Bolometer operating at the threshold for circuit quantum electrodynamics.

Radiation sensors based on the heating effect of absorbed radiation are typically simple to operate and flexible in terms of input frequency, so they are widely used in gas detection1, security2, terahertz imaging3, astrophysical observations4 and medical applications5. Several important applications are currently emerging from quantum technology and especially from electrical circuits that behave quantum mechanically, that is, circuit quantum electrodynamics6. This field has given rise to single-photon microwave detectors7-9 and a quantum computer that is superior to classical supercomputers for certain tasks10. Thermal sensors hold potential for enhancing such devices because they do not add quantum noise and they are smaller, simpler and consume about six orders of magnitude less power than the frequently used travelling-wave parametric amplifiers11. However, despite great progress in the speed12 and noise levels13 of thermal sensors, no bolometer has previously met the threshold for circuit quantum electrodynamics, which lies at a time constant of a few hundred nanoseconds and a simultaneous energy resolution of the order of 10h gigahertz (where h is the Planck constant). Here we experimentally demonstrate a bolometer that operates at this threshold, with a noise-equivalent power of 30 zeptowatts per square-root hertz, comparable to the lowest value reported so far13, at a thermal time constant two orders of magnitude shorter, at 500 nanoseconds. Both of these values are measured directly on the same device, giving an accurate estimation of 30h gigahertz for the calorimetric energy resolution. These improvements stem from the use of a graphene monolayer with extremely low specific heat14 as the active material. The minimum observed time constant of 200 nanoseconds is well below the dephasing times of roughly 100 microseconds reported for superconducting qubits15 and matches the timescales of currently used readout schemes16,17, thus enabling circuit quantum electrodynamics applications for bolometers.

Operation of a silicon quantum processor unit cell above one kelvin.

Quantum computers are expected to outperform conventional computers in several important applications, from molecular simulation to search algorithms, once they can be scaled up to large numbers-typically millions-of quantum bits (qubits)1-3. For most solid-state qubit technologies-for example, those using superconducting circuits or semiconductor spins-scaling poses a considerable challenge because every additional qubit increases the heat generated, whereas the cooling power of dilution refrigerators is severely limited at their operating temperature (less than 100 millikelvin)4-6. Here we demonstrate the operation of a scalable silicon quantum processor unit cell comprising two qubits confined to quantum dots at about 1.5 kelvin. We achieve this by isolating the quantum dots from the electron reservoir, and then initializing and reading the qubits solely via tunnelling of electrons between the two quantum dots7-9. We coherently control the qubits using electrically driven spin resonance10,11 in isotopically enriched silicon12 28Si, attaining single-qubit gate fidelities of 98.6 per cent and a coherence time of 2 microseconds during 'hot' operation, comparable to those of spin qubits in natural silicon at millikelvin temperatures13-16. Furthermore, we show that the unit cell can be operated at magnetic fields as low as 0.1 tesla, corresponding to a qubit control frequency of 3.5 gigahertz, where the qubit energy is well below the thermal energy. The unit cell constitutes the core building block of a full-scale silicon quantum computer and satisfies layout constraints required by error-correction architectures8,17. Our work indicates that a spin-based quantum computer could be operated at increased temperatures in a simple pumped 4He system (which provides cooling power orders of magnitude higher than that of dilution refrigerators), thus potentially enabling the integration of classical control electronics with the qubit array18,19.

Coherent spin control of s-, p-, d- and f-electrons in a silicon quantum dot.

Once the periodic properties of elements were unveiled, chemical behaviour could be understood in terms of the valence of atoms. Ideally, this rationale would extend to quantum dots, and quantum computation could be performed by merely controlling the outer-shell electrons of dot-based qubits. Imperfections in semiconductor materials disrupt this analogy, so real devices seldom display a systematic many-electron arrangement. We demonstrate here an electrostatically confined quantum dot that reveals a well defined shell structure. We observe four shells (31 electrons) with multiplicities given by spin and valley degrees of freedom. Various fillings containing a single valence electron-namely 1, 5, 13 and 25 electrons-are found to be potential qubits. An integrated micromagnet allows us to perform electrically-driven spin resonance (EDSR), leading to faster Rabi rotations and higher fidelity single qubit gates at higher shell states. We investigate the impact of orbital excitations on single qubits as a function of the dot deformation and exploit it for faster qubit control.

