\underline{\bf G}}^a

are the lesser, retarded, and advanced Green functions, respectively. The retarded/advanced Green functions

2\times 2

matrices are given by

\begin{matrix} \underset{̲}{\underset{̲}{{boldG}^{r / a}}} false(ε false) = \frac{1}{D^{r / a} false(ε false)} (\begin{matrix} {\tilde{boldg}}_{1}^{r / a} (ε) & {\tilde{boldg}}_{1}^{r / a} (ε) {\tilde{normalΣ}}_{12}^{r / a} (... \end{matrix}) \end{matrix}

…”

Section: Modelmentioning

confidence: 99%

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Finite‐Frequency Noise and Dynamical Charge Susceptibility in Single and Double Quantum Dot Systems

Richard,

Lavagna,

Crépieux

2023

Annalen der Physik

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This study reports on finite‐frequency noise and dynamical charge susceptibility in out‐of‐equilibrium quantum dot systems. Both single and double quantum dots connected to one or two reservoirs of electrons are considered, and these quantities are calculated by using the non‐equilibrium Green function technique. The results are discussed in the light of experimental results, particularly in the low‐frequency limit for which an interpretation in terms of an equivalent RC‐circuit is made. Anti‐symmetrized noise is also studied, defined as the difference between absorption and emission noises, and its relationship with the dynamical charge susceptibility in single quantum dots is established. In double quantum dots, the similarities between the dynamical charge susceptibility, the absorption noise, and the dot occupancy, are highlighted by comparing their respective variations with the bias voltage applied between the two reservoirs, and the detuning energy defined as the difference between the lowest level energies in the two dots.

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“…The dynamical charge susceptibility for the systems we consider can be calculated by using the technique of nonequilibrium Green functions. [34] We obtain the following expression…”

Section: Dynamical Charge Susceptibility and Dot Occupancymentioning

confidence: 99%

“…The dynamical charge susceptibility for the systems we consider can be calculated by using the technique of non‐equilibrium Green functions. [ 34 ] We obtain the following expression

\begin{eqnarray} \chi (\omega )=i\int _{-\infty }^\infty \frac{d\varepsilon }{2\pi }\mathrm{Tr}{\left\lbrace \underline{\underline{\bf G}}^&lt;(\varepsilon ){\left[\underline{\underline{\bf G}}^a(\varepsilon -\hbar \omega )+\underline{\underline{\bf G}}^r(\varepsilon +\hbar \omega )\right]}\right\rbrace} \nobreakspace \end{eqnarray}

where

\underline{\underline{\bf G}}^&lt;, \underline{\underline{\bf G}}^r, \underline{\underline{\bf G}}^a

are the lesser, retarded, and advanced Green functions, respectively. The retarded/advanced Green functions

2\times 2

matrices are given by

\begin{matrix} \underset{̲}{\underset{̲}{{boldG}^{r / a}}} false(ε false) = \frac{1}{D^{r / a} false(ε false)} (\begin{matrix} {\tilde{boldg}}_{1}^{r / a} (ε) & {\tilde{boldg}}_{1}^{r / a} (ε) {\tilde{normalΣ}}_{12}^{r / a} (... \end{matrix}) \end{matrix}

…”

Section: Modelmentioning

confidence: 99%

Finite‐Frequency Noise and Dynamical Charge Susceptibility in Single and Double Quantum Dot Systems

Richard,

Lavagna,

Crépieux

2023

Annalen der Physik

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Entanglement in Quantum Dots: Insights from Dynamic Susceptibility and Quantum Fisher Information

Abouie,

Vashaee

2024

Adv Quantum Tech

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This study investigates the entanglement properties of quantum dots (QDs) under a universal Hamiltonian where the Coulomb interaction between particles (electrons or holes) decouples into charging energy and exchange coupling terms. Although this formalism typically decouples the charge and spin components, confinement‐induced energy splitting can induce unexpected entanglement within the system. By analyzing the dynamic susceptibility and quantum Fisher information (QFI), significant behaviors are uncovered influenced by exchange constants, temperature variations, and confinement effects. In QDs with Ising exchange interactions, far below the Stoner instability (SI) point, where the QD is in a disordered paramagnetic phase, temperature reductions lead to decreased entanglement, challenging conventional expectations. These findings demonstrate that for QDs with small exchange interactions, the responses of easy‐plane () and easy‐axis () configurations are similar, with increased anisotropy broadening susceptibility and shifting its maximum to higher frequencies. For large exchange interactions, the susceptibility differences between easy‐plane and easy‐axis QDs become significant, with easy‐plane QDs exhibiting a higher susceptibility magnitude. Additionally, the study reveals that temperature variations affect the dynamic response functions differently in easy‐axis and easy‐plane QDs. In easy‐plane QDs, QFI consistently decreases with increasing temperature, whereas in easy‐axis QDs, QFI behavior is highly dependent on the strengths of and , showing either an increase or decrease with temperature based on specific coupling conditions. Conversely, at low temperatures, anisotropic Heisenberg models exhibit enhanced entanglement near isotropic points. Overall, this work contributes to advancing the understanding of entanglement in QDs and its potential applications in quantum technologies.

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Beyond-adiabatic Quantum Admittance of a Semiconductor Quantum Dot at High Frequencies: Rethinking Reflectometry as Polaron Dynamics

Peri,

Oakes,

Cochrane

et al. 2024

Quantum

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Semiconductor quantum dots operated dynamically are the basis of many quantum technologies such as quantum sensors and computers. Hence, modelling their electrical properties at microwave frequencies becomes essential to simulate their performance in larger electronic circuits. Here, we develop a self-consistent quantum master equation formalism to obtain the admittance of a quantum dot tunnel-coupled to a charge reservoir under the effect of a coherent photon bath. We find a general expression for the admittance that captures the well-known semiclassical (thermal) limit, along with the transition to lifetime and power broadening regimes due to the increased coupling to the reservoir and amplitude of the photonic drive, respectively. Furthermore, we describe two new photon-mediated regimes: Floquet broadening, determined by the dressing of the QD states, and broadening determined by photon loss in the system. Our results provide a method to simulate the high-frequency behaviour of QDs in a wide range of limits, describe past experiments, and propose novel explorations of QD-photon interactions.

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Dynamical charge susceptibility in nonequilibrium double quantum dots

Cited by 3 publications

References 40 publications

Finite‐Frequency Noise and Dynamical Charge Susceptibility in Single and Double Quantum Dot Systems

Finite‐Frequency Noise and Dynamical Charge Susceptibility in Single and Double Quantum Dot Systems

Entanglement in Quantum Dots: Insights from Dynamic Susceptibility and Quantum Fisher Information

Beyond-adiabatic Quantum Admittance of a Semiconductor Quantum Dot at High Frequencies: Rethinking Reflectometry as Polaron Dynamics

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