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/0207257 · Physical review. B, Condensed matter

Adiabatic transfer of electrons in coupled quantum dots

Tobias Brandes, Till Vorrath

Published Aug 30, 2002• 111 citations
arXivHTMLPDF

Abstract

We investigate the influence of dissipation on one- and two-qubit rotations in coupled semiconductor quantum dots, using a (pseudo-)spin-boson model with adiabatically varying parameters. For weak dissipation, we solve a master equation, compare with direct perturbation theory, and derive an expression for the ``fidelity loss'' during a simple operation that adiabatically moves an electron between two coupled dots. We discuss the possibility of visualizing coherent quantum oscillations in electron ``pump'' currents, combining quantum adiabaticity and Coulomb blockade. In two-qubit spin-swap operations where the role of intermediate charge states has been discussed recently, we apply our formalism to calculate the fidelity loss due to charge tunneling between two dots.

DOI
10.1103/physrevb.66.075341

Related papers

Adiabatic electron charge transfer between two quantum dots in presence of 1 / f noise

Jan A. Krzywda, Łukasz Cywiński

Controlled adiabatic transfer of a single electron through a chain of quantum dots has been recently achieved in GaAs and Si/SiGe based quantum dots, opening prospects for turning stationary spin qubits into mobile ones and solving in this way the problem of long-distance communication between quantum registers in a scalable quantum computing architecture based on quantum dots. We consider theoretically the process of such an electron transfer between two tunnel-coupled quantum dots, focusing on control by slowly varying the detuning of energy levels in the dots. We take into account the fluctuations in detuning caused by $1/f$-type noise that is ubiquitous in semiconductor nanostructures and analyze their influence on probability of successful transfer of an electron in a spin eigenstate. With numerical and analytical calculations we show that probability of electron not being transferred due to $1/{f}^{\ensuremath{\beta}}$ noise in detuning is $\ensuremath{\propto}\phantom{\rule{0.16em}{0ex}}{\ensuremath{\sigma}}^{2}{t}^{\ensuremath{\beta}\ensuremath{-}1}/v$, where $\ensuremath{\sigma}$ characterizes the noise amplitude, $t$ is the interdot tunnel coupling, and $v$ is the detuning sweep rate. Interestingly, this means that the noise-induced errors in charge transfer are independent of $t$ for $1/f$ noise. For realistic parameters taken from experiments on silicon-based quantum dots, we obtain the minimal probability of charge transfer failure between a pair of dots is limited by $1/f$ noise in detuning to be the on the order of 0.01. This means that in order to reliably transfer charges across many quantum dots, charge noise in the devices should be further suppressed, or tunnel couplings should be increased, in order to allow for faster transfer (and less exposure to noise), while not triggering the deterministic Landau-Zener excitation.

arXiv:1909.11780•Physical review. B./Physical review. B•Jan 15, 2020•28 citations

Semiconductor quantum dots for electron spin qubits

Wilfred G. van der Wiel, Michael P. Stopa, Tetsuo Kodera +2 more

We report on our recent progress in applying semiconductor quantum dots for spin-based quantum computation, as proposed by Loss and DiVincenzo (1998 Phys. Rev. A 57 120). For the purpose of single-electron spin resonance, we study different types of single quantum dot devices that are designed for the generation of a local ac magnetic field in the vicinity of the dot. We observe photon-assisted tunnelling as well as pumping due to the ac voltage induced by the ac current driven through a wire in the vicinity of the dot, but no evidence for ESR so far. Analogue concepts for a double quantum dot and the hydrogen molecule are discussed in detail. Our experimental results in laterally coupled vertical double quantum dot device show that the Heitler–London model forms a good approximation of the two-electron wavefunction. The exchange coupling constant J is estimated. The relevance of this system for two-qubit gates, in particular the SWAP operation, is discussed. Density functional calculations reveal the importance of the gate electrode geometry in lateral quantum dots for the tunability of J in realistic two-qubit gates.

New Journal of Physics•Feb 21, 2006•37 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

Adiabatic quantum state transfer in a semiconductor quantum-dot spin chain

Yadav P. Kandel, Haifeng Qiao, Saeed Fallahi +3 more

Semiconductor quantum-dot spin qubits are a promising platform for quantum computation, because they are scalable and possess long coherence times. In order to realize this full potential, however, high-fidelity information transfer mechanisms are required for quantum error correction and efficient algorithms. Here, we present evidence of adiabatic quantum-state transfer in a chain of semiconductor quantum-dot electron spins. By adiabatically modifying exchange couplings, we transfer single- and two-spin states between distant electrons in less than 127 ns. We also show that this method can be cascaded for spin-state transfer in long spin chains. Based on simulations, we estimate that the probability to correctly transfer single-spin eigenstates and two-spin singlet states can exceed 0.95 for the experimental parameters studied here. In the future, state and process tomography will be required to verify the transfer of arbitrary single qubit states with a fidelity exceeding the classical bound. Adiabatic quantum-state transfer is robust to noise and pulse-timing errors. This method will be useful for initialization, state distribution, and readout in large spin-qubit arrays for gate-based quantum computing. It also opens up the possibility of universal adiabatic quantum computing in semiconductor quantum-dot spin qubits.

