Control-Noise Trade-offs in Industrially Integrated ${}^{28}\mathrm{Si}/\mathrm{SiGe}$ Spin-1/2 Qubits
Authors: Leon C. Camenzind, Ik Kyeong Jin, Yi-Hsien Wu, Akito Noiri, Kenta Takeda, Takashi Nakajima, Takashi Kobayashi, Giordano Scappucci, Seigo Tarucha
Abstract
Scaling silicon spin qubits to fault-tolerant processors requires semiconductor foundry integration, yet it remains unclear how industrial fabrication and dense device integration affect qubit control and noise. Here we study ${}^{28}\mathrm{Si}/\mathrm{SiGe}$ electron spin-1/2 qubits fabricated using Intel's industry-compatible 300 mm process and incorporating micromagnets for electrically driven spin resonance, using a high-performance device fabricated in the RIKEN research cleanroom as a reference. Primitive $π/2$-gate fidelities reach the 99.99% level in the Intel devices, which also exhibit longer idle coherence, weaker low-frequency correlations and reduced qubit-to-qubit variability across several measured characteristics. In the present Intel devices, the micromagnets are integrated inline with the back-end-of-line (BEOL) contact routing, with their separation from the quantum well set through the vertical stack design. Relative to the reference, their larger separation contributes to weaker longitudinal and transverse magnetic-field gradients. The weaker longitudinal gradient suppresses the conversion of charge noise into qubit-frequency fluctuations, whereas the weaker transverse gradient reduces electrically driven spin-resonance efficiency and makes drive-dependent errors relevant at lower Rabi frequencies. Additional BEOL routing and metal levels required for two-dimensional arrays make such placement decisions increasingly consequential when scaling. These results establish an integration-level control-noise trade-off linking micromagnet placement within densely routed layouts to achievable gate performance, while very high-fidelity operation remains possible in industrially fabricated devices.
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Simultaneous high-fidelity single-qubit gates in a spin qubit arrayYi-Hsien Wu, L. Camenzind, Patrick Butler et al. · 2025 · Nature Physics · cited 59 times · Not summarized yet
Simultaneous high-fidelity single-qubit gates identifies microwave-induced a.c.-Stark shifts and mitigates them with pairwise phase calibration in a silicon spin-qubit array.
Abstract
Silicon spin qubits offer a promising path to scalable quantum computing due to their compatibility with industrial semiconductor manufacturing. A key requirement for scaling quantum processors is the ability to perform high-fidelity operations in parallel across many qubits. However, simultaneous control remains a major challenge in silicon devices, as fidelities typically degrade under parallel operation. Here we identify microwave-drive-induced a.c.-Stark shifts as the dominant source of this degradation in a five-qubit silicon spin array. We address this by introducing a scalable mitigation protocol based solely on pairwise phase calibrations. Using tailored control pulses on a shared co…
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Electrical control of a long-lived spin qubit in a Si/SiGe quantum dot.E. Kawakami, P. Scarlino, D. Ward et al. · 2014 · Nature Nanotechnology · cited 489 times · Not summarized yet
Electrical control of a long-lived spin qubit demonstrates all-electrical control of a Si/SiGe spin using a micromagnet-generated transverse field gradient.
Abstract
Nanofabricated quantum bits permit large-scale integration but usually suffer from short coherence times due to interactions with their solid-state environment. The outstanding challenge is to engineer the environment so that it minimally affects the qubit, but still allows qubit control and scalability. Here, we demonstrate a long-lived single-electron spin qubit in a Si/SiGe quantum dot with all-electrical two-axis control. The spin is driven by resonant microwave electric fields in a transverse magnetic field gradient from a local micromagnet, and the spin state is read out in the single-shot mode. Electron spin resonance occurs at two closely spaced frequencies, which we attribute to two…
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Optimized electrical control of a Si/SiGe spin qubit in the presence of an induced frequency shiftK. Takeda, J. Yoneda, T. Otsuka et al. · 2018 · npj Quantum Information · cited 63 times · Not summarized yet
Optimized electrical control studies microwave-induced resonance shifts in Si/SiGe spin qubits and improves control fidelity through pulse optimization.
Abstract
Electron spins confined in quantum dots are an attractive system to realize high-fidelity qubits owing to their long coherence time. With the prolonged spin coherence time, however, the control fidelity can be limited by systematic errors rather than decoherence, making characterization and suppression of their influence crucial for further improvement. Here we report that the control fidelity of Si/SiGe spin qubits can be limited by the microwave-induced frequency shift of electric dipole spin resonance and it can be improved by optimization of control pulses. As we increase the control microwave amplitude, we observe a shift of the qubit resonance frequency, in addition to the increasing R…
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High-fidelity single-spin shuttling in siliconMaxim De Smet, Yuta Matsumoto, Anne-Marije J. Zwerver et al. · 2024 · Mesoscale and Nanoscale Physics · cited 107 times · AI summary available
High-fidelity single-spin shuttling demonstrates electron transport in isotopically purified silicon, addressing connectivity through physical movement rather than micromagnet placement.
