<i>In situ</i>
 Tuning of the Electric-Dipole Strength of a Double-Dot Charge Qubit: Charge-Noise Protection and Ultrastrong Coupling

Scarlino, Pasquale; Ungerer, Jann Hinnerk; Woerkom, David J. van; Mancini, Matteo; Stano, Peter; Müller, Clemens; Landig, Andreas; Koski, Jonne; Reichl, Christian; Wegscheider, Werner; Ihn, Thomas; Ensslin, Klaus; Wallraff, Andreas

doi:10.1103/physrevx.12.031004

Cited by 28 publications

(10 citation statements)

References 46 publications

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“…Motivated by the cavity QED approach, the integration and utilization of hybrid devices composed of semiconductor quantum dots and an on-chip microwave resonator was proposed. A series of works have focused on the engineering challenges for device fabrication, and the demands for improving the qubit-photon coupling strength. − With the application of high-impedance microwave resonators, the coupling strength between a semiconductor qubit and a resonator has been greatly improved, which is one of the issues for quantum computing in semiconductor-based circuit QED. − The observed enhanced Rabi splitting indicates the possibility of two-qubit quantum operations mediated by microwave photons. − However, to date, only up to two semiconductor qubits can simultaneously couple to a resonator. Therefore, the extension of hybrid circuit QED architectures and the exploration of collective effects with multiple qubits are attracting increasing research interest.…”

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confidence: 99%

Collective Microwave Response for Multiple Gate-Defined Double Quantum Dots

Lin

et al. 2023

Nano Lett.

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We fabricate and characterize a hybrid quantum device that consists of five gate-defined double quantum dots (DQDs) and a high-impedance NbTiN transmission resonator. The controllable interactions between DQDs and the resonator are spectroscopically explored by measuring the microwave transmission through the resonator in the detuning parameter space. Utilizing the high tunability of the system parameters and the high cooperativity (C total > 17.6) interaction between the qubit ensemble and the resonator, we tune the charge-photon coupling and observe the collective microwave response changing from linear to nonlinear. Our results present the maximum number of DQDs coupled to a resonator and manifest a potential platform for scaling up qubits and studying collective quantum effects in semiconductor–superconductor hybrid cavity quantum electrodynamics systems.

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confidence: 99%

Collective Microwave Response for Multiple Gate-Defined Double Quantum Dots

Lin

et al. 2023

Nano Lett.

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“…The device layout enables us to reduce the effect of charge fluctuators, which are known to influence and limit device performance. − Typically, charge fluctuators are associated with defect states in the substrate in the vicinity of the active device area. In our case, the SiO 2 between and below the gate electrodes may host a sizable amount of trapping centers. , These defects are tightly linked to noise and charge trapping phenomena, , which can limit the performance of double-quantum dot devices. ,, To assess the impact of charge fluctuators when etching away the SiO 2 beneath the nanotube, we carry out finite-element method simulations using COMSOL (see also Supporting Information, Section 2). Using the geometry of the device in Figure a, the position-dependent electrostatic potential along the nanotube for an electron at the surface of the SiO 2 layer with different etching depths (plain lines) is shown in Figure a.…”

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confidence: 99%

“…The device layout enables us to reduce the effect of charge fluctuators, which are known to influence and limit device performance. 44 − 46 Typically, charge fluctuators are associated with defect states in the substrate in the vicinity of the active device area. In our case, the SiO 2 between and below the gate electrodes may host a sizable amount of trapping centers.…”

mentioning

confidence: 99%

“… 47 , 48 These defects are tightly linked to noise and charge trapping phenomena, 49 , 50 which can limit the performance of double-quantum dot devices. 23 , 45 , 46 To assess the impact of charge fluctuators when etching away the SiO 2 beneath the nanotube, we carry out finite-element method simulations using COMSOL (see also Supporting Information , Section 2). Using the geometry of the device in Figure 2 a, the position-dependent electrostatic potential along the nanotube for an electron at the surface of the SiO 2 layer with different etching depths (plain lines) is shown in Figure 3 a.…”

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confidence: 99%

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Novel Nanotube Multiquantum Dot Devices

et al. 2022

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Addressable quantum states well isolated from the environment are of considerable interest for quantum information science and technology. Carbon nanotubes are an appealing system, since a perfect crystal can be grown without any missing atoms and its cylindrical structure prevents ill-defined atomic arrangement at the surface. Here, we develop a reliable process to fabricate compact multielectrode circuits that can sustain the harsh conditions of the nanotube growth. Nanotubes are suspended over multiple gate electrodes, which are themselves structured over narrow dielectric ridges to reduce the effect of the charge fluctuators of the substrate. We measure high-quality double- and triple-quantum dot charge stability diagrams. Transport measurements through the triple-quantum dot indicate long-range tunneling of single electrons between the left and right quantum dots. This work paves the way to the realization of a new generation of condensed-matter devices in an ultraclean environment, including spin qubits, mechanical qubits, and quantum simulators.

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“…They obtained a maximum value of 60 ns-more than 10 times higher than that of spin qubits formed by single quantum dots. The researchers Credit: P. Scarlino et al [2]…”

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confidence: 99%

Quantum-Dot Qubits Kept Under Control

Wilkinson¹

2022

Physics

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Q uantum dots are tiny semiconductor structures that can serve as qubits, with quantum information stored in the spin or charge states of confined electrons. But the limited coherence time of these qubits greatly restricts their potential applications. Now, Kha Tran at the US Naval Research Laboratory, Washington, DC, and his colleagues, and Pasquale Scarlino at the Swiss Federal Institute of Technology (ETH), Zurich, and his colleagues, have demonstrated ways to increase this coherence time [1, 2].Tran's team considered a spin-based qubit comprising a pair of coupled quantum dots. Previous work had suggested that the coherence time of such a qubit could be extended by operating the system at a particular electrical bias known as the "sweet spot." Tran and his colleagues used a quantum-optics technique called Ramsey interferometry to directly measure the qubit's coherence time at this sweet spot. They obtained a maximum value of 60 ns-more than 10 times higher than that of spin qubits formed by single quantum dots. The researchers Credit: P. Scarlino et al. [2]

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In situ Tuning of the Electric-Dipole Strength of a Double-Dot Charge Qubit: Charge-Noise Protection and Ultrastrong Coupling

Cited by 28 publications

References 46 publications

Collective Microwave Response for Multiple Gate-Defined Double Quantum Dots

Collective Microwave Response for Multiple Gate-Defined Double Quantum Dots

Novel Nanotube Multiquantum Dot Devices

Quantum-Dot Qubits Kept Under Control

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