Spin Relaxation Benchmarks and Individual Qubit Addressability for Holes in Quantum Dots

Lawrie, William I. L.; Hendrickx, Nico W.; Riggelen, F. van; Russ, Maximilian; Petit, Luca; Sammak, Amir; Scappucci, Giordano; Veldhorst, Menno

doi:10.1021/acs.nanolett.0c02589

Cited by 43 publications

(24 citation statements)

References 41 publications

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“…1(d) we obtain the maximum electric control over the g factor as dg/dV G4 = 8.1 ± 0.2 V −1 (for this specific in-plane magnetic field orientation). The observed dg/dV G for holes is six orders of magnitude larger than dg/dV G for electrons in identical silicon MOS devices [33] and is comparable to dg/dV G observed for holes in other group IV quantum dots [34,51]. Based on the maximum dg/dV G4 we estimate a minimum Rabi frequency of 40 MHz [34,36,52] (see Appendix D); however, a full characterization of the Rabi frequency requires a more detailed study [34].…”

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

confidence: 55%

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: 55%

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

et al. 2021

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“…Precise control over the exchange interactions between adjacent qubits is extremely important for high fidelity quantum operations. While the overlapping gate structure and tight quantum dot definition [19] used here, have proven essential in silicon and in particular SiMOS devices [11], the small effective mass of holes in germanium [36] increases the exchange interaction significantly. While gate voltage pulsing may be used to turn off the exchange, here we operate in a dynamical mode where we program single and multi-qubit gates [3] as required for universal quantum computation and device stability limits the maximal pulsing amplitude.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, advances in strained germanium (Ge/SiGe) have yielded low charge noise and percolation density [17] and high hole mobility [18], indicative of a highly uniform platform. These advantages have advanced the Ge/SiGe platform rapidly over the last few years and led to demonstrations of long spin relaxation times [19], single hole qubits and singlet triplet qubits [16,20] and universal operation on a 2x2 qubit array [3].…”

Section: Introductionmentioning

confidence: 99%

Simultaneous driving of semiconductor spin qubits at the fault-tolerant threshold

Lawrie,

Russ,

van Riggelen

et al. 2021

Preprint

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The promise of quantum information technology hinges on the ability to control large numbers of qubits with highfidelity. Quantum dots define a promising platform due to their compatibility with semiconductor manufacturing. Moreover, high-fidelity operations above 99.9% have been realized with individual qubits [1-3], though their performance has been limited to 98.67% when driving two qubits simultaneously [4]. Here we present single-qubit randomized benchmarking in a two-dimensional array of spin qubits, for one, two and four simultaneously driven qubits. We find that by carefully tuning the qubit parameters, we achieve native gate fidelities of 99.9899(4)%, 99.904(4)% and 99.00(4)% respectively. We also find that cross talk with next-nearest neighbour pairs induces errors that can be imperceptible within the error margin, indicating that cross talk can be highly local. These characterizations of the single-qubit gate quality and the ability to operate simultaneously are crucial aspects for scaling up germanium based quantum information technology.

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“…[ 21–28 ] Besides the electron system, a hole spin qubit in silicon or germanium is also under intensive study recently due to high mobility, suppressed coupling to nuclear noise, fast EDSR, and ease of fabrication. [ 28,107–134 ]…”

Section: Introductionmentioning

confidence: 99%

Dephasing of Exchange‐Coupled Spins in Quantum Dots for Quantum Computing

Huang

2021

Adv Quantum Tech

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A spin qubit in semiconductor quantum dots holds promise for quantum information processing for scalability and long coherence time. An important semiconductor qubit system is a double quantum dot trapping two electrons or holes, whose spin states encode either a singlet–triplet qubit or two single‐spin qubits coupled by exchange interaction. In this article, progress on the spin dephasing of two exchange‐coupled spins in a double quantum dot is reported. First, the schemes of two‐qubit gates and qubit encodings in gate‐defined quantum dots or donor atoms based on the exchange interaction are discussed. Then, the progress on spin dephasing of a singlet–triplet qubit or a two‐qubit gate is reported. The methods of suppressing spin dephasing are further discussed. The understanding of the spin dephasing may provide insights into the realization of high‐fidelity quantum gates for spin‐based quantum computing.

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Spin Relaxation Benchmarks and Individual Qubit Addressability for Holes in Quantum Dots

Cited by 43 publications

References 41 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

Simultaneous driving of semiconductor spin qubits at the fault-tolerant threshold

Dephasing of Exchange‐Coupled Spins in Quantum Dots for Quantum Computing

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