Physical systems usually exhibit quantum behavior, such as superpositions and entanglement, only when they are sufficiently decoupled from a lossy environment. Paradoxically, a specially engineered ...interaction with the environment can become a resource for the generation and protection of quantum states. This notion can be generalized to the confinement of a system into a manifold of quantum states, consisting of all coherent superpositions of multiple stable steady states. We have confined the state of a superconducting resonator to the quantum manifold spanned by two coherent states of opposite phases and have observed a Schrödinger cat state spontaneously squeeze out of vacuum before decaying into a classical mixture. This experiment points toward robustly encoding quantum information in multidimensional steady-state manifolds.
As quantum coherence times of superconducting circuits have increased from nanoseconds to hundreds of microseconds, they are currently one of the leading platforms for quantum information processing. ...However, coherence needs to further improve by orders of magnitude to reduce the prohibitive hardware overhead of current error correction schemes. Reaching this goal hinges on reducing the density of broken Cooper pairs, so-called quasiparticles. Here, we show that environmental radioactivity is a significant source of nonequilibrium quasiparticles. Moreover, ionizing radiation introduces time-correlated quasiparticle bursts in resonators on the same chip, further complicating quantum error correction. Operating in a deep-underground lead-shielded cryostat decreases the quasiparticle burst rate by a factor thirty and reduces dissipation up to a factor four, showcasing the importance of radiation abatement in future solid-state quantum hardware.
Transparent thin films of Al-doped ZnO (AZO), Ga-doped ZnO (GZO) and codoped Al + Ga ZnO (AGZO) were deposited on soda-lime glass by RF magnetron sputtering. The influence of aluminum and gallium ...concentrations in zinc oxide (ZnO) films on structural and optical properties of thin films were studied. XRD results shown that the obtained films were with a hexagonal wurtzite structure and preferentially oriented perpendicular to the substrate surface. Atomic force microscopy (AFM) evidenced that the type of doping modifies the microstructure of thin films. Raman spectroscopy was used to study structural properties of complex oxides at a local level. Optical transmission measurements show a small decrease of transparency films when the dopant content increases. The shift of the optical band gap of AZO films with increasing Al and Ga content suggest the enhancement of carrier concentration.
•Effect of Ga doped and (Al + Ga) co-doped on ZnO thin films.•The structural, morphological, vibrational and optical properties.•The morphology was evaluated using AFM method.•The small decrease of Eg for AGZO thin films.
Superconducting high kinetic inductance elements constitute a valuable resource for quantum circuit design and millimeter-wave detection. Granular aluminum (grAl) in the superconducting regime is a ...particularly interesting material since it has already shown a kinetic inductance in the range of nH/□ and its deposition is compatible with conventional Al/AlOx/Al Josephson junction fabrication. We characterize microwave resonators fabricated from grAl with a room temperature resistivity of 4×10^{3} μΩ cm, which is a factor of 3 below the superconductor to insulator transition, showing a kinetic inductance fraction close to unity. The measured internal quality factors are on the order of Q_{i}=10^{5} in the single photon regime, and we demonstrate that nonequilibrium quasiparticles (QPs) constitute the dominant loss mechanism. We extract QP relaxation times in the range of 1 s and we observe QP bursts every ∼20 s. The current level of coherence of grAl resonators makes them attractive for integration in quantum devices, while it also evidences the need to reduce the density of nonequilibrium QPs.
Steps towards current metrology Rastelli, Gianluca; Pop, Ioan M.
Nature physics,
06/2023, Letnik:
19, Številka:
6
Journal Article
Recenzirano
Two superconductors connected by a weak link form a Josephson junction, a nonlinear circuit element at the heart of many quantum devices. Quantized electrical current steps that were predicted ...decades ago have now been observed experimentally.
Granular aluminum (grAl) is a promising high kinetic inductance material for detectors, amplifiers, and qubits. Here we model the grAl structure, consisting of pure aluminum grains separated by thin ...aluminum oxide barriers, as a network of Josephson junctions, and we calculate the dispersion relation and nonlinearity (self-Kerr and cross-Kerr coefficients). To experimentally study the electrodynamics of grAl thin films, we measure microwave resonators with open-boundary conditions and test the theoretical predictions in two limits. For low frequencies, we use standard microwave reflection measurements in a low-loss environment. The measured low-frequency modes are in agreement with our dispersion relation model, and we observe self-Kerr coefficients within an order of magnitude from our calculation starting from the grAl microstructure. Using a high-frequency setup, we measure the plasma frequency of the film around 70 GHz, in agreement with the analytical prediction.
Berberine-containing plants have been traditionally used in different parts of the world for the treatment of inflammatory disorders, skin diseases, wound healing, reducing fevers, affections of ...eyes, treatment of tumors, digestive and respiratory diseases, and microbial pathologies. The physico-chemical properties of berberine contribute to the high diversity of extraction and detection methods. Considering its particularities this review describes various methods mentioned in the literature so far with reference to the most important factors influencing berberine extraction. Further, the common separation and detection methods like thin layer chromatography, high performance liquid chromatography, and mass spectrometry are discussed in order to give a complex overview of the existing methods. Additionally, many clinical and experimental studies suggest that berberine has several pharmacological properties, such as immunomodulatory, antioxidative, cardioprotective, hepatoprotective, and renoprotective effects. This review summarizes the main information about botanical occurrence, traditional uses, extraction methods, and pharmacological effects of berberine and berberine-containing plants.
Aims/hypothesis
Psychological problems are relatively common in people with type 2 diabetes. It is unclear whether exercise training exerts an effect on quality of life, symptoms of depression, ...symptoms of anxiety and emotional well-being in people with type 2 diabetes. The aim of this study was to conduct a systematic review to assess the effects of exercise training on these outcomes in people with type 2 diabetes.
Methods
MEDLINE, PsycINFO, Embase and ClinicalTrials.gov databases were searched. The review included randomised controlled trials (RCTs) of at least 4 weeks’ duration in people with type 2 diabetes that evaluated the effect of exercise training on quality of life, symptoms of depression, symptoms of anxiety and/or emotional well-being compared with usual care.
Results
Of 1,261 retrieved articles, 20 RCTs were included with a total of 1,719 participants. Quality of life was assessed in 16 studies. Between-group comparisons showed no significant results for aerobic training with the exception of one study, and mixed results for resistance and combined training. Symptoms of depression were assessed in four studies. In only one study did the intervention decrease symptoms of depression. Emotional well-being was evaluated in four studies, which also showed conflicting results. Symptoms of anxiety were evaluated in one study, which showed a significant improvement.
Conclusions/interpretation
The effects of exercise training on psychological outcomes in people with type 2 diabetes are conflicting. Therefore, there is a need for further high-quality RCTs in order to gain greater insight into the role of exercise training in people with type 2 diabetes.
We have measured the plasma resonances of an array of Josephson junctions in the regime E(J)>>E(C), up to the ninth harmonic by incorporating it as part of a resonator capacitively coupled to a ...coplanar waveguide. From the characteristics of the resonances, we infer the successful implementation of a superinductance, an electrical element with a nondissipative impedance greater than the resistance quantum R(Q)=h/(2e)(2) is approximately equal to 6.5 kΩ at microwave frequencies. Such an element is crucial for preserving the quantum coherence in circuits exploiting large fluctuations of the superconducting phase. Our results show internal losses less than 20 ppm, self-resonant frequencies greater than 10 GHz, and phase-slip rates less than 1 mHz, enabling direct application of such arrays for quantum information and metrology. Arrays with a loop geometry also demonstrate a new manifestation of flux quantization in a dispersive analog of the Little-Parks effect.
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