Abstract
The computational power and fault-tolerance of future large-scale quantum processors derive in large part from the connectivity between the qubits. One approach to increase connectivity is to engineer qubit-qubit interactions at a distance. Alternatively, the connectivity can be increased by physically displacing the qubits. This has been explored in trapped-ion experiments and using neutral atoms trapped with optical tweezers. For semiconductor spin qubits, several studies have investigated spin coherent shuttling of individual electrons, but high-fidelity transport over extended distances remains to be demonstrated. Here we report shuttling of an electron inside an isotopically purified Si…
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Industry-compatible silicon spin-qubit unit cells exceeding 99% fidelityP. Steinacker, N. Dumoulin Stuyck, W. Lim et al. · 2024 · Nature · cited 141 times · Not summarized yet
Industry-compatible silicon spin-qubit unit cells tests whether foundry-fabricated silicon qubits can achieve high-fidelity operation, also examining industrial integration and qubit performance.
Abstract
Among the many types of qubit presently being investigated for a future quantum computer, silicon spin qubits with millions of qubits on a single chip are uniquely positioned to enable quantum computing. However, it has not been clear whether the outstanding high-fidelity operations and long coherence times shown by silicon spin qubits fabricated in academic settings1, 2, 3, 4, 5, 6, 7–8 can be reliably reproduced when the qubits are manufactured in a semiconductor foundry9, 10–11. Here we show precise qubit operation of silicon two-qubit devices made with standard semiconductor tooling in a 300-mm foundry environment. Of the key metrics, single- and two-qubit control fidelities exceed 99% f…
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Spin-qubit control with a milli-kelvin CMOS chipSamuel K. Bartee, W. Gilbert, K. Zuo et al. · 2025 · Nature · cited 64 times · Not summarized yet
Spin-qubit control with a milli-kelvin CMOS chip studies integrating control electronics near silicon spin qubits and the resulting risks of heat and crosstalk.
Abstract
A key virtue of spin qubits is their sub-micron footprint, enabling a single silicon chip to host the millions of qubits required to execute useful quantum algorithms with error correction1, 2–3. However, with each physical qubit needing multiple control lines, a fundamental barrier to scale is the extreme density of connections that bridge quantum devices to their external control and readout hardware4, 5–6. A promising solution is to co-locate the control system proximal to the qubit platform at milli-kelvin temperatures, wired up by miniaturized interconnects7, 8, 9–10. Even so, heat and crosstalk from closely integrated control have the potential to degrade qubit performance, particularl…
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Baseband control of single-electron silicon spin qubits in two dimensionsF. K. Unseld, B. Undseth, E. Raymenants et al. · 2024 · cited 31 times · Not summarized yet
Baseband control replaces micromagnet-enabled microwave driving with hopping-spin control in a two-dimensional silicon array.
Abstract
Micromagnet-enabled electric-dipole spin resonance (EDSR) is an established method of high-fidelity single-spin control in silicon. However, the resulting architectural limitations have restrained silicon quantum processors to one-dimensional arrays, and heating effects from the associated microwave dissipation exacerbates crosstalk during multi-qubit operations. In contrast, qubit control based on hopping spins has recently emerged as a compelling primitive for high-fidelity baseband control in sparse two-dimensional hole arrays in germanium. In this work, we commission a $^{28}$Si/SiGe 2x2 quantum dot array both as a four-qubit device with pairwise exchange interactions using established E…
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Scaling of silicon spin qubits under correlated noiseJ. S. Rojas-Arias, L. Camenzind, Yi-Hsien Wu et al. · 2026 · cited 6 times · Not summarized yet
Scaling of silicon spin qubits under correlated noise quantifies spatial noise correlations in a five-qubit array, a central noise and scalability issue in this study.
Abstract
The path to fault-tolerant quantum computing hinges on hardware that scales while remaining compatible with quantum error correction (QEC). Silicon spin qubits are a leading hardware candidate because they combine industrial fabrication compatibility with a nanoscale footprint that could accommodate millions of qubits on a chip. However, their suitability for QEC remains uncertain since spatially correlated noise naturally emerges from the resulting close proximity of qubits. These correlations increase the likelihood of simultaneous errors and erode the redundancy that QEC depends on. Here we quantify the spatial extent of noise correlations in a five-qubit silicon array and assess their im…
Prior work it builds on
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Noise-correlation spectrum for a pair of spin qubits in siliconJ. Yoneda, J. S. Rojas-Arias, P. Stano et al. · 2022 · Nature Physics · cited 94 times · Not summarized yet
Noise-correlation spectrum measures correlated fluctuations between neighbouring silicon spin qubits, which this study also characterizes across its devices.
