Single-gate accumulation-mode InGaAs quantum dot with a vertically integrated charge sensor

Croke, E. T.; Borselli, Matthew; Gyure, Mark F.; Bui, S.; Milosavljevic, I.; Ross, Richard S.; Schmitz, A.; Hunter, A. T.

doi:10.1063/1.3280368

Cited by 7 publications

(8 citation statements)

References 14 publications

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“…1. This design has been realized in both InGaAs, as previously reported by our group, 7 and now in Si/SiGe. The Si/SiGe heterostructures were grown on strain-relaxed Si 1−x Ge x buffers (0.26 < x < 0.34) and formed twodimensional electron gases supporting mobilities greater than 20 000 cm 2 /Vs at ∼ 5×10 11 cm −2 carrier concentrations.…”

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confidence: 72%

Measurement of valley splitting in high-symmetry Si/SiGe quantum dots

Borselli

Ross

Kiselev

et al. 2011

Applied Physics Letters

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103

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We have demonstrated few-electron quantum dots in Si/SiGe and InGaAs, with occupation number controllable from N = 0. These display a high degree of spatial symmetry and identifiable shell structure. Magnetospectroscopy measurements show that two Si-based devices possess a singlet N =2 ground state at low magnetic field and therefore the two-fold valley degeneracy is lifted. The valley splittings in these two devices were 120 and 270 {\mu}eV, suggesting the presence of atomically sharp interfaces in our heterostructures.Comment: 3 pages, 3 figure

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confidence: 72%

Measurement of valley splitting in high-symmetry Si/SiGe quantum dots

Borselli

Ross

Kiselev

et al. 2011

Applied Physics Letters

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103

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“…Tuning the device to zero charge occupancy is more easily achieved by measuring changes in the transconductance of the QPC corresponding to charge transitions in the double dot. Figure 2 shows AC differential transconductance measurements 16 for all three devices plotted as a function of two depletion gate voltages. All exhibit the ability to achieve the (0, 0) charge configuration, that is zero charge occupancy in both left and right dots.…”

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confidence: 99%

Pauli spin blockade in undoped Si/SiGe two-electron double quantum dots

Borselli¹,

Eng²,

Croke³

et al. 2011

Applied Physics Letters

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108

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We demonstrate double quantum dots fabricated in undoped Si/SiGe heterostructures relying on a double top-gated design. Charge sensing shows that we can reliably deplete these devices to zero charge occupancy. Measurements and simulations confirm that the energetics are determined by the gate-induced electrostatic potentials. Pauli spin blockade has been observed via transport through the double dot in the two electron configuration, a critical step in performing coherent spin manipulations in Si.Comment: 4 pages, 4 figure

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“…10 This approach builds on our previous experience with quantum devices made using single gates in accumulation mode 16,17 and achieves the goal of complete gated control over a set of quantum dots and inter-dot couplings, dominating over the effects of disorder. A nominally undoped epitaxial heterostructure similar to that previously reported by our group 10 produces a tensily-strained Si quantum well on a strain-relaxed Si 0.7 Ge 0.3 buffer.…”

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confidence: 99%

Undoped accumulation-mode Si/SiGe quantum dots

et al. 2015

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We report on a quantum dot device design that combines the low disorder properties of undoped SiGe heterostructure materials with an overlapping gate stack in which each electrostatic gate has a dominant and unique function -control of individual quantum dot occupancies and of lateral tunneling into and between dots. Control of the tunneling rate between a dot and an electron bath is demonstrated over more than nine orders of magnitude and independently confirmed by direct measurement within the bandwidth of our amplifiers. The inter-dot tunnel coupling at the (0, 2) ↔ (1, 1) charge configuration anti-crossing is directly measured to quantify the control of a single inter-dot tunnel barrier gate. A simple exponential dependence is sufficient to describe each of these tunneling processes as a function of the controlling gate voltage.Silicon-based quantum devices hold great promise for realizing spin qubits.1 The ability to isotopically purify silicon has resulted in the demonstration of extremely long spin-coherence times in donor-based silicon devices 1,2 and in recent years a series of results have demonstrated many fundamental properties of electrostatically-defined silicon-based quantum devices. Measurements of T 1 , 3 valley splitting, 4,5 and Pauli blockade 5,6 were made using doped depletion-mode SiGe devices. Improved device performance was achieved by eliminating the intentional dopants in the SiGe heterostructure, a major source of noise and instability, making necessary the use of a global field gate to accumulate electrons. This allowed for demonstrations of high mobility two-dimensional electron gases (2DEGs), 7 Coulomb blockade, 8 valley splitting, 9 Pauli blockade, 10 and T 2 and Rabi measurements. 11The ideal realization of electrostatically-defined quantum dot devices would have independent control of the charge occupancy of each dot and its associated exchange couplings. A promising approach is to utilize an accumulation-based design in which independent localized gates are used to create electron baths, create and control quantum dot occupancy, and modulate tunnel barriers between them. A Si metal-oxide-semiconductor based design has shown great promise along these lines, demonstrating in quick succession charge sensing, 12,13valley splitting, 14 and well-controlled double-dot behavior including spin blockade.15 However better isolation from residual disorder due to gate oxide charges can potentially be achieved using a SiGe heterostructure.In this Letter we report on a double quantum dot device with an integrated dot charge sensor based on a synthesis of the improved gated control of the accumulationmode designs 15 with the lower disorder of field-gated SiGe heterostructure designs.10 This approach builds on our previous experience with quantum devices made using single gates in accumulation mode 16,17 and achieves the goal of complete gated control over a set of quantum dots and inter-dot couplings, dominating over the effects of disorder. A nominally undoped epitaxial heterostructure similar...

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Single-gate accumulation-mode InGaAs quantum dot with a vertically integrated charge sensor

Cited by 7 publications

References 14 publications

Measurement of valley splitting in high-symmetry Si/SiGe quantum dots

Measurement of valley splitting in high-symmetry Si/SiGe quantum dots

Pauli spin blockade in undoped Si/SiGe two-electron double quantum dots

Undoped accumulation-mode Si/SiGe quantum dots

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