Non-Gaussian Mechanical Motion via Single and Multiphonon Subtraction from a Thermal State.

Quantum optical measurement techniques offer a rich avenue for quantum control of mechanical oscillators via cavity optomechanics. In particular, a powerful yet little explored combination utilizes optical measurements to perform heralded non-Gaussian mechanical state preparation followed by tomography to determine the mechanical phase-space distribution. Here, we experimentally perform heralded single-phonon and multiphonon subtraction via photon counting to a laser-cooled mechanical thermal state with a Brillouin optomechanical system at room temperature and use optical heterodyne detection to measure the s-parametrized Wigner distribution of the non-Gaussian mechanical states generated. The techniques developed here advance the state of the art for optics-based tomography of mechanical states and will be useful for a broad range of applied and fundamental studies that utilize mechanical quantum-state engineering and tomography.

Single-Phonon Addition and Subtraction to a Mechanical Thermal State.

Adding or subtracting a single quantum of excitation to a thermal state of a bosonic system has the counter-intuitive effect of approximately doubling its mean occupation. We perform the first experimental demonstration of this effect outside optics by implementing single-phonon addition and subtraction to a thermal state of a mechanical oscillator via Brillouin optomechanics in an optical whispering-gallery microresonator. Using a detection scheme that combines single-photon counting and optical heterodyne detection, we observe this doubling of the mechanical thermal fluctuations to a high precision. The capabilities of this joint click-dyne detection scheme adds a significant new dimension for optomechanical quantum science and applications.

Multiparameter optimisation of a magneto-optical trap using deep learning.

Machine learning based on artificial neural networks has emerged as an efficient means to develop empirical models of complex systems. Cold atomic ensembles have become commonplace in laboratories around the world, however, many-body interactions give rise to complex dynamics that preclude precise analytic optimisation of the cooling and trapping process. Here, we implement a deep artificial neural network to optimise the magneto-optic cooling and trapping of neutral atomic ensembles. The solution identified by machine learning is radically different to the smoothly varying adiabatic solutions currently used. Despite this, the solutions outperform best known solutions producing higher optical densities.

Topical Therapy with Mesenchymal Stem Cells Following an Acute Experimental Head Injury Has Benefits in Motor-Behavioral Tests for Rodents.

BACKGROUND: The neuroprotective effects of mesenchymal stem cells (MSCs) have been reported in rodent and in preliminary clinical studies. MSCs are usually transplanted to patients by systemic infusion. However, only a few of the infused MSCs are delivered to the brain because of pulmonary trapping and the blood-brain barrier. In this study, MSCs were topically applied to the site of traumatic brain injury (TBI) and the neuroprotective effects were assessed. MATERIALS AND METHODS: TBI was induced in Sprague-Dawley (SD) rats with an electromagnetically controlled cortical impact device after craniotomy was performed between the bregma and lambda, 1 mm lateral to the midline. We applied 1.5 million MSCs, derived from the adipose tissue of transgenic green fluorescent protein (GFP)-SD rats, to the exposed cerebral cortex at the injured site. The MSCs were held in position by a thin layer of fibrin. Neurological function in the test (n = 10) and control (n = 10) animals was evaluated using the rotarod test, the water maze test, and gait analysis at different time points. RESULTS: Within 5 days following topical application, GFP-positive cells were found in the brain parenchyma. These cells co-expressed with markers of Glial fibrillary acidic protein (GFAP), nestin, and NeuN. There was less neuronal death in CA1 and CA3 of the hippocampus in the test animals. Neurological functional recovery was significantly improved. CONCLUSION: Topically applied MSCs can migrate to the injured brain parenchyma and offer neuroprotective effects.

Squeezed light from a diamond-turned monolithic cavity.

For some crystalline materials, a regime can be found where continuous ductile cutting is feasible. Using precision diamond turning, such materials can be cut into complex optical components with high surface quality and form accuracy. In this work we use diamond-turning to machine a monolithic, square-shaped, doubly-resonant LiNbO3 cavity with two flat and two convex facets. When additional mild polishing is implemented, the Q-factor of the resonator is found to be limited only by the material absorption loss. We show how our monolithic square resonator may be operated as an optical parametric oscillator that is evanescently coupled to free-space beams via birefringent prisms. The prism arrangement allows for independent and large tuning of the fundamental and second harmonic coupling rates. We measure 2.6 ± 0.5 dB of vacuum squeezing at 1064 nm using our system. Potential improvements to obtain higher degrees of squeezing are discussed.