Seroma prevention strategies in laparoscopic ventral hernia repair: a systematic review.

BACKGROUND: Laparoscopic ventral hernia repair (LVHR) has been increasing in popularity over the years. Seroma formation is a common complication of LVHR. The aim of this study is to review the current evidence on seroma prevention strategies following LVHR. METHODS: A systematic search of PubMed, Embase (1946-13 February 2019) and Medline (1946-13 February 2019) databases was conducted using terms which include "seroma", "hernia, ventral" and "laparoscopy". All studies are comparative retrospective or prospective human adult studies in peer-reviewed journals describing at least one intra-operative intervention designed to decrease the rate of seroma formation in laparoscopic ventral hernia repair. RESULTS: The database searches identified 3762 citations, and 21 studies were included for final analysis. Five studies compared the different methods of mesh fixation, nine studies compared primary defect closure (PFC) and bridged repair, two studies compared the effect of different types of meshes, two studies looked into the use of electrical cauterization, one study compared single- site laparoscopy with conventional laparoscopy, one study looked into the use of fibrin sealant and one study compared transabdominal preperitoneal placement of mesh with conventional repair. PFC appears to be the most promising with large studies showing a low rate of seroma formation with additional benefits of decreasing wound infection and recurrence rate. Cauterisation of hernia sac and injection of fibrin sealant also show promising results but are mainly derived from small studies. Other strategies did not demonstrate benefit. CONCLUSION: Currently, primary fascial closure appears to be the most promising strategy available to decrease seroma formation after LVHR based on the results of large studies. Other promising strategies that decrease dead space such as cauterisation of the sac and fibrin sealant injection will require further multicentre trials to confirm benefit before an increase in operative time and cost can be justified for their routine use.

Single-spin qubits in isotopically enriched silicon at low magnetic field.

Single-electron spin qubits employ magnetic fields on the order of 1 Tesla or above to enable quantum state readout via spin-dependent-tunnelling. This requires demanding microwave engineering for coherent spin resonance control, which limits the prospects for large scale multi-qubit systems. Alternatively, singlet-triplet readout enables high-fidelity spin-state measurements in much lower magnetic fields, without the need for reservoirs. Here, we demonstrate low-field operation of metal-oxide-silicon quantum dot qubits by combining coherent single-spin control with high-fidelity, single-shot, Pauli-spin-blockade-based ST readout. We discover that the qubits decohere faster at low magnetic fields with [Formula: see text] µs and [Formula: see text] µs at 150 mT. Their coherence is limited by spin flips of residual 29Si nuclei in the isotopically enriched 28Si host material, which occur more frequently at lower fields. Our finding indicates that new trade-offs will be required to ensure the frequency stabilization of spin qubits, and highlights the importance of isotopic enrichment of device substrates for the realization of a scalable silicon-based quantum processor.

Flux-tunable heat sink for quantum electric circuits.

Superconducting microwave circuits show great potential for practical quantum technological applications such as quantum information processing. However, fast and on-demand initialization of the quantum degrees of freedom in these devices remains a challenge. Here, we experimentally implement a tunable heat sink that is potentially suitable for the initialization of superconducting qubits. Our device consists of two coupled resonators. The first resonator has a high quality factor and a fixed frequency whereas the second resonator is designed to have a low quality factor and a tunable resonance frequency. We engineer the low quality factor using an on-chip resistor and the frequency tunability using a superconducting quantum interference device. When the two resonators are in resonance, the photons in the high-quality resonator can be efficiently dissipated. We show that the corresponding loaded quality factor can be tuned from above 105 down to a few thousand at 10 GHz in good quantitative agreement with our theoretical model.

Perfluoroalkyl substances in waters along the Grand Canal, China.