Abstract
Semiconductor qubits have a small footprint and so are appealing for building densely integrated quantum processors. However, fabricating them at high densities raises the issue of noise correlated across different qubits, which is of practical concern for scalability and fault tolerance. Here, we analyse and quantify the degree of noise correlation in a pair of neighbouring silicon spin qubits around 100 nm apart. We observe strong interqubit noise correlations with a correlation strength as large as 0.7 at around 1 Hz, even in the regime where the spin–spin exchange interaction contributes negligibly. We find that fluctuations of single-spin precession rates are strongly correlated with ex…
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Qubits made by advanced semiconductor manufacturingA. Zwerver, T. Krähenmann, T. Watson et al. · 2021 · Nature Electronics · cited 390 times · Not summarized yet
Qubits made by advanced semiconductor manufacturing demonstrates silicon quantum-dot fabrication in a 300 mm industrial facility, establishing the manufacturing context examined here.
Abstract
Silicon spin qubits can be fabricated in a 300 mm semiconductor manufacturing facility using all-optical lithography and fully industrial processing. Full-scale quantum computers require the integration of millions of qubits, and the potential of using industrial semiconductor manufacturing to meet this need has driven the development of quantum computing in silicon quantum dots. However, fabrication has so far relied on electron-beam lithography and, with a few exceptions, conventional lift-off processes that suffer from low yield and poor uniformity. Here we report quantum dots that are hosted at a ^28Si/^28SiO_2 interface and fabricated in a 300 mm semiconductor manufacturing facility usi…
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High-fidelity spin qubit operation and algorithmic initialization above 1 KJ. Y. Huang, R.-Y. Su, W. Lim et al. · 2023 · Nature · cited 162 times · Not summarized yet
High-fidelity spin qubit operation and algorithmic initialization above 1 K examines silicon spin-qubit performance at elevated temperatures rather than fabrication-related control-noise trade-offs.
Abstract
The encoding of qubits in semiconductor spin carriers has been recognized as a promising approach to a commercial quantum computer that can be lithographically produced and integrated at scale1–10. However, the operation of the large number of qubits required for advantageous quantum applications11–13 will produce a thermal load exceeding the available cooling power of cryostats at millikelvin temperatures. As the scale-up accelerates, it becomes imperative to establish fault-tolerant operation above 1 K, at which the cooling power is orders of magnitude higher14–18. Here we tune up and operate spin qubits in silicon above 1 K, with fidelities in the range required for fault-tolerant operati…
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A fault-tolerant addressable spin qubit in a natural silicon quantum dotK. Takeda, J. Kamioka, T. Otsuka et al. · 2016 · Science Advances · cited 232 times · Not summarized yet
A fault-tolerant addressable spin qubit in a natural silicon quantum dot studies high-fidelity operation despite nuclear-spin dephasing in natural silicon.
Abstract
This is the first experimental demonstration of a fault-tolerant spin qubit in industry-compatible isotopically natural silicon. Fault-tolerant quantum computing requires high-fidelity qubits. This has been achieved in various solid-state systems, including isotopically purified silicon, but is yet to be accomplished in industry-standard natural (unpurified) silicon, mainly as a result of the dephasing caused by residual nuclear spins. This high fidelity can be achieved by speeding up the qubit operation and/or prolonging the dephasing time, that is, increasing the Rabi oscillation quality factor Q (the Rabi oscillation decay time divided by the π rotation time). In isotopically purified sil…
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Robust micromagnet design for fast electrical manipulations of single spins in quantum dotsJ. Yoneda, T. Otsuka, T. Takakura et al. · 2015 · Applied Physics Express · cited 71 times · Not summarized yet
Robust micromagnet design models and tests stray-field gradients for fast electrical spin manipulation, relevant to the gradients and control trade-offs studied here.
Abstract
Tailoring spin coupling to electric fields is central to spintronics and spin-based quantum information processing. We present an optimal micromagnet design that produces appropriate stray magnetic fields to mediate fast electrical spin manipulations in nanodevices. We quantify the practical requirements for spatial field inhomogeneity and tolerance for misalignment with spins, and propose a design scheme to improve the spin-rotation frequency (to exceed 50 MHz in GaAs nanostructures). We then validate our design by experiments in separate devices. Our results will open a route to rapidly control solid-state electron spins with limited lifetimes and to study coherent spin dynamics in solids.…
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