Dual-rail optical gradient echo memory.

We introduce a scheme for the parallel storage of frequency separated signals in an optical memory and demonstrate that this dual-rail storage is a suitable memory for high fidelity frequency qubits. The two signals are stored simultaneously in the Zeeman-split Raman absorption lines of a cold atom ensemble using gradient echo memory techniques. Analysis of the split-Zeeman storage shows that the memory can be configured to preserve the relative amplitude and phase of the frequency separated signals. In an experimental demonstration dual-frequency pulses are recalled with 35% efficiency, 82% interference fringe visibility, and 6° phase stability. The fidelity of the frequency-qubit memory is limited by frequency-dependent polarisation rotation and ambient magnetic field fluctuations, our analysis describes how these can be addressed in an alternative configuration.

Nonlinear entanglement and its application to generating cat States.

The Einstein-Podolsky-Rosen (EPR) paradox, which was formulated to argue for the incompleteness of quantum mechanics, has since metamorphosed into a resource for quantum information. The EPR entanglement describes the strength of linear correlations between two objects in terms of a pair of conjugate observables in relation to the Heisenberg uncertainty limit. We propose that entanglement can be extended to include nonlinear correlations. We examine two driven harmonic oscillators that are coupled via third-order nonlinearity can exhibit quadraticlike nonlinear entanglement which, after a projective measurement on one of the oscillators, collapses the other into a cat state of tunable size.

Effect of local injection of mesenchymal stem cells on healing of sutured gastric perforation in an experimental model.

BACKGROUND: Mesenchymal stem cells are proposed to facilitate repair of organ injuries. The aim of this study was to investigate whether local injection of mesenchymal stem cells could accelerate healing of sutured gastric perforations. METHODS: Sutured gastric perforations in rats were treated either with local injection of mesenchymal stem cells (injected MSC group) or by topically spraying with fibrin glue containing mesenchymal stem cells (sprayed MSC group). Controls were treated by local injection of saline or topical spray of fibrin glue without mesenchymal stem cells. Healing of sutured gastric perforations was assessed on days 3, 5 and 7. RESULTS: Local injection of mesenchymal stem cells significantly promoted the healing of gastric perforations, with the highest pneumatic bursting pressure (mean(s.e.m.) 112·3(30·2) mmHg on day 5 versus 71·2(17·4) mmHg in saline controls; P = 0·001), minimal wound adhesions, and lowest incidence of wound dehiscence (3, 6, 5 and 1 animal on day 5 in control, fibrin, sprayed MSC and injected MSC groups respectively; n = 10 per group) and abdominal abscess (2, 2, 1 and no animals respectively on day 5). Histological examination showed that gastric perforations in the injected MSC group displayed reduced inflammation, and increased granulation and re-epithelialization. Sutured gastric perforations in the injected MSC group showed decreased expression of interleukin 6, and increased expression of transforming growth factor ß1 and epithelial proliferating cell nuclear antigen, compared with the other groups. CONCLUSION: Local injection of mesenchymal stem cells was more effective than topical application, and enhanced the healing of sutured gastric perforations by an anti-inflammatory process, enhanced cellular proliferation and earlier onset of granulation. Surgical relevance Abnormal healing of gastric perforation may cause morbidity and increase the risk of death. Adipose tissue-derived mesenchymal stem cells have been found to promote the healing of organ injuries through cellular differentiation and secretion of cytokines that stimulate cellular proliferation and angiogenesis, and suppress inflammation. This study explored the therapeutic potential of such mesenchymal stem cells for promotion of the healing of sutured gastric perforations. Mesenchymal stem cells delivered by local injection significantly enhanced the healing of gastric perforations with reduced severity of wound adhesion, and a decreased incidence of wound dehiscence and abdominal abscess. The increased expression of transforming growth factor ß1, proliferating cell nuclear antigen and reduced level of interleukin 6 provide evidence for enhancement of the healing process. Engrafted mesenchymal stem cells expressed α-smooth muscle actin as a marker of myofibroblasts. This preclinical study indicates that local injection of allogeneic adipose tissue-derived mesenchymal stem cells may have a potential therapeutic role in enhancing the healing of peptic ulcer disease and prevention of ulcer-related complications.

Generalised involuntary limb twitching after ingestion of Mesobuthus martensii Karsch (Quanxie) powder.