The Grand Canal, also known as the Beijing-Hangzhou Grand Canal, is a UNESCO World Heritage Site and the longest canal in the world. It is an important trunk line of the South-to-North Water Diversion Project in China. The contamination status and spatial distributions of perfluoroalky substances (PFASs) in waters of the Grand Canal were investigated. The total concentrations of PFASs (∑PFASs) range from 7.8 ng/L to 218.0 ng/L, with high ∑PFASs occurring in the southern part of the Grand Canal which is located in a highly urbanized and economically developed region. The dominance of PFOA showed a decreasing trend toward north while shorter chain homologue proportions increased in the northern part of the Canal which mainly traverses underdeveloped and rural areas in Eastern China. Positive correlations were observed between ∑PFASs and the population density as well as GDP per capita. Intersection with large rivers may affect the contamination levels and composition of PFASs in the water of the Grand Canal near the intersection sites.

Detection of Zeptojoule Microwave Pulses Using Electrothermal Feedback in Proximity-Induced Josephson Junctions.

We experimentally investigate and utilize electrothermal feedback in a microwave nanobolometer based on a normal-metal (Au_{x}Pd_{1-x}) nanowire with proximity-induced superconductivity. The feedback couples the temperature and the electrical degrees of freedom in the nanowire, which both absorbs the incoming microwave radiation, and transduces the temperature change into a radio-frequency electrical signal. We tune the feedback in situ and access both positive and negative feedback regimes with rich nonlinear dynamics. In particular, strong positive feedback leads to the emergence of two metastable electron temperature states in the millikelvin range. We use these states for efficient threshold detection of coherent 8.4 GHz microwave pulses containing approximately 200 photons on average, corresponding to 1.1×10^{-21} J≈7.0 meV of energy.

'Start to finish trans-institutional transdisciplinary care': a novel approach improves colorectal surgical results in frail elderly patients.

AIM: The frail elderly surgical patient is at increased risk of morbidity after major surgery. A transdisciplinary Geriatric Surgery Service (GSS) has been shown to produce consistently positive results in our institution. A trans-institutional transdisciplinary Start to Finish (STF) programme was initiated incorporating seamless prehabilitation and rehabilitation to enhance the outcome further. METHOD: Patients who underwent major colorectal resection in Khoo Teck Puat Hospital and were managed under the GSS from January 2007 to December 2014 were included in this prospective study. The STF programme was initiated from January 2012. The surgical outcome of patients managed under the GSS before the initiation of STF was compared with that after its implementation. RESULTS: There were 57 patients after the initiation of the STF programme compared with 60 patients managed before STF. There were 26.4% and 25% of frail patients in the STF group compared with the non-STF group (P = 0.874). The mean length of hospital stay was significantly shorter in the STF group (8.4 days vs 11.0 days, P = 0.029). Functional recovery in patients available for follow-up at 6 weeks showed 100% (46/46) recovery in the elective STF group who received prehabilitation and 95.7% (45/47) in the elective non-STF group who did not (P = 0.157). There were no significant differences in a Clavien-Dindo complication score of Grade 3 or more and 30-day mortality between the two groups. CONCLUSION: Through a trans-institutional transdisciplinary approach, we managed to achieve a significantly shorter hospital stay in frail patients having colorectal surgery. All elective patients who received prehabilitation achieved full functional recovery.

Latitudinal distributions of activities in atmospheric aerosols, deposition fluxes, and soil inventories of 7Be in the East Asian monsoon zone.

Activities of atmospheric aerosols, bulk deposition fluxes, and undisturbed soil inventories of (7)Be were investigated in China's East Asian monsoon zone at various latitudes ranging from 23.8°N to 43.5°N. The annual latitudinal distributions of (7)Be concentrations in aerosols follow a distribution pattern which looks similar to a normal distribution with the maxima occurring in the mid-latitude region. Simultaneous measurements of (7)Be at various latitudes suggest that atmospheric circulation may play an important role in the latitudinal distributions of (7)Be in surface air. Latitude and wet precipitation are the main factors controlling the bulk (7)Be depositional fluxes. Significant seasonal variations in (7)Be depositional fluxes in Beijing, a mid-latitude city, were observed with the highest flux in summer and the lowest in winter, whereas less seasonality were found in the high- and the low-latitude cities. The highest (7)Be inventory in undisturbed soils in summer also occurred at a mid-latitudinal area in the East Asian monsoon zone. Precipitation is the main factor controlling the (7)Be soil inventory in Qingdao with the highest values occurring in autumn followed by summer.

