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

Communications in Theoretical Physics

Decoherence of a Double Quantum Dot Charge Qubit Approached with Redfield Equation

Zeng-Zhao Li, Zhiqiang Li

Published Feb 1, 2009• 0 citations
Publisher

Abstract

In this paper, we investigate the decoherence time of a double quantum dot (DQD) charge qubit in three kinds of baths through solving dynamics of the qubit. The dynamics of the qubit is investigated with Redfield master equation. It is shown that the decoherence time of the qubit in Ohmic bath has the same order of magnitude as the experiments reported. When the environment is modeled with the supra-Ohmic bath the decoherence time of the qubit is shorter than the experimental result. And when modeled with the sub-Ohmic bath the decoherence time of the qubit is longer than the experimental result.

DOI
10.1088/0253-6102/51/2/31

Related papers

Non-Markovian dynamics and phonon decoherence of a double quantum dot charge qubit

Xian-Ting Liang

In this paper we investigate decoherence times of a double quantum dot (DQD) charge qubit due to it coupling with acoustic phonon baths. We individually consider the acoustic piezoelectric as well as deformation coupling phonon baths in the qubit environment. The decoherence times are calculated with two kinds of methods. One of them is based on the qusiadiabatic propagator path integral (QUAPI) and the other is based on Bloch equations, and two kinds of results are compared. It is shown that the theoretical decoherence times of the DQD charge qubit are shorter than the experimental reported results. It implies that the phonon couplings to the qubit play a subordinate role, resulting in the decoherence of the qubit.

arXiv:quant-ph/0506258•Physical Review B•Dec 21, 2005•26 citations

Decoherence of a Double Quantum Dot Charge Qubit Approached with Redfield Equation

LI ., Zeng-Zhao, Zhiqiang

在这篇论文，我们调查一个双量点(DQD ) 的 decoherence 时间在通过解决 qubit 的动力学的三种洗澡的费用 qubit。qubit 的动力学与 Redfield 主人方程被调查。在欧姆的洗澡的 qubit 的 decoherence 时间把象实验的一样的数量级报导，这被显示出。当环境与在上被建模时 -- 欧姆的洗澡 qubit 的 decoherence 时间比试验性的结果短。并且当与亚 Ohmic 洗澡当模特儿时， qubit 的 decoherence 时间比试验性的结果长。

理论物理通讯：英文版•Jan 1, 2009•0 citations

Short-Time Effects of Environment to Josephson Charge Qubit: A Master Equation Approach

Zhiqiang Li, Xian-Ting Liang

In this paper we investigate an environmental effects to Josephson charge qubit (JCQ) when the environment is taken as the Ohmic bath. At first, we derive the master equation from a JCQ-bath model. Then we investigate the coefficients of the equations that describe the shift in frequency, diffusive, decoherence, and so on. It is shown that our result on decoherence agrees with experimental one very well as the time is short enough.

Communications in Theoretical Physics•Jul 1, 2008•0 citations

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

Phonon decoherence in quantum dot qubits

Eduardo R. Mucciolo, Serguei Vorojtsov, Harold U. Baranger

The spin of an electron confined into a lateral semiconductor quantum dot has been proposed as a possible physical realization of a qubit. While the spin has the advantage of large decoherence times, operations with more than one qubit will necessarily involve orbital degrees of freedom, namely, charge, which is much more prone to decoherence. There are also alternative quantum dot qubit proposals that are entirely based on charge. We have used a realistic model to quantify the limitations imposed by acoustic phonons on the operation of quantum dot-based qubits. Our treatment includes essential aspects of the setup geometry, wave function profile and materials characteristics. The time dependence of the qubit density matrix is the presence of a phonon bath solved within the Born-Markov approximation. We find that the inclusion of geometric form factors makes the phonon-induced decoherence rates in double dot charge qubits nearly one order of magnitude lower than estimates previously in the literature. Moreover, our theoretical prediction for the quality factor of coherent charge oscillations based on phonon decoherence are higher than the values recently observed experimentally. This allows us to conclude that phonons are not the primary source of decoherence in double quantum dot qubits.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•May 25, 2005•1 citation

Non-Markovian dynamics of double quantum dot charge qubits due to acoustic phonons

