Spin Qubits Confined to a Silicon Nano-Ridge

Klos, J.; Sun, Bin; Beyer, Jacob; Kindel, Sebastian; Hellmich, Lena; Knoch, J.; Schreiber, Lars R.

doi:10.3390/app9183823

Cited by 5 publications

(3 citation statements)

References 57 publications

(81 reference statements)

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“…In this model having a total size of 2600 nm by 400 nm, we randomly distribute uncorrelated singly charged defects at the planar Si/SiO 2 interface having a density of 5 × 10 10 cm −2 . This is a typical defect density for Si/SiO 2 interface extracted from room-temperature C-V measurements [85][86][87].…”

Section: Optimization Of Gate-design For Conveyor Belt Mode Shuttlingmentioning

confidence: 99%

Blueprint of a scalable spin qubit shuttle device for coherent mid-range qubit transfer in disordered Si/SiGe/SiO$_2$

Langrock¹,

Krzywda²,

Focke³

et al. 2022

Preprint

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Silicon spin qubits stand out due to their very long coherence times, compatibility with industrial fabrication, and prospect to integrate classical control electronics. To achieve a truly scalable architecture, a coherent mid-range link between qubit registers has been suggested to solve the signal fan-out problem. Here we present a blueprint of such a ∼ 10 µm long link, called a spin qubit shuttle, which is based on connecting an array of gates into a small number of sets. The number of these gate sets and thus the number of required control signal is independent of the link distance to coherently shuttle the electron qubit. We discuss two different operation modes for the spin qubit shuttle: A qubit conveyor, i.e. a potential minimum that smoothly moves laterally, and a bucket brigade, in which the electron is transported through a series of tunnel-coupled quantum dots by adiabatic passage. We find the former approach more promising considering a realistic Si/SiGe device including potential disorder from the charged defects at the Si/SiO2 layer, as well as typical charge noise. Focusing on the qubit transfer fidelity of the conveyor shuttling mode, motional narrowing, the interplay between orbital and valley excitation and relaxation in presence of g-factors that depend on orbital and valley state of the electron, and effects from spin-hotspots are discussed in detail. We find that a transfer fidelity of 99.9 % is feasible in Si/SiGe at a speed of ∼10 m/s, if the average valley splitting and its inhomogeneity stay within realistic bounds. Operation at low global magnetic field ≈ 20 mT and material engineering towards high valley splitting is favourable to reach high transfer fidelities.

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Section: Optimization Of Gate-design For Conveyor Belt Mode Shuttlingmentioning

confidence: 99%

Blueprint of a scalable spin qubit shuttle device for coherent mid-range qubit transfer in disordered Si/SiGe/SiO$_2$

Langrock¹,

Krzywda²,

Focke³

et al. 2022

Preprint

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“…An ion implantation process was carried out with a dose of 5 × 10 15 atoms/cm 2 , implantation energy of 8 keV, and a 7 • tilt to form the drain and source regions. A combination of dry oxidation and silicon oxide deposition by high-quality plasma-enhanced chemical vapor deposition (PECVD) was used for the passivation of the drain and source feed lines [42]. The passivation was then etched away on the gate area and the drain and source contact area.…”

Section: Sinw-fet Fabricationmentioning

confidence: 99%

Realization of a PEDOT:PSS/Graphene Oxide On-Chip Pseudo-Reference Electrode for Integrated ISFETs