Randomized single-blind clinical trial of intradermal methylene blue on pain reduction after open diathermy haemorrhoidectomy.

BACKGROUND: Open haemorrhoidectomy has been associated with considerable postoperative pain and discomfort. Perianal intradermal injection of methylene blue has been shown to ablate perianal nerve endings and may bring about temporary pain relief after haemorrhoidectomy. We hypothesized that the administration of intradermal methylene blue would reduce postoperative pain during the initial period after surgery. METHOD: A randomized, prospective, single-blind placebo-controlled trial was conducted. Patients were randomized to intradermal injection at haemorrhoidectomy of either 4 ml 1% methylene blue and 16 ml 0.5% marcaine or of 16 ml 0.5% marcaine and 4 ml saline prior to surgical dissection. Patients were asked to fill in a pain diary with a visual analogue scale. The primary outcome measure was pain score and analgesic use. Secondary outcomes were complications. RESULTS: There were 37 patients in the methylene blue arm and 30 patients in the placebo arm. There were no statistically significant differences in the sex, type of haemorrhoid, number of haemorrhoids excised, duration of surgery or hospital stay. The mean pain scores were significantly lower and the use of paracetamol was also significantly less in the methylene blue group during the first three postoperative days. The risk ratio of acute urinary retention occurring when methylene blue was not used was 2.320 (95% CI 1.754-3.067). Other complication rates were not significantly different. CONCLUSION: Perianal intradermal injection of methylene blue was useful in reducing the initial postoperative pain of open haemorrhoidectomy.

Tunable electromagnetic environment for superconducting quantum bits.

We introduce a setup which realises a tunable engineered environment for experiments in circuit quantum electrodynamics. We illustrate this concept with the specific example of a quantum bit, qubit, in a high-quality-factor cavity which is capacitively coupled to another cavity including a resistor. The temperature of the resistor, which acts as the dissipative environment, can be controlled in a well defined manner in order to provide a hot or cold environment for the qubit, as desired. Furthermore, introducing superconducting quantum interference devices (SQUIDs) into the cavity containing the resistor, provides control of the coupling strength between this artificial environment and the qubit. We demonstrate that our scheme allows us to couple strongly to the environment enabling rapid initialization of the system, and by subsequent tuning of the magnetic flux of the SQUIDs we may greatly reduce the resistor-qubit coupling, allowing the qubit to evolve unhindered.

Nanoscale broadband transmission lines for spin qubit control.

The intense interest in spin-based quantum information processing has caused an increasing overlap between the two traditionally distinct disciplines of magnetic resonance and nanotechnology. In this work we discuss rigorous design guidelines to integrate microwave circuits with charge-sensitive nanostructures, and describe how to simulate such structures accurately and efficiently. We present a new design for an on-chip, broadband, nanoscale microwave line that optimizes the magnetic field used to drive a spin-based quantum bit (or qubit) while minimizing the disturbance to a nearby charge sensor. This new structure was successfully employed in a single-spin qubit experiment, and shows that the simulations accurately predict the magnetic field values even at frequencies as high as 30 GHz.

Pneumothorax following endoscopic submucosal dissection of a rectal tumor.

Endoscopic submucosal dissection is a useful alternative to endoscopic mucosal resection and surgery for en bloc resection of colorectal tumors. However, the technique is considered to be difficult, and potential complications include perforation and postoperative bleeding. In this case report, we present a case of a 63-year-old woman who developed pneumothorax after endoscopic submucosal dissection of a rectal tumor.

Reproducibility and diagnostic value of E100 event recorder for patients with complains on heart arrhythmias and no changes on multiple routine ECGs and 24-hour holter monitoring.

