Shelving and latching spin readout in atom qubits in silicon

Osika, E. N.; Gorman, Samuel K.; Monir, Serajum; Hsueh, Yu‐Ling; Borscz, Marcus; Geng, Helen; Thorgrimsson, Brandur; Simmons, M. Y.; Rahman, Rajib

doi:10.1103/physrevb.106.075418

Cited by 4 publications

(2 citation statements)

References 49 publications

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“…This work also has clear implications on the need to plan for variability when creating arrays of quantum dots with multiple donors. Indeed, recent work in the field has focused on how to optimize readout for dots with multiple donors . Current semiconductor foundry lithography using extreme ultraviolet excitation achieves 2–3 nm scale patterns.…”

Section: Resultsmentioning

confidence: 99%

“…Indeed, recent work in the field has focused on how to optimize readout for dots with multiple donors. 39 Current semiconductor foundry lithography using extreme ultraviolet excitation achieves 2−3 nm scale patterns. Recent work demonstrates that APAM can also be achieved using UV processes instead of STM, 40 suggesting that meaningful control over doping with relatively low variability may be achievable using foundry processes at the 2−3 nm scale.…”

Section: Size Dependence Of Incorporation In Largermentioning

confidence: 99%

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Quantifying the Variation in the Number of Donors in Quantum Dots Created Using Atomic Precision Advanced Manufacturing

et al. 2023

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Atomic-precision advanced manufacturing enables unique silicon quantum electronics built on quantum dots fabricated from small numbers of phosphorus dopants. The number of dopant atoms comprising a dot plays a central role in determining the behavior of charge and spin confined to the dots and thus overall device performance. In this work, we use both theoretical and experimental techniques to explore the combined impact of lithographic variation and stochastic kinetics on the number of P incorporations in quantum dots made using these techniques and how this variation changes as a function of the size of the dot. Using a kinetic model of PH3 dissociation augmented with novel reaction barriers, we demonstrate that for a 2 × 3 silicon dimer window the probability that no donor incorporates goes to zero, allowing for certainty in the placement of at least one donor. However, this still comes with some uncertainty in the precise number of incorporated donors (either one or two), and this variability may still impact certain applications. We also examine the impact of the size of the initial lithographic window, finding that the incorporation fraction saturates to δ-layer-like coverage as the circumference-to-area ratio decreases. We predict that this incorporation fraction depends strongly on the dosage of the precursor and that the standard deviation of the number of incorporations scales as ∼√n, as would be expected for a sequence of largely independent incorporation events. Finally, we characterize an array of 36 experimentally prepared multidonor 3 × 3 nm lithographic windows with scanning tunneling microscopy, measuring the fidelity of the lithography to the desired array and the final location of PH x fragments within these lithographic windows. We use our kinetic model to examine the expected variability due to the observed lithographic error, predicting a negligible impact on incorporation statistics. We find good agreement between our model and the inferred incorporation locations in these windows from scanning tunneling microscope measurements.

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Section: Resultsmentioning

confidence: 99%

Section: Size Dependence Of Incorporation In Largermentioning

confidence: 99%

Quantifying the Variation in the Number of Donors in Quantum Dots Created Using Atomic Precision Advanced Manufacturing

et al. 2023

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High-fidelity spin readout via the double latching mechanism

Kiyama,

van Hien,

Ludwig

et al. 2024

npj Quantum Inf

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Projective measurement of single-electron spins, or spin readout, is among the most fundamental technologies for spin-based quantum information processing. Implementing spin readout with both high-fidelity and scalability is indispensable for developing fault-tolerant quantum computers in large-scale spin-qubit arrays. To achieve high fidelity, a latching mechanism is useful. However, the fidelity can be decreased by spin relaxation and charge state leakage, and the scalability is currently challenging. Here, we propose and demonstrate a double-latching high-fidelity spin readout scheme, which suppresses errors via an additional latching process. We experimentally show that the double-latching mechanism provides significantly higher fidelity than the conventional latching mechanism and estimate a potential spin readout fidelity of 99.94% using highly spin-dependent tunnel rates. Due to isolation from error-inducing processes, the double-latching mechanism combined with scalable charge readout is expected to be useful for large-scale spin-qubit arrays while maintaining high fidelity.

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Superexchange coupling of donor qubits in silicon

Munia,

Monir,

Osika

et al. 2024

Phys. Rev. Applied

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Atomic engineering in a solid-state material has the potential to functionalize the host with novel phenomena. STM-based lithographic techniques have enabled the placement of individual phosphorus atoms at selective lattice sites of silicon with atomic precision. Here we show that by placing four phosphorus donors spaced 10–15 nm apart from their neighbors in a linear chain, one can realize coherent spin coupling between the end dopants of the chain, analogous to the superexchange interaction in magnetic materials. Since phosphorus atoms are a promising building block of a silicon quantum computer, this enables spin coupling between their bound electrons beyond nearest neighbors, allowing the qubits to be separated by 30–45 nm. The added flexibility in architecture brought about by this long-range coupling not only reduces gate densities but can also reduce correlated noise between qubits from local noise sources that are detrimental to error-correction codes. We base our calculations on a full-configuration-interaction technique in the atomistic tight-binding basis, solving the four-electron problem exactly, over a domain of a million silicon atoms. Our calculations show that superexchange can be tuned electrically through gate voltages where it is less sensitive to charge noise and donor-placement errors. Published by the American Physical Society 2024

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Shelving and latching spin readout in atom qubits in silicon

Cited by 4 publications

References 49 publications

Quantifying the Variation in the Number of Donors in Quantum Dots Created Using Atomic Precision Advanced Manufacturing

Quantifying the Variation in the Number of Donors in Quantum Dots Created Using Atomic Precision Advanced Manufacturing

High-fidelity spin readout via the double latching mechanism

Superexchange coupling of donor qubits in silicon

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