Tintelott

Kremers

Ingebrandt

et al. 2022

Sensors

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A stable reference electrode (RE) plays a crucial role in the performance of an ion-sensitive field-effect transistor (ISFET) for bio/chemical sensing applications. There is a strong demand for the miniaturization of the RE for integrated sensor systems such as lab-on-a-chip (LoC) or point-of-care (PoC) applications. Out of several approaches presented so far to integrate an on-chip electrode, there exist critical limitations such as the effect of analyte composition on the electrode potential and drifts during the measurements. In this paper, we present a micro-scale solid-state pseudo-reference electrode (pRE) based on poly(3,4-ethylene dioxythiophene): poly(styrene sulfonic acid) (PEDOT:PSS) coated with graphene oxide (GO) to deploy with an ion-sensitive field-effect transistor (ISFET)-based sensor platform. The PEDOT:PSS was electropolymerized from its monomer on a micro size gold (Au) electrode and, subsequently, a thin GO layer was deposited on top. The stability of the electrical potential and the cross-sensitivity to the ionic strength of the electrolyte were investigated. The presented pRE exhibits a highly stable open circuit potential (OCP) for up to 10 h with a minimal drift of ~0.65 mV/h and low cross-sensitivity to the ionic strength of the electrolyte. pH measurements were performed using silicon nanowire field-effect transistors (SiNW-FETs), using the developed pRE to ensure good gating performance of electrolyte-gated FETs. The impact of ionic strength was investigated by measuring the transfer characteristic of a SiNW-FET in two electrolytes with different ionic strengths (1 mM and 100 mM) but the same pH. The performance of the PEDOT:PSS/GO electrode is similar to a commercial electrochemical Ag/AgCl reference electrode.

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“…Semiconductor quantum computers require scalable QD qubits to be accurately located in close proximity to each other and also be independently addressable by external electrodes via tunable coupling. To date, advances in Si-based qubit technology have been demonstrated mostly using lithographically-defined approaches including electrostatically-induced QDs and physically-etched QDs based on two-dimensional electron-gas (2DEG) or hole-gas (2DHG) heterostructures [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ] and one-dimensional nanowire structures [ 18 , 19 ]. Among the demonstrated electrostatically-induced QD techniques, overlapping gate architectures [ 8 , 20 ] have offered some flexibility in forming gate-controlled QDs with electrically-tunable coupling between adjacent QDs.…”

Section: Introductionmentioning

confidence: 99%

Germanium Quantum-Dot Array with Self-Aligned Electrodes for Quantum Electronic Devices

et al. 2021

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Semiconductor-based quantum registers require scalable quantum-dots (QDs) to be accurately located in close proximity to and independently addressable by external electrodes. Si-based QD qubits have been realized in various lithographically-defined Si/SiGe heterostructures and validated only for milli-Kelvin temperature operation. QD qubits have recently been explored in germanium (Ge) materials systems that are envisaged to operate at higher temperatures, relax lithographic-fabrication requirements, and scale up to large quantum systems. We report the unique scalability and tunability of Ge spherical-shaped QDs that are controllably located, closely coupled between each another, and self-aligned with control electrodes, using a coordinated combination of lithographic patterning and self-assembled growth. The core experimental design is based on the thermal oxidation of poly-SiGe spacer islands located at each sidewall corner or included-angle location of Si3N4/Si-ridges with specially designed fanout structures. Multiple Ge QDs with good tunability in QD sizes and self-aligned electrodes were controllably achieved. Spherical-shaped Ge QDs are closely coupled to each other via coupling barriers of Si3N4 spacer layers/c-Si that are electrically tunable via self-aligned poly-Si or polycide electrodes. Our ability to place size-tunable spherical Ge QDs at any desired location, therefore, offers a large parameter space within which to design novel quantum electronic devices.

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Spin Qubits Confined to a Silicon Nano-Ridge

Cited by 5 publications

References 57 publications

Blueprint of a scalable spin qubit shuttle device for coherent mid-range qubit transfer in disordered Si/SiGe/SiO$_2$

Blueprint of a scalable spin qubit shuttle device for coherent mid-range qubit transfer in disordered Si/SiGe/SiO$_2$

Realization of a PEDOT:PSS/Graphene Oxide On-Chip Pseudo-Reference Electrode for Integrated ISFETs

Germanium Quantum-Dot Array with Self-Aligned Electrodes for Quantum Electronic Devices

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