Confinement drives valley splitting above 4K in buried silicon quantum wells

• URL: http://arxiv.org/abs/2607.09570v1
• Date: Fri, 10 Jul 2026 16:17:20 GMT
• Title: Confinement drives valley splitting above 4K in buried silicon quantum wells
• Abstract summary: In silicon spin qubits, the nearly degenerate conduction-band valleys create a leakage channel from the single-spin computational basis.<n>Here, we measure the relevant energy scales of single-electron spin qubits in buried silicon quantum wells co-designed for low disorder and high valley splitting.
• Score: 0.410492188035848
• License: http://creativecommons.org/licenses/by-nc-sa/4.0/
• Abstract: Controlling the energy scales of a quantum system is essential for defining robust qubits. In silicon spin qubits, the nearly degenerate conduction-band valleys create a leakage channel from the single-spin computational basis, posing a challenge to scaling and to shuttling-based architectures. Here, we measure the relevant energy scales of single-electron spin qubits in buried silicon quantum wells co-designed for low disorder and high valley splitting. Across a linear array of four quantum dots with an average orbital energy of 2.4(2) meV, we report an average single-electron valley splitting of 0.40(6) meV and an average two-electron singlet-triplet splitting of 0.24(7) meV. In three dots, we observe a strong correlation between valley splitting and orbital energy, with an average linear coefficient of $\approx 0.22$ (meV/meV), demonstrating that electrostatic confinement can increase the valley splitting by several hundred microelectronvolts. In contrast, the remaining dot exhibits the highest valley splitting of 0.76(2) meV and low correlation, suggesting excellent characteristics for spin-qubit operation. Our findings demonstrate that strong confinement can be exploited in buried quantum wells to effectively enhance the valley splitting, thereby establishing a viable path toward the realization of shuttling and sparse-occupation-based architectures in low-disorder heterostructures.

Related papers

• Simulation of exchange coupling effects in double quantum dot FinFET-like structures [43.64338380623755]
  We use a GPU-accelerated Schrdinger-Poisson solver to characterize exchange coupling in a hole spin double-qubit device.<n>We show that our simulation framework is capable of reproducing the magneto-electrostatic behavior of the devices of interest.
  arXiv  Detail & Related papers  (2026-07-09T13:08:37Z)
• Tailoring pure valley-Zeeman spin-orbit coupling in WSe$_2$-encapsulated monolayer graphene [42.39722022913058]
  Engineering proximity effects in twisted van der Waals heterostructures offers a powerful platform for designing electronic properties.<n>We report pure valley-Zeeman spin-orbit coupling in monolayer graphene, achieved by encapsulation between two parallel twisted WSe$$ monolayers.<n>We also demonstrate the ability to completely quench the proximity spin-orbit coupling by tuning the encapsulated geometry.
  arXiv  Detail & Related papers  (2026-06-02T07:43:48Z)
• Quantum Hall Effect at 0.002T [46.680073344221626]
  We demonstrate a significant reduction in external inhomogeneity using a double-layer graphene architecture separated by an ultra-thin hexagonal boron nitride layer.<n>Shubnikov de-Haas oscillations emerge at magnetic fields below 1 mT, while integer quantum Hall features are observed at 0.002T.<n>These results demonstrate the platform's suitability for investigating strongly correlated electronic phases in graphene-based heterostructures.
  arXiv  Detail & Related papers  (2026-01-22T14:40:33Z)
• Strain-Tunable Spin Filtering and Valley Splitting Coexisting with Anomalous Hall Effect in 2D Half-Metallic VSe2/VN Heterostructure: Toward a Unified Spintronic-Valleytronic Platform [0.0]
  A van der Waals heterostructure (VSe2/VN) built from hexagonal VSe2 and hexagonal VN provided robust valley splitting and strong spin selectivity.<n>Results identified VSe2/VN as a practical, strain-tunable platform for integrated valleytronic, spintronic devices.
  arXiv  Detail & Related papers  (2025-11-08T16:43:14Z)
• Mapping of valley-splitting by conveyor-mode spin-coherent electron shuttling [0.0]
  In Si/SiGe heterostructures, the low-lying excited valley state seriously limits operability and scalability of electron spin qubits. We introduce a method for two-dimensional mapping of the local valley splitting using entangled electron spin-pairs as a probe. Our method may become a valuable tool for engineering Si/SiGe heterostructures for scalable quantum computing.
  arXiv  Detail & Related papers  (2023-12-29T17:21:04Z)
• Enhancing the Coherence of Superconducting Quantum Bits with Electric Fields [62.997667081978825]
  We show that qubit coherence can be improved by tuning defects away from the qubit resonance using an applied DC-electric field. We also discuss how local gate electrodes can be implemented in superconducting quantum processors to enable simultaneous in-situ coherence optimization of individual qubits.
  arXiv  Detail & Related papers  (2022-08-02T16:18:30Z)
• Probing the Spatial Variation of the Inter-Valley Tunnel Coupling in a Silicon Triple Quantum Dot [0.0]
  Electrons confined in silicon quantum dots exhibit orbital, spin, and valley degrees of freedom. The degeneracy can be lifted in silicon quantum wells due to strain and electronic confinement.
  arXiv  Detail & Related papers  (2021-01-29T14:08:50Z)
• A singlet triplet hole spin qubit in planar Ge [40.24757332810004]
  GroupIV hole spin qubits have moved into the focus of interest due to the ease of operation and compatibility with Si technology. We demonstrate a hole spin qubit operating at fields below 10 mT, the critical field of Al, by exploiting the large out-of-plane hole g-factors in planar Ge. Results demonstrate that Ge hole singlet-triplet qubits are competing with state-of-the art GaAs and Si singlet-triplet qubits.
  arXiv  Detail & Related papers  (2020-11-27T14:41:08Z)
• Effect of quantum Hall edge strips on valley splitting in silicon quantum wells [0.0]
  We probe the valley splitting dependence on both perpendicular magnetic field $B$ and Hall density. The mobility gap of the valley-split levels increases linearly with $B$ and is strikingly independent of Hall density.
  arXiv  Detail & Related papers  (2020-06-03T14:45:33Z)
• Universal coherence protection in a solid-state spin qubit [95.73841600562527]
  We construct a robust qubit embedded in a decoherence-protected subspace. The qubit is protected from magnetic, electric, and temperature fluctuations. This results in an increase of the qubit's inhomogeneous dephasing time by over four orders of magnitude.
  arXiv  Detail & Related papers  (2020-05-12T22:44:23Z)

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.