Encoding a magic state with beyond break-even fidelity.

To run large-scale algorithms on a quantum computer, error-correcting codes must be able to perform a fundamental set of operations, called logic gates, while isolating the encoded information from noise1-8. We can complete a universal set of logic gates by producing special resources called magic states9-11. It is therefore important to produce high-fidelity magic states to conduct algorithms while introducing a minimal amount of noise to the computation. Here we propose and implement a scheme to prepare a magic state on a superconducting qubit array using error correction. We find that our scheme produces better magic states than those that can be prepared using the individual qubits of the device. This demonstrates a fundamental principle of fault-tolerant quantum computing12, namely, that we can use error correction to improve the quality of logic gates with noisy qubits. Moreover, we show that the yield of magic states can be increased using adaptive circuits, in which the circuit elements are changed depending on the outcome of mid-circuit measurements. This demonstrates an essential capability needed for many error-correction subroutines. We believe that our prototype will be invaluable in the future as it can reduce the number of physical qubits needed to produce high-fidelity magic states in large-scale quantum-computing architectures.

Conventional vs ultrasonic irrigation - which leads to less post-operative pain?

Data sources Medline, Scopus, Web of Science, Embase, Cochrane Library, ClinicalTrials.gov and OpenGrey databases were systematically searched to find studies comparing post-operative pain experienced following root canal treatment with ultrasonic and conventional irrigation (up to May 2021). Hand searching of selected journals was also performed.Study selection Randomised controlled trials assessing post-operative pain experienced following primary non-surgical root canal treatment using conventional versus ultrasonic irrigation were screened. Exclusion criteria included an unsuitable follow-up period, systemic disease among the participants, severe pain, acute apical abscess diagnoses and fewer than 12 patients per trial arm. English language only studies were included. Two reviewers independently screened the studies and disagreements were resolved by consulting a third reviewer.Data extraction and synthesis Data extracted included tooth type, root type, pre-operative diagnosis, pain recording, time of pain recording, number of patients requiring analgesics and study conclusions. Meta-analyses of different post-operative time periods (6h, 24h, 48h, 72h and 7 days) were performed using a fixed-effects model to obtain a mean difference (with 95% confidence intervals) for post-operative pain. Heterogeneity between studies was evaluated using the I2 statistic. Quality assessment of the included studies was performed according to the Cochrane Collaboration protocol for randomised controlled trials. Publication bias was assessed using a funnel plot and modified via the 'trim-and-fill' method.Results A total of six articles were included in the systematic review, of which four were included in the meta-analysis. Overall risk of bias was deemed to be 'low' with one study presenting an unclear risk with respect to selection bias. Meta-analysis demonstrated that ultrasonic agitation significantly reduced post-operative pain compared to conventional irrigation at 6, 24 and 48 hours (p <0.05) but no significant differences were found at later time points.Conclusions Ultrasonic irrigation may lead to less post-operative pain compared to conventional irrigation techniques; however, the evidence base is limited and further research is needed to support these findings.

Fabrication and characterisation of a silicon-borosilicate glass microfluidic device for synchrotron-based hard X-ray spectroscopy studies.

Some of the most fundamental chemical building blocks of life on Earth are the metal elements. X-ray absorption spectroscopy (XAS) is an element-specific technique that can analyse the local atomic and electronic structure of, for example, the active sites in catalysts and energy materials and allow the metal sites in biological samples to be identified and understood. A microfluidic device capable of withstanding the intense hard X-ray beams of a 4th generation synchrotron and harsh chemical sample conditions is presented in this work. The device is evaluated at the K-edges of iron and bromine and the L 3-edge of lead, in both transmission and fluorescence mode detection and in a wide range of sample concentrations, as low as 0.001 M. The device is fabricated in silicon and glass with plasma etched microchannels defined in the silicon wafer before anodic bonding of the glass wafer into a complete device. The device is supported with a well-designed printed chip holder that made the microfluidic device portable and easy to handle. The chip holder plays a pivotal role in mounting the delicate microfluidic device on the beamline stage. Testing validated that the device was sufficiently robust to contain and flow through harsh acids and toxic samples. There was also no significant radiation damage to the device observed, despite focusing with intense X-ray beams for multiple hours. The quality of X-ray spectra collected is comparable to that from standard methods; hence we present a robust microfluidic device to analyse liquid samples using synchrotron XAS.

High threshold error correction for the surface code.

An algorithm is presented for error correction in the surface code quantum memory. This is shown to correct depolarizing noise up to a threshold error rate of 18.5%, exceeding previous results and coming close to the upper bound of 18.9%. The time complexity of the algorithm is found to be polynomial with error suppression, allowing efficient error correction for codes of realistic sizes.

Bringing order through disorder: localization of errors in topological quantum memories.

Anderson localization emerges in quantum systems when randomized parameters cause the exponential suppression of motion. Here we consider this phenomenon in topological models and establish its usefulness for protecting topologically encoded quantum information. For concreteness we employ the toric code. It is known that in the absence of a magnetic field this can tolerate a finite initial density of anyonic errors, but in the presence of a field anyonic quantum walks are induced and the tolerable density becomes zero. However, if the disorder inherent in the code is taken into account, we demonstrate that the induced localization allows the topological quantum memory to regain a finite critical anyon density and the memory to remain stable for arbitrarily long times. We anticipate that disorder inherent in any physical realization of topological systems will help to strengthen the fault tolerance of quantum memories.

Needle guide in shoulder arthroscopy - a technique.

Distension of joint with fluid is often used to facilitate insertion of arthroscope. This may prove difficult at times in the shoulder joint, as unlike the knee, it is deeply situated, making extravasation of fluid outside the capsule, a common occurrence. This is especially true in very tight joints and is often a problem for beginners. We describe here a very effective and simple technique where a needle is used to distend the shoulder before the insertion of the arthroscope.

Loose Metasul liner causing partial amputation of the neck of the femoral component.

The use of metal-on-metal bearings in total hip arthroplasty is becoming increasingly popular. Several authors have reported excellent medium- and long-term results after the use of the Metasul metal-on-metal articulation (Sulzer Medica, Winterthur, Switzerland). We report a case of a loose Metasul liner eroding the neck of the femoral component resulting in extensive metallosis and weakening of the prosthesis.