Mesobuthus martensii Karsch, commonly known as the Chinese scorpion or Manchurian scorpion, has been used in traditional Chinese medicine as Quanxie to treat chronic pain, tetanus, tremors, convulsion, and paralysis for more than a thousand years. We report a case of poisoning after ingestion of a teaspoon of Quanxie powder. The patient presented with chest pain, dizziness, diaphoresis, generalised involuntary limb twitching, and hypertonia around 15 minutes post-ingestion. The patient recovered uneventfully after supportive management. Intravenous diazepam appeared to be effective in alleviating limb twitching. Failure to accurately measure the dose and to boil before consumption may have contributed to his clinical toxicities.

Configurable unitary transformations and linear logic gates using quantum memories.

We show that a set of optical memories can act as a configurable linear optical network operating on frequency-multiplexed optical states. Our protocol is applicable to any quantum memories that employ off-resonant Raman transitions to store optical information in atomic spins. In addition to the configurability, the protocol also offers favorable scaling with an increasing number of modes where N memories can be configured to implement arbitrary N-mode unitary operations during storage and readout. We demonstrate the versatility of this protocol by showing an example where cascaded memories are used to implement a conditional cz gate.

Scattering-free optical levitation of a cavity mirror.

We demonstrate the feasibility of levitating a small mirror using only radiation pressure. In our scheme, the mirror is supported by a tripod where each leg of the tripod is a Fabry-Perot cavity. The macroscopic state of the mirror is coherently coupled to the supporting cavity modes allowing coherent interrogation and manipulation of the mirror motion. The proposed scheme is an extreme example of the optical spring, where a mechanical oscillator is isolated from the environment and its mechanical frequency and macroscopic state can be manipulated solely through optical fields. We model the stability of the system and find a three-dimensional lattice of trapping points where cavity resonances allow for buildup of optical field sufficient to support the weight of the mirror. Our scheme offers a unique platform for studying quantum and classical optomechanics and can potentially be used for precision gravitational field sensing and quantum state generation.

Squeezed quadrature fluctuations in a gravitational wave detector using squeezed light.

Squeezed states of light are an important tool for optical measurements below the shot noise limit and for optical realizations of quantum information systems. Recently, squeezed vacuum states were deployed to enhance the shot noise limited performance of gravitational wave detectors. In most practical implementations of squeezing enhancement, relative fluctuations between the squeezed quadrature angle and the measured quadrature (sometimes called squeezing angle jitter or phase noise) are one limit to the noise reduction that can be achieved. We present calculations of several effects that lead to quadrature fluctuations, and use these estimates to account for the observed quadrature fluctuations in a LIGO gravitational wave detector. We discuss the implications of this work for quantum enhanced advanced detectors and even more sensitive third generation detectors.

Dettol poisoning and the need for airway intervention.

OBJECTIVES. To (1) characterise the clinical features of Dettol poisoning on a territory-wide basis, (2) assess the need for airway intervention after such poisoning and its time frame after ingestion, and (3) identify predictors for such an intervention. DESIGN. Case series. SETTING. Sixteen accident and emergency departments in Hong Kong. PATIENTS. Patients with Dettol ingestion who presented within 48 hours of ingestion from July 2005 to June 2009, derived from the database of the Hong Kong Poison Information Centre. RESULTS. In all, 213 patient records were identified, of which 36 were excluded based on pre-defined criteria and 177 were analysed. Among the latter, the median age was 32 (range, 2-95) years and the male-to-female ratio was 1:2.7 (48:129). Intentional ingestion constituted the majority (95%) of cases. The most common symptoms were related to the local irritative/corrosive effects on the aero-digestive tract, such as gastro-intestinal upset and localised throat pain. Airway intervention was required in 14 (8%) patients. All interventions were performed within 12 hours of Dettol ingestion and three cases involved re-intubation after extubation. Univariate analysis showed that a Glasgow Coma Scale score of <8, older age, a larger amount ingested, lip swelling, lung crackles, and wheezing were all associated with airway intervention. In the multivariate analysis using forward stepwise logistic regression, only coma (Glasgow Coma Scale score of <8) remained statistically significant. CONCLUSIONS. Delayed airway obstruction (>12 hours after Dettol ingestion) is unlikely. For those who are intubated, careful assessment of airway adequacy before extubation is strongly recommended to avoid extubation failure and subsequent re-intubation. Patients in coma (Glasgow Coma Scale score of <8) should prompt airway intervention.

A scalable, self-analyzing digital locking system for use on quantum optics experiments.

