Quantum phase transitions (QPTs) are usually associated with many-body systems in the thermodynamic limit when their ground states show abrupt changes at zero temperature with variation of a ...parameter in the Hamiltonian. Recently it has been realized that a QPT can also occur in a system composed of only a two-level atom and a single-mode bosonic field, described by the quantum Rabi model (QRM). Here we report an experimental demonstration of a QPT in the QRM using a
Yb
ion in a Paul trap. We measure the spin-up state population and the average phonon number of the ion as two order parameters and observe clear evidence of the phase transition via adiabatic tuning of the coupling between the ion and its spatial motion. An experimental probe of the phase transition in a fundamental quantum optics model without imposing the thermodynamic limit opens up a window for controlled study of QPTs and quantum critical phenomena.
Highly crystalline SnO2 is demonstrated to serve as a stable and robust electron‐transporting layer for high‐performance perovskite solar cells. Benefiting from its high crystallinity, the relatively ...thick SnO2 electron‐transporting layer (≈120 nm) provides a respectable electron‐transporting property to yield a promising power conversion efficiency (PCE)(18.8%) Over 90% of the initial PCE can be retained after 30 d storage in ambient with ≈70% relative humidity.
We experimentally realize a universal set of single-bit and two-bit geometric quantum gates by adiabatically controlling solid-state spins in a diamond defect. Compared with the nonadiabatic ...approach, the adiabatic scheme for geometric quantum computation offers a unique advantage of inherent robustness to parameter variations, which is explicitly demonstrated in our experiment by showing that the single-bit gates remain unchanged when the driving field amplitude varies by a factor of 2 or the detuning fluctuates in a range comparable to the inverse of the gate time. The reported adiabatic control technique and its convenient implementation offer a paradigm for achieving quantum computation through robust geometric quantum gates, which is important for quantum information systems with parameter-fluctuation noise such as those from the inhomogeneous coupling or the spectral diffusion.
Since December 2019, when coronavirus disease 2019 (Covid-19) emerged in Wuhan city and rapidly spread throughout China, data have been needed on the clinical characteristics of the affected ...patients.
We extracted data regarding 1099 patients with laboratory-confirmed Covid-19 from 552 hospitals in 30 provinces, autonomous regions, and municipalities in mainland China through January 29, 2020. The primary composite end point was admission to an intensive care unit (ICU), the use of mechanical ventilation, or death.
The median age of the patients was 47 years; 41.9% of the patients were female. The primary composite end point occurred in 67 patients (6.1%), including 5.0% who were admitted to the ICU, 2.3% who underwent invasive mechanical ventilation, and 1.4% who died. Only 1.9% of the patients had a history of direct contact with wildlife. Among nonresidents of Wuhan, 72.3% had contact with residents of Wuhan, including 31.3% who had visited the city. The most common symptoms were fever (43.8% on admission and 88.7% during hospitalization) and cough (67.8%). Diarrhea was uncommon (3.8%). The median incubation period was 4 days (interquartile range, 2 to 7). On admission, ground-glass opacity was the most common radiologic finding on chest computed tomography (CT) (56.4%). No radiographic or CT abnormality was found in 157 of 877 patients (17.9%) with nonsevere disease and in 5 of 173 patients (2.9%) with severe disease. Lymphocytopenia was present in 83.2% of the patients on admission.
During the first 2 months of the current outbreak, Covid-19 spread rapidly throughout China and caused varying degrees of illness. Patients often presented without fever, and many did not have abnormal radiologic findings. (Funded by the National Health Commission of China and others.).
A novel coronavirus (SCoV) is the etiological agent of severe acute respiratory syndrome (SARS). SCoV-like viruses were isolated from Himalayan palm civets found in a live-animal market in Guangdong, ...China. Evidence of virus infection was also detected in other animals (including a raccoon dog, Nyctereutes procyonoides) and in humans working at the same market. All the animal isolates retain a 29-nucleotide sequence that is not found in most human isolates. The detection of SCoV-like viruses in small, live wild mammals in a retail market indicates a route of interspecies transmission, although the natural reservoir is not known.
Abstract
We report an unusual pressure-induced superconducting state that coexists with an antiferromagnetic ordering of Eu
2+
moments and shows a large upper critical field comparable to the Pauli ...paramagnetic limit in EuTe
2
. In concomitant with the emergence of superconductivity with
T
c
≈ 3–5 K above
P
c
≈ 6 GPa, the antiferromagnetic transition temperature
T
N
(
P
) experiences a quicker rise with the slope increased dramatically from d
T
N
/d
P
= 0.85(14) K/GPa for
P
≤
P
c
to 3.7(2) K/GPa for
P
≥
P
c
. Moreover, the superconducting state can survive in the spin-flop state with a net ferromagnetic component of the Eu
2+
sublattice under moderate magnetic fields
μ
0
H
≥ 2 T. Our findings establish the pressurized EuTe
2
as a rare magnetic superconductor possessing an intimated interplay between magnetism and superconductivity.
Aim: Most guidelines recommend metformin as first‐line therapy in patients with type 2 diabetes. However, the choice of a second‐line drug lacks consistent consensus. We aimed to assess available ...information of antidiabetic drugs added to metformin on the change in glycated haemoglobin A1c (A1C), risk of hypoglycaemia and change in body weight.
Methods: PubMed and Cochrane Central Register of Controlled Trials were searched for randomized controlled trials (RCTs) written in English through December 2011. We analysed direct and indirect comparisons of different treatments using Bayesian network meta‐analysis.
Results: Thirty‐nine RCTs involving 17 860 individuals were included. Glucagon‐like peptide‐1 (GLP‐1) analogues resulted in greater decrease in A1C compared with sulfonylureas, glinides, thiazolidinediones, α‐glucosidase inhibitors and DPP‐4 inhibitors −0.20% (95% CI −0.34 to −0.04%), −0.31% (95% CI −0.61 to −0.02%), −0.20% (95% CI −0.38 to −0.00), −0.36% (95% CI −0.64 to −0.07%), −0.32% (95% CI −0.47 to −0.17%), respectively and was comparable with basal insulin and biphasic insulin. A1C decrease was greater for sulfonylureas compared with DPP‐4 inhibitors −0.12% (−0.23 to −0.03%), and for biphasic insulin compared with glinides (−0.36%; 95% CI −0.82 to −0.11%). Compared with placebo, the risk of hypoglycaemia was increased in the sulfonylureas, glinides, basal insulin and biphasic insulin. Weight increase was seen with sulfonylureas, glinides, thiazolidinediones, basal insulin and biphasic insulin, and weight loss was seen with α‐glucosidase inhibitors and GLP‐1 analogues.
Conclusions: Biphasic insulin, GLP‐1 analogues and basal insulin were ranked the top three drugs in terms of A1C reduction. GLP‐1 analogues did not increase the risk of hypoglycaemia and resulted in a significant decrease in body weight. Most oral antidiabetic drugs had similar effects on A1C, but some agents had a lower risk of hypoglycaemia and body weight gain.
A low‐bandgap (1.33 eV) Sn‐based MA0.5FA0.5Pb0.75Sn0.25I3 perovskite is developed via combined compositional, process, and interfacial engineering. It can deliver a high power conversion efficiency ...(PCE) of 14.19%. Finally, a four‐terminal all‐perovskite tandem solar cell is demonstrated by combining this low‐bandgap cell with a semitransparent MAPbI3 cell to achieve a high efficiency of 19.08%.
PDF