arXiv:2007.03869•Nature Communications•Apr 12, 2021•62 citations

Dynamics of interacting transport qubits

Christian Nietner, Gernot Schaller, Christina Pöltl +1 more

We investigate the electronic transport through two parallel double quantum dots coupled both capacitively and via a perpendicularly aligned charge qubit. The presence of the qubit leads to a modification of the coherent tunnel amplitudes of each double quantum dot. We study the influence of the qubit on the electronic steady-state currents through the system, the entanglement between the transport double quantum dots, and the back-action on the charge qubit. We use a Born-Markov secular quantum master equation for the system. The obtained currents show signatures of the qubit. The stationary qubit state may be tuned and even rendered pure by applying suitable voltages. In the Coulomb diamonds, it is also possible to stabilize pure entangled states of the transport double quantum dots.

arXiv:1204.2978•Physical Review B•Jun 15, 2012•7 citations

Interplay of charge noise and coupling to phonons in adiabatic electron transfer between quantum dots

Jan A. Krzywda, Łukasz Cywiński

Long-distance transfer of quantum information in architectures based on quantum dot spin qubits will be necessary for their scalability. One way of achieving this goal is to simply move the electron between two quantum registers. Precise control over the process of shuttling such a single electron through a chain of tunnel-coupled quantum dots is possible when interdot energy detunings are changed adiabatically. The deterministic character of shuttling is, however, endangered by the open nature of the system, as the transferred electron is coupled to thermal reservoirs: sources of fluctuations of electric fields and lattice vibrations. We present a comprehensive analysis showing how the electron transfer between two voltage-controlled quantum dots is affected by electron-phonon scattering and interaction with sources of $1/f$ and Johnson charge noise in both detuning and tunnel coupling. The electron-phonon scattering turns out to be irrelevant in Si quantum dots, with charge noise dominating the dynamics of the system at slow detuning sweep, when the electron spends more time delocalized between the dots (i.e., near the anticrossing of the tunnel-coupled states). Competition between the effects of charge noise and the Landau-Zener effect leads to an existence of an optimal detuning sweep rate, leading to minimal probability of leaving the electron behind. In GaAs quantum dots, on the other hand, piezoelectric coupling to phonons is strong enough to make the processes of interdot transfer assisted by phonon emission and absorption dominate over transitions caused by charge noise. The probability of leaving the electron behind then depends monotonically on detuning the sweep rate over a broad range of rates, and values much smaller than in silicon can be obtained for slow sweeps. However, after taking into account limitations on transfer time imposed by the need for preservation of a shuttled electron's spin coherence, the minimal probabilities of leaving the electron behind in both GaAs- and Si-based double quantum dots turn out to be of the same order of magnitude. Bringing them down below ${10}^{\ensuremath{-}3}$ requires temperatures $\ensuremath{\le}100$ mK and tunnel couplings above $20\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{eV}$.