Digital control of optics experiments has many advantages over analog control systems, specifically in terms of the scalability, cost, flexibility, and the integration of system information into one location. We present a digital control system, freely available for download online, specifically designed for quantum optics experiments that allows for automatic and sequential re-locking of optical components. We show how the inbuilt locking analysis tools, including a white-noise network analyzer, can be used to help optimize individual locks, and verify the long term stability of the digital system. Finally, we present an example of the benefits of digital locking for quantum optics by applying the code to a specific experiment used to characterize optical Schrödinger cat states.

High efficiency coherent optical memory with warm rubidium vapour.

By harnessing aspects of quantum mechanics, communication and information processing could be radically transformed. Promising forms of quantum information technology include optical quantum cryptographic systems and computing using photons for quantum logic operations. As with current information processing systems, some form of memory will be required. Quantum repeaters, which are required for long distance quantum key distribution, require quantum optical memory as do deterministic logic gates for optical quantum computing. Here, we present results from a coherent optical memory based on warm rubidium vapour and show 87% efficient recall of light pulses, the highest efficiency measured to date for any coherent optical memory suitable for quantum information applications. We also show storage and recall of up to 20 pulses from our system. These results show that simple warm atomic vapour systems have clear potential as a platform for quantum memory.

Hong Kong's experience on the use of extracorporeal membrane oxygenation for the treatment of influenza A (H1N1).

OBJECTIVE: To report Hong Kong's experience on the use of extracorporeal membrane oxygenation for the treatment of acute respiratory distress syndrome caused by influenza A (H1N1). DESIGN: Multi-centred, retrospective observational study. SETTING: Intensive care units in Hong Kong. PATIENTS: Recipients of extracorporeal membrane oxygenation for confirmed influenza A (H1N1) infection from 1 May 2009 to 28 February 2010. MAIN OUTCOME MEASURE: Hospital mortality. RESULTS: During the study period, 120 patients were mechanically ventilated in intensive care units, among whom seven received veno-venous extracorporeal membrane oxygenation. The median (interquartile range) age of the latter patients was 42 (39-50) years, four had various chronic illnesses and one had a body mass index of greater than 30 kg/m². The median (interquartile range) time from symptom onset to hospital admission was 5 (4-7) days. Corresponding values for the duration of extracorporeal membrane oxygenation, mechanical ventilation, intensive care unit stay, and hospital stay were 6 (6-10), 19 (11-25), 19 (18-30), and 31 (25-55) days, respectively. One patient died (hospital mortality, 14%) and six made full recoveries. All seven patients received oseltamivir; in addition three received intravenous zanamivir, four received convalescent plasma, and one received hyperimmune immunoglobulin. Nosocomial infection was the commonest complication. There was no life- or limb-threatening complication directly attributable to extracorporeal membrane oxygenation. CONCLUSION: In response to the pandemic of influenza A (H1N1), some intensive care units in Hong Kong were able to offer extracorporeal membrane oxygenation to selected cases. In this small series, patient outcomes were similar to those reported in other observational studies, indicating that intensive care units in Hong Kong are capable of successfully introducing this technology. However, the cost-effectiveness and optimal delivery of this strategy remain uncertain.

Precision spectral manipulation of optical pulses using a coherent photon echo memory.

Photon echo schemes are excellent candidates for high efficiency coherent optical memory. They are capable of high-bandwidth multipulse storage, pulse resequencing and have been shown theoretically to be compatible with quantum information applications. One particular photon echo scheme is the gradient echo memory (GEM). In this system, an atomic frequency gradient is induced in the direction of light propagation leading to a Fourier decomposition of the optical spectrum along the length of the storage medium. This Fourier encoding allows precision spectral manipulation of the stored light. In this Letter, we show frequency shifting, spectral compression, spectral splitting, and fine dispersion control of optical pulses using GEM.

Clinical diagnosis of tuberculosis by specialists and non-specialists.

In resource-limited settings, tuberculosis (TB) is often diagnosed by non-physicians using the acid-fast bacilli (AFB) smear only. This study examines the diagnostic accuracy of various clinicians using patient-risk history, radiography and AFB smear. A total of 321 physicians, nurses and medical students evaluated 22 profiles of TB suspects and quantified their clinical suspicion (1-99%). Culture results determined diagnostic accuracy. Overall, high-level physician training may not be required; nurses working on TB, given radiograph readings, were as accurate as TB physicians and more accurate than other physicians and clinicians. By considering clinical findings with smear results, TB specialists were significantly more accurate than smear results alone.