Aim of the study was to assess reproducibility and diagnostic value of E100 event recorder for patients with complains on heart arrhythmias and no abnormalities on multiple routine ECGs and/or 24-hour Holter ECG monitoring and the second one, an assessment of adherence and attitude of patients to the E100 event recorder, dependent on the results of self- assessment questionnaires. 24 patients with complains on heart arrhythmias were included in the study. All the patients were provided with the REKA E100 event monitors for 5 ± 2 days and self-assessment questionnaires to assess level of adherence and attitude of patients to the E100 event recorder. E100 event recorders revealed junctional rhythm (n=2), AV nodal reentrant tachycardia (n=2), extrasystolic arrhythmias (n=10), atrial fibrillation (n=2), WPW syndrome (n=4), ventricular tachycardia (n=1), sinus tachycardia (n=7) and complete AV block (n=1). Majority of patients consider device as easy to use, comfortable and safe. In comparison with multiple routine ECGs and 24-hour Holter ECG monitoring, E100 event recorders showed higher reproducibility and efficacy for detecting and interpreting heart arrhythmias.

Proximal bowel necrosis after high ligation of the inferior mesenteric artery in colorectal surgery.

BACKGROUND AND AIMS: High ligation of the inferior mesenteric artery may jeopardize blood supply to the proximal bowel. We undertook this study to review the clinical features and outcomes of patients who developed proximal bowel necrosis after high ligation of the inferior mesenteric artery, and to assess the incidence and the risk factors for this complication. MATERIALS AND METHODS: A retrospective analysis of patients undergoing high or low ligation for sigmoid colon and rectal cancer with a primary anastomosis between April 2004 and March 2009 was performed. Patient and tumor characteristics and the incidence of bowel necrosis were reviewed. RESULTS: Four hundred and nine patients were included to the analysis. Six out of 302 patients (2.0%) with high ligation developed proximal bowel necrosis, while the remaining 107 patients with low ligation did not suffer from this complication. All patients who developed proximal bowel necrosis underwent secondary surgery with resection of necrotic bowel. The pathological examination of the resected specimen revealed mucosal to transmural ischemic necrosis without the evidence of vascular thrombosis or embolic occlusion. Univariate analysis revealed that advanced age, cerebrovascular disease, and hypertension were significantly associated with proximal bowel necrosis. Multivariate analysis demonstrated that cerebrovascular disease was an independent predictor of this complication. Of these six patients, two died from associated complications. CONCLUSIONS: Proximal bowel necrosis after high ligation is potentially fatal, and this report provides a warning in clinical settings where high ligation is indicated. Further studies are warranted to evaluate its distinct relationship with high ligation and to clarify whether low ligation would be a safeguard.

Prospective study to validate HpOne in the diagnosis of Helicobacter pylori infection.

INTRODUCTION: The HpOne test is a new five-minute rapid urease test developed for the rapid detection of Helicobacter pylori infection during gastroscopy. However, evidence in the literature supporting its use clinically is scarce. The most commonly used rapid urease test remains the Campylobacter-like organism (CLO) test, which generates accurate readings only after 24 hours. The aim of this study was to evaluate the efficacy of the HpOne test in our local population. METHODS: From August 2007 to May 2008, consecutive patients undergoing gastroscopy for various indications were recruited into this prospective study. Patients who were pregnant, lactating, on proton pump inhibitors, antibiotics, immunosuppressants or had previous gastric surgery were excluded. During gastroscopy, six gastric mucosal biopsies were taken; three from the body and three from the antrum. One body and one antral biopsy were used for each of the HpOne test, CLO test and histology. Results of the HpOne and CLO tests were then compared against the gold standard of histology. RESULTS: Of the 149 patients recruited, 82 (55 percent) were men and 67 (45 percent) were women. The prevalence of Helicobacter pylori infection was 38.9 percent (n is 58). The sensitivity and specificity of the HpOne test were 65.5 percent and 85.7 percent, respectively, while those for the CLO test were 63.8 percent and 84.6 percent, respectively. CONCLUSION: The HpOne test is as efficacious as the CLO test, with the added advantage of yielding results faster. It is thus a superior alternative and should be considered for clinical use.