Engineering long spin coherence times of spin–orbit qubits in silicon

Kobayashi, Takashi; Salfi, Joe; Chua, Cassandra; Heijden, Joost van der; House, Matthew; Culcer, Dimitrie; Hutchison, W. D.; Johnson, Brett C.; McCallum, Jeffrey C.; Riemann, H.; Абросимов, Н. В.; Becker, Peter; Pohl, H.‐J.; Simmons, M. Y.; Rogge, Sven

doi:10.1038/s41563-020-0743-3

Cited by 55 publications

(27 citation statements)

References 38 publications

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“…Sweet spots where d g ↔ /dV G = 0 V −1 are important for qubits since the coupling between the spin and electric fluctuations in the voltage source (V G ) are suppressed. Minimizing the effects of charge noise is critical for hole-spin qubits since the coherence time T * 2 of hole spins in group IV quantum dots is primarily limited by electrical noise [14,53]. Furthermore, recent theoretical work shows that it is possible to engineer sweet spots where the dominant charge dephasing mechanism is suppressed while still allowing high-speed electrical qubit control [54][55][56].…”

Section: B Electrical Modulation Of the N = 1 Hole G Factormentioning

confidence: 99%

Electrical control of the g tensor of the first hole in a silicon MOS quantum dot

et al. 2021

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Single holes confined in semiconductor quantum dots are a promising platform for spin-qubit technology, due to the electrical tunability of the g factor of holes. However, the underlying mechanisms that enable electric spin control remain unclear due to the complexity of hole-spin states. Here, we study the underlying hole-spin physics of the first hole in a silicon planar metal-oxide-semiconductor (MOS) quantum dot. We show that nonuniform electrode-induced strain produces nanometer-scale variations in the heavy-hole-light-hole (HH-LH) splitting. Importantly, we find that this nonuniform strain causes the HH-LH splitting to vary by up to 50% across the active region of the quantum dot. We show that local electric fields can be used to displace the hole relative to the nonuniform strain profile, allowing a mechanism for electric modulation of the hole g tensor. Using this mechanism, we demonstrate tuning of the hole g factor by up to 500%. In addition, we observe a potential sweet spot where dg (110) /dV = 0, offering a configuration to suppress spin decoherence caused by electrical noise. These results open a path towards a technology involving engineering of nonuniform strains to optimize spin-based devices.

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Section: B Electrical Modulation Of the N = 1 Hole G Factormentioning

confidence: 99%

Electrical control of the g tensor of the first hole in a silicon MOS quantum dot

et al. 2021

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“…Other dopant and defect sites have emerged in the recent years with the promise of additional functionality. Examples are acceptors 29,49 , systems with high-spin nuclei 50 , and optically active centers 51,52 .…”

Section: Discussionmentioning

confidence: 99%

Novel characterisation of dopant-based qubits

Voisin,

Salfi,

Rahman

et al. 2021

Preprint

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Silicon is a leading qubit platform thanks to the exceptional coherence times that can be achieved and to the available commercial manufacturing platform for integration. Building scalable quantum processing architectures relies on accurate quantum state manipulation, which can only be achieved through a complete understanding of the underlying quantum state properties. This article reviews the electrical methods that have been developed to probe the quantum states encoded in individual and interacting atom qubits in silicon, from the pioneering single electron tunneling spectroscopy framework in nanoscale transistors, to radio frequency reflectometry to probe coherence properties and scanning tunneling microscopy to directly image the wave function at the atomic scale. Together with the development of atomistic simulations of realistic devices, these methods are today applied to other emerging dopant and optically addressable defect states to accelerate the engineering of quantum technologies in silicon.

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“…By virtue of Rashba-like spin-orbit coupling inherent to holes near interfaces, multiqubit electric dipolar coupling greater than the 100-nm-range and all-electrical qubit control can be achieved, while preserving other key qubit properties (e.g., long T 2 * ). 54,55 Furthermore, acceptor holes can couple efficiently via cQED methods using both photons and phonons, for qubit interaction across chipscale distances. 55 Although APAM is not necessarily urgent for investigating acceptor qubits, it could plausibly serve as a means to make systematically reproducible structures, highlighting the important role of APAM for scientific discovery and prototyping.…”

Section: Scaling-up Apam Techniquesmentioning

confidence: 99%

Atomic-precision advanced manufacturing for Si quantum computing

et al. 2021

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A materials synthesis method that we call atomic-precision advanced manufacturing (APAM), which is the only known route to tailor silicon nanoelectronics with full 3D atomic precision, is making an impact as a powerful prototyping tool for quantum computing. Quantum computing schemes using atomic (31P) spin qubits are compelling for future scale-up owing to long dephasing times, one- and two-qubit gates nearing high-fidelity thresholds for fault-tolerant quantum error correction, and emerging routes to manufacturing via proven Si foundry techniques. Multiqubit devices are challenging to fabricate by conventional means owing to tight interqubit pitches forced by short-range spin interactions, and APAM offers the required (Å-scale) precision to systematically investigate solutions. However, applying APAM to fabricate circuitry with increasing numbers of qubits will require significant technique development. Here, we provide a tutorial on APAM techniques and materials and highlight its impacts in quantum computing research. Finally, we describe challenges on the path to multiqubit architectures and opportunities for APAM technique development. Graphic Abstract

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Engineering long spin coherence times of spin–orbit qubits in silicon

Cited by 55 publications

References 38 publications

Electrical control of the g tensor of the first hole in a silicon MOS quantum dot

Electrical control of the g tensor of the first hole in a silicon MOS quantum dot

Novel characterisation of dopant-based qubits

Atomic-precision advanced manufacturing for Si quantum computing

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