AlGaAs soliton microcombs at room temperature.

Soliton mode locking in high-Q microcavities provides a way to integrate frequency comb systems. Among material platforms, AlGaAs has one of the largest optical nonlinearity coefficients, and is advantageous for low-pump-threshold comb generation. However, AlGaAs also has a very large thermo-optic effect that destabilizes soliton formation, and femtosecond soliton pulse generation has only been possible at cryogenic temperatures. Here, soliton generation in AlGaAs microresonators at room temperature is reported for the first time, to the best of our knowledge. The destabilizing thermo-optic effect is shown to instead provide stability in the high-repetition-rate soliton regime (corresponding to a large, normalized second-order dispersion parameter D2/κ). Single soliton and soliton crystal generation with sub-milliwatt optical pump power are demonstrated. The generality of this approach is verified in a high-Q silica microtoroid where manual tuning into the soliton regime is demonstrated. Besides the advantages of large optical nonlinearity, these AlGaAs devices are natural candidates for integration with semiconductor pump lasers. Furthermore, the approach should generalize to any high-Q resonator material platform.

Quality Evaluation of Humidified Magnesium Oxide Tablet Formulations with Respect to Disintegration Time Prolongation.

In the present study, we conducted a detailed evaluation of the effects of humidification on the quality of five types of commercial magnesium oxide (MgO) tablet formulations. When near-IR spectroscopy was performed, a peak derived from the first overtone of the stretching vibration of the hydroxyl group was observed at approximately 7200 cm-1 in a humidified MgO tablet formulation. To visually evaluate the effect of this humidification, a mapping image was created using microscopic IR spectroscopy. In the IR spectrum, a peak derived from the stretching vibration of the hydroxyl group appears at approximately 3700 cm-1, so we created a mapping image using the absorbance ratio of 3700 and 3400 cm-1 as an index. In the mapping image of humidified MgO tablet formulations, many areas had a higher absorbance ratio than the dried tablet formulations. From these results, it is qualitatively confirmed that the MgO was changed to magnesium hydroxide (Mg(OH)2) by humidification. Although these results were observed in the four types of MgO tablet formulations, only one type of tablet formulation was less affected by humidification. In addition, although most tablet formulations tended to prolong disintegration time due to humidification, there was almost no effect of humidification on the disintegration time in one type of tablet formulation, which had little change in the above evaluation. Thus, in most commercial MgO tablet formulations, humidification prolongs the disintegration time, and Mg(OH)2 significantly contributes to this factor.

Entanglement and Photon Anti-Bunching in Coupled Non-Degenerate Parametric Oscillators.

We analytically and numerically show that the Hillery-Zubairy's entanglement criterion is satisfied both below and above the threshold of coupled non-degenerate optical parametric oscillators (NOPOs) with strong nonlinear gain saturation and dissipative linear coupