Variability is a problem for the scalability of semiconductor quantum devices. The parameter space is large, and the operating range is small. Our statistical tuning algorithm searches for specific ...electron transport features in gate-defined quantum dot devices with a gate voltage space of up to eight dimensions. Starting from the full range of each gate voltage, our machine learning algorithm can tune each device to optimal performance in a median time of under 70 minutes. This performance surpassed our best human benchmark (although both human and machine performance can be improved). The algorithm is approximately 180 times faster than an automated random search of the parameter space, and is suitable for different material systems and device architectures. Our results yield a quantitative measurement of device variability, from one device to another and after thermal cycling. Our machine learning algorithm can be extended to higher dimensions and other technologies.
Quantum devices with a large number of gate electrodes allow for precise control of device parameters. This capability is hard to fully exploit due to the complex dependence of these parameters on ...applied gate voltages. We experimentally demonstrate an algorithm capable of fine-tuning several device parameters at once. The algorithm acquires a measurement and assigns it a score using a variational auto-encoder. Gate voltage settings are set to optimize this score in real-time in an unsupervised fashion. We report fine-tuning times of a double quantum dot device within approximately 40 min.
Inflammation has been linked to multiple degenerative and acute diseases as well as the aging process. Moreover, mitochondrial alterations play a central role in these processes. Mitochondria have an ...important role in pro-inflammatory signaling; similarly, pro-inflammatory mediators may also alter mitochondrial function. Both of these processes increase mitochondrial oxidative stress, promoting a vicious inflammatory cycle. Additionally, damage-associated molecular patterns derived from mitochondria could contribute to inflammasome formation and caspase-1 activation, while alterations in mitochondrial autophagy may cause inflammation. Strategies aimed at controlling excessive oxidative stress within mitochondria may represent both preventive and therapeutic interventions in inflammation.
Abstract The potential of Si and SiGe-based devices for the scaling of quantum circuits is tainted by device variability. Each device needs to be tuned to operation conditions and each device ...realisation requires a different tuning protocol. We demonstrate that it is possible to automate the tuning of a 4-gate Si FinFET, a 5-gate GeSi nanowire and a 7-gate Ge/SiGe heterostructure double quantum dot device from scratch with the same algorithm. We achieve tuning times of 30, 10, and 92 min, respectively. The algorithm also provides insight into the parameter space landscape for each of these devices, allowing for the characterization of the regions where double quantum dot regimes are found. These results show that overarching solutions for the tuning of quantum devices are enabled by machine learning.
We introduce the “displacemon” electromechanical architecture that comprises a vibrating nanobeam, e.g., a carbon nanotube, flux coupled to a superconducting qubit. This platform can achieve strong ...and even ultrastrong coupling, enabling a variety of quantum protocols. We use this system to describe a protocol for generating and measuring quantum interference between trajectories of a nanomechanical resonator. The scheme uses a sequence of qubit manipulations and measurements to cool the resonator, to apply two effective diffraction gratings, and then to measure the resulting interference pattern. We demonstrate the feasibility of generating a spatially distinct quantum superposition state of motion containing more than106nucleons using a vibrating nanotube acting as a junction in this new superconducting qubit configuration.
On-chip actuation and readout of mechanical motion is key to characterize mechanical resonators and exploit them for new applications. We capacitively couple a silicon nitride membrane to an off ...resonant radio-frequency cavity formed by a lumped element circuit. Despite a low cavity quality factor (Q
≈ 7.4) and off resonant, room temperature operation, we are able to parametrize several mechanical modes and estimate their optomechanical coupling strengths. This enables real-time measurements of the membrane's driven motion and fast characterization without requiring a superconducting cavity, thereby eliminating the need for cryogenic cooling. Finally, we observe optomechanically induced transparency and absorption, crucial for a number of applications including sensitive metrology, ground state cooling of mechanical motion and slowing of light.
In RA, synoviocytes cause increased oxidative stress, leading to mitochondrial alterations that may participate in the pathogenesis of RA. Here we investigated whether mitochondrial dysfunction ...induces inflammatory responses in cultured normal human synoviocytes, a hallmark of RA.
Mitochondrial dysfunction was induced with the inhibitor oligomycin. The effects of mitochondrial dysfunction on cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2) and IL-8 expression; cellular and mitochondrial reactive oxygen species (ROS) production; nuclear factor-κB (NF-κB) activation and p65 translocation were studied. ROS scavengers (N-acetylcysteine and mitoTEMPO) and an NF-κB inhibitor (BAY-117085) were used to investigate the pathways involved. The natural anti-inflammatory antioxidant resveratrol was also tested.
Mitochondrial dysfunction per se significantly stimulated mitochondrial ROS production as well as low-grade expressions of COX-2, PGE2 and IL-8. Interestingly, mitochondrial dysfunction induced by pretreatment of synoviocytes with oligomycin synergized with IL-1β to increase the expression of these inflammatory mediators. The inflammatory effects of mitochondrial damage appeared to be dependent on ROS production and NF-κB activation since the inflammatory response was counteracted by both N-acetylcysteine and mitoTEMPO and it was also reduced by BAY-117085. Antimycin A and paraquat (inhibitors of mitochondrial function) also induced inflammatory responses. Furthermore, resveratrol significantly reduced the inflammatory response by decreasing ROS production and NF-κB activation.
These data suggest that mitochondrial dysfunction could induce an inflammatory response in normal human synoviocytes and sensitize these cells, causing a significant amplification of the inflammatory response induced by IL-1β. Resveratrol may represent a promising strategy in controlling the synovial inflammatory response.
Abstract
Scalable quantum technologies such as quantum computers will require very large numbers of quantum devices to be characterised and tuned. As the number of devices on chip increases, this ...task becomes ever more time-consuming, and will be intractable on a large scale without efficient automation. We present measurements on a quantum dot device performed by a machine learning algorithm in real time. The algorithm selects the most informative measurements to perform next by combining information theory with a probabilistic deep-generative model that can generate full-resolution reconstructions from scattered partial measurements. We demonstrate, for two different current map configurations that the algorithm outperforms standard grid scan techniques, reducing the number of measurements required by up to 4 times and the measurement time by 3.7 times. Our contribution goes beyond the use of machine learning for data search and analysis, and instead demonstrates the use of algorithms to automate measurements. This works lays the foundation for learning-based automated measurement of quantum devices.
Spin-selective tunneling of holes in SiGe nanocrystals contacted by normal-metal leads is reported. The spin selectivity arises from an interplay of the orbital effect of the magnetic field with the ...strong spin-orbit interaction present in the valence band of the semiconductor. We demonstrate both experimentally and theoretically that spin-selective tunneling in semiconductor nanostructures can be achieved without the use of ferromagnetic contacts. The reported effect, which relies on mixing the light and heavy holes, should be observable in a broad class of quantum-dot systems formed in semiconductors with a degenerate valence band.
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