Michael Thorwart, Jens Eckel, Eduardo R. Mucciolo

We investigate the dynamics of a double quantum dot charge qubit which is coupled to piezoelectric acoustic phonons, appropriate for GaAs heterostructures. At low temperatures, the phonon bath induces the non-Markovian dynamical behavior of the oscillations between the two charge states of the double quantum dot. Upon applying the numerically exact quasiadiabatic propagator path-integral scheme, the reduced density matrix of the charge qubit is calculated, thereby avoiding the Born-Markov approximation. This allows a systematic study of the dependence of the $Q$ factor on the lattice temperature, on the size of the quantum dots, as well as on the interdot coupling. We calculate the $Q$ factor for a recently realized experimental setup and find that it is two orders of magnitudes larger than the measured value, indicating that the decoherence due to phonons is a subordinate mechanism.

arXiv:cond-mat/0505621•Physical Review B•Dec 16, 2005•63 citations
In this paper, we investigate the decoherence time of a double quantum dot (DQD) charge qubit in three kinds of baths through solving dynamics of the qubit. The dynamics of the qubit is investigated with Redfield master equation. It is shown that the decoherence time of the qubit in Ohmic bath has the same order of magnitude as the experiments reported. When the environment is modeled with the supra-Ohmic bath the decoherence time of the qubit is shorter than the experimental result. And when modeled with the sub-Ohmic bath the decoherence time of the qubit is longer than the experimental result.
In this paper we investigate decoherence times of a double quantum dot (DQD) charge qubit due to it coupling with acoustic phonon baths. We individually consider the acoustic piezoelectric as well as deformation coupling phonon baths in the qubit environment. The decoherence times are calculated with two kinds of methods. One of them is based on the qusiadiabatic propagator path integral (QUAPI) and the other is based on Bloch equations, and two kinds of results are compared. It is shown that the theoretical decoherence times of the DQD charge qubit are shorter than the experimental reported results. It implies that the phonon couplings to the qubit play a subordinate role, resulting in the decoherence of the qubit.
在这篇论文，我们调查一个双量点(DQD ) 的 decoherence 时间在通过解决 qubit 的动力学的三种洗澡的费用 qubit。qubit 的动力学与 Redfield 主人方程被调查。在欧姆的洗澡的 qubit 的 decoherence 时间把象实验的一样的数量级报导，这被显示出。当环境与在上被建模时 -- 欧姆的洗澡 qubit 的 decoherence 时间比试验性的结果短。并且当与亚 Ohmic 洗澡当模特儿时， qubit 的 decoherence 时间比试验性的结果长。
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.
The spin of an electron confined into a lateral semiconductor quantum dot has been proposed as a possible physical realization of a qubit. While the spin has the advantage of large decoherence times, operations with more than one qubit will necessarily involve orbital degrees of freedom, namely, charge, which is much more prone to decoherence. There are also alternative quantum dot qubit proposals that are entirely based on charge. We have used a realistic model to quantify the limitations imposed by acoustic phonons on the operation of quantum dot-based qubits. Our treatment includes essential aspects of the setup geometry, wave function profile and materials characteristics. The time dependence of the qubit density matrix is the presence of a phonon bath solved within the Born-Markov approximation. We find that the inclusion of geometric form factors makes the phonon-induced decoherence rates in double dot charge qubits nearly one order of magnitude lower than estimates previously in the literature. Moreover, our theoretical prediction for the quality factor of coherent charge oscillations based on phonon decoherence are higher than the values recently observed experimentally. This allows us to conclude that phonons are not the primary source of decoherence in double quantum dot qubits.
We investigate the dynamics of a double quantum dot charge qubit which is coupled to piezoelectric acoustic phonons, appropriate for GaAs heterostructures. At low temperatures, the phonon bath induces the non-Markovian dynamical behavior of the oscillations between the two charge states of the double quantum dot. Upon applying the numerically exact quasiadiabatic propagator path-integral scheme, the reduced density matrix of the charge qubit is calculated, thereby avoiding the Born-Markov approximation. This allows a systematic study of the dependence of the QQQ factor on the lattice temperature, on the size of the quantum dots, as well as on the interdot coupling. We calculate the QQQ factor for a recently realized experimental setup and find that it is two orders of magnitudes larger than the measured value, indicating that the decoherence due to phonons is a subordinate mechanism.