Smooth velocity shuttling for suppressing valley excitations in disordered Si/SiGe quantum dots

• URL: http://arxiv.org/abs/2606.01541v1
• Date: Mon, 01 Jun 2026 01:42:52 GMT
• Title: Smooth velocity shuttling for suppressing valley excitations in disordered Si/SiGe quantum dots
• Abstract summary: In silicon qubits, non-adiabatic transitions to excited valley states cause spin dephasing.<n>We propose a smooth velocity shuttling protocol to suppress these valley excitations.<n>Our results underscore that this simple, control-level velocity shaping provides a robust pathway toward high-fidelity spin transport.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Coherent electron shuttling is a key requirement for realizing scalable silicon quantum computing architectures. However, in silicon qubits, the existence of nearly degenerate conduction-band valleys poses a significant challenge because non-adiabatic transitions to excited valley states cause spin dephasing via spin-valley mixing. In this paper, we propose a smooth velocity shuttling protocol to suppress these valley excitations. By mapping the time-domain design of the shuttling velocity profile onto the design problem of window functions in signal processing, we establish an analytical and intuitive design guideline that does not require computationally expensive numerical optimization. We demonstrate that the high-frequency sidelobes of the shuttling velocity spectrum can be effectively suppressed by applying a frequency-modulated gate voltage based on the Tukey window. Through numerical simulations incorporating realistic spatial randomness of the valley landscape, we show that the proposed smooth velocity control significantly reduces the average spin infidelity in the moderate-to-low disorder regime ($|Δ_0|/σ_Δ\simeq \mathcal{O}(1)$). Furthermore, we clarify that in devices designed with a large deterministic valley coupling $|Δ_0|$, combining it with this smoothing technique improves robustness against valley disorder. Our results underscore that this simple, control-level velocity shaping provides a robust pathway toward high-fidelity spin transport in large-scale silicon quantum processors.

Related papers

• Taming Curvature: Architecture Warm-Up for Stable Transformer Training [52.6838951211596]
  We introduce a fast online estimator of the largest (preconditioned) Hessian eigenvalue (i.e., curvature) based on a warm-started variant for power with Hessian-vector products.<n>We find that training instabilities coincide with surges in preconditioned curvature and that curvature grows with depth.<n> Experiments on large Transformers validate that our approach enables efficient curvature tracking and reduces instabilities.
  arXiv  Detail & Related papers  (2026-06-15T14:16:56Z)
• An Analytical Approach to Design Space Exploration for Cavity-Mediated Quantum State Transfer in Multi-core Architectures [1.2965006649422552]
  We derive exact analytical expressions for the state transfer dynamics of a two-qubit system coupled via a waveguide.<n>Our framework provides a significant computational speedup compared to standard numerical solvers.<n>We propose a simplified latency model and an efficiency-based function to enable rapid identification of optimal operating points.
  arXiv  Detail & Related papers  (2026-04-30T10:01:24Z)
• Suppressing Si Valley Excitation and Valley-Induced Spin Dephasing for Long-Distance Shuttling [0.0]
  We present a scalable protocol for suppressing errors during electron spin shuttling in silicon quantum dots. An optimization refines the shuttling velocity profile over a single small segment of the shuttling path. This protocol offers a chip-scale solution for high-fidelity quantum transport in silicon spin-based quantum computing devices.
  arXiv  Detail & Related papers  (2024-11-18T16:17:24Z)
• Long distance spin shuttling enabled by few-parameter velocity optimization [37.69303106863453]
  Spin qubit shuttling via moving conveyor-mode quantum dots in Si/SiGe offers a promising route to scalable miniaturized quantum computing. Recent modeling of dephasing via valley degrees of freedom and well disorder dictate a slow shutting speed which seems to limit errors to above correction thresholds if not mitigated. We show that typical errors for 10 $mu$m shuttling at constant speed results in O(1) error, using fast, automatically differentiable numerics and including improved disorder modeling and potential noise ranges.
  arXiv  Detail & Related papers  (2024-09-11T20:21:45Z)
• Laser-field detuning assisted optimization of exciton valley dynamics in monolayer WSe$_2$: Geometric quantum speed limit [0.1474723404975345]
  We construct a comprehensive model, involving both intra- and intervalley channels of excitons in monolayer WSe$tronic. We propose two optimal control schemes aiming to reduce the evolution time of valley dynamics reaching the target state, along with to boost the evolution speed over a period of time. Our work opens a new paradigm for optically excitonic physics in valley tuning applications, and may also offer solutions to some urgent problems such as speed limit of information transmission in qubit.
  arXiv  Detail & Related papers  (2024-01-14T03:21:47Z)
• High-fidelity spin qubit shuttling via large spin-orbit interaction [0.0]
  We show that the large inhomogeneity of the Zeeman field stabilizes the coherence of a moving spin state. Our findings are generally applicable to a wide range of setups and could pave the way toward large-scale quantum processors.
  arXiv  Detail & Related papers  (2023-11-27T16:13:16Z)
• Completely Positive Map for Noisy Driven Quantum Systems Derived by Keldysh Expansion [39.58317527488534]
  We introduce a decoherence model based on the Keldysh formalism. This formalism allows us to include non-periodic drives and correlated quantum noise in our model. We demonstrate that this strategy generates pulses that mitigate correlated quantum noise in qubit state-transfer and gate operations.
  arXiv  Detail & Related papers  (2023-03-20T23:05:24Z)
• Digital noise spectroscopy with a quantum sensor [57.53000001488777]
  We introduce and experimentally demonstrate a quantum sensing protocol to sample and reconstruct the auto-correlation of a noise process. Walsh noise spectroscopy method exploits simple sequences of spin-flip pulses to generate a complete basis of digital filters. We experimentally reconstruct the auto-correlation function of the effective magnetic field produced by the nuclear-spin bath on the electronic spin of a single nitrogen-vacancy center in diamond.
  arXiv  Detail & Related papers  (2022-12-19T02:19:35Z)
• Quantum emulation of the transient dynamics in the multistate Landau-Zener model [50.591267188664666]
  We study the transient dynamics in the multistate Landau-Zener model as a function of the Landau-Zener velocity. Our experiments pave the way for more complex simulations with qubits coupled to an engineered bosonic mode spectrum.
  arXiv  Detail & Related papers  (2022-11-26T15:04:11Z)
• Simulating the Mott transition on a noisy digital quantum computer via Cartan-based fast-forwarding circuits [62.73367618671969]
  Dynamical mean-field theory (DMFT) maps the local Green's function of the Hubbard model to that of the Anderson impurity model. Quantum and hybrid quantum-classical algorithms have been proposed to efficiently solve impurity models. This work presents the first computation of the Mott phase transition using noisy digital quantum hardware.
  arXiv  Detail & Related papers  (2021-12-10T17:32:15Z)
• Continuous-time dynamics and error scaling of noisy highly-entangling quantum circuits [58.720142291102135]
  We simulate a noisy quantum Fourier transform processor with up to 21 qubits. We take into account microscopic dissipative processes rather than relying on digital error models. We show that depending on the dissipative mechanisms at play, the choice of input state has a strong impact on the performance of the quantum algorithm.
  arXiv  Detail & Related papers  (2021-02-08T14:55:44Z)
• Fast and differentiable simulation of driven quantum systems [58.720142291102135]
  We introduce a semi-analytic method based on the Dyson expansion that allows us to time-evolve driven quantum systems much faster than standard numerical methods. We show results of the optimization of a two-qubit gate using transmon qubits in the circuit QED architecture.
  arXiv  Detail & Related papers  (2020-12-16T21:43:38Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.