arXiv:2104.07581•Physical review. B./Physical review. B•Aug 20, 2021•28 citations
We investigate the influence of dissipation on one- and two-qubit rotations in coupled semiconductor quantum dots, using a (pseudo-)spin-boson model with adiabatically varying parameters. For weak dissipation, we solve a master equation, compare with direct perturbation theory, and derive an expression for the fidelity loss'' during a simple operation that adiabatically moves an electron between two coupled dots. We discuss the possibility of visualizing coherent quantum oscillations in electron pump'' currents, combining quantum adiabaticity and Coulomb blockade. In two-qubit spin-swap operations where the role of intermediate charge states has been discussed recently, we apply our formalism to calculate the fidelity loss due to charge tunneling between two dots.
Controlled adiabatic transfer of a single electron through a chain of quantum dots has been recently achieved in GaAs and Si/SiGe based quantum dots, opening prospects for turning stationary spin qubits into mobile ones and solving in this way the problem of long-distance communication between quantum registers in a scalable quantum computing architecture based on quantum dots. We consider theoretically the process of such an electron transfer between two tunnel-coupled quantum dots, focusing on control by slowly varying the detuning of energy levels in the dots. We take into account the fluctuations in detuning caused by 1/f1/f1/f-type noise that is ubiquitous in semiconductor nanostructures and analyze their influence on probability of successful transfer of an electron in a spin eigenstate. With numerical and analytical calculations we show that probability of electron not being transferred due to $1/{f}^{\ensuremath{\beta}}$ noise in detuning is $\ensuremath{\propto}\phantom{\rule{0.16em}{0ex}}{\ensuremath{\sigma}}^{2}{t}^{\ensuremath{\beta}\ensuremath{-}1}/v$, where $\ensuremath{\sigma}$ characterizes the noise amplitude, ttt is the interdot tunnel coupling, and vvv is the detuning sweep rate. Interestingly, this means that the noise-induced errors in charge transfer are independent of ttt for 1/f1/f1/f noise. For realistic parameters taken from experiments on silicon-based quantum dots, we obtain the minimal probability of charge transfer failure between a pair of dots is limited by 1/f1/f1/f noise in detuning to be the on the order of 0.01. This means that in order to reliably transfer charges across many quantum dots, charge noise in the devices should be further suppressed, or tunnel couplings should be increased, in order to allow for faster transfer (and less exposure to noise), while not triggering the deterministic Landau-Zener excitation.
We report on our recent progress in applying semiconductor quantum dots for spin-based quantum computation, as proposed by Loss and DiVincenzo (1998 Phys. Rev. A 57 120). For the purpose of single-electron spin resonance, we study different types of single quantum dot devices that are designed for the generation of a local ac magnetic field in the vicinity of the dot. We observe photon-assisted tunnelling as well as pumping due to the ac voltage induced by the ac current driven through a wire in the vicinity of the dot, but no evidence for ESR so far. Analogue concepts for a double quantum dot and the hydrogen molecule are discussed in detail. Our experimental results in laterally coupled vertical double quantum dot device show that the Heitler–London model forms a good approximation of the two-electron wavefunction. The exchange coupling constant J is estimated. The relevance of this system for two-qubit gates, in particular the SWAP operation, is discussed. Density functional calculations reveal the importance of the gate electrode geometry in lateral quantum dots for the tunability of J in realistic two-qubit gates.
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.
Semiconductor quantum-dot spin qubits are a promising platform for quantum computation, because they are scalable and possess long coherence times. In order to realize this full potential, however, high-fidelity information transfer mechanisms are required for quantum error correction and efficient algorithms. Here, we present evidence of adiabatic quantum-state transfer in a chain of semiconductor quantum-dot electron spins. By adiabatically modifying exchange couplings, we transfer single- and two-spin states between distant electrons in less than 127 ns. We also show that this method can be cascaded for spin-state transfer in long spin chains. Based on simulations, we estimate that the probability to correctly transfer single-spin eigenstates and two-spin singlet states can exceed 0.95 for the experimental parameters studied here. In the future, state and process tomography will be required to verify the transfer of arbitrary single qubit states with a fidelity exceeding the classical bound. Adiabatic quantum-state transfer is robust to noise and pulse-timing errors. This method will be useful for initialization, state distribution, and readout in large spin-qubit arrays for gate-based quantum computing. It also opens up the possibility of universal adiabatic quantum computing in semiconductor quantum-dot spin qubits.
We investigate the electronic transport through two parallel double quantum dots coupled both capacitively and via a perpendicularly aligned charge qubit. The presence of the qubit leads to a modification of the coherent tunnel amplitudes of each double quantum dot. We study the influence of the qubit on the electronic steady-state currents through the system, the entanglement between the transport double quantum dots, and the back-action on the charge qubit. We use a Born-Markov secular quantum master equation for the system. The obtained currents show signatures of the qubit. The stationary qubit state may be tuned and even rendered pure by applying suitable voltages. In the Coulomb diamonds, it is also possible to stabilize pure entangled states of the transport double quantum dots.
Long-distance transfer of quantum information in architectures based on quantum dot spin qubits will be necessary for their scalability. One way of achieving this goal is to simply move the electron between two quantum registers. Precise control over the process of shuttling such a single electron through a chain of tunnel-coupled quantum dots is possible when interdot energy detunings are changed adiabatically. The deterministic character of shuttling is, however, endangered by the open nature of the system, as the transferred electron is coupled to thermal reservoirs: sources of fluctuations of electric fields and lattice vibrations. We present a comprehensive analysis showing how the electron transfer between two voltage-controlled quantum dots is affected by electron-phonon scattering and interaction with sources of 1/f1/f1/f and Johnson charge noise in both detuning and tunnel coupling. The electron-phonon scattering turns out to be irrelevant in Si quantum dots, with charge noise dominating the dynamics of the system at slow detuning sweep, when the electron spends more time delocalized between the dots (i.e., near the anticrossing of the tunnel-coupled states). Competition between the effects of charge noise and the Landau-Zener effect leads to an existence of an optimal detuning sweep rate, leading to minimal probability of leaving the electron behind. In GaAs quantum dots, on the other hand, piezoelectric coupling to phonons is strong enough to make the processes of interdot transfer assisted by phonon emission and absorption dominate over transitions caused by charge noise. The probability of leaving the electron behind then depends monotonically on detuning the sweep rate over a broad range of rates, and values much smaller than in silicon can be obtained for slow sweeps. However, after taking into account limitations on transfer time imposed by the need for preservation of a shuttled electron's spin coherence, the minimal probabilities of leaving the electron behind in both GaAs- and Si-based double quantum dots turn out to be of the same order of magnitude. Bringing them down below ${10}^{\ensuremath{-}3}$ requires temperatures $\ensuremath{\le}100$ mK and tunnel couplings above $20\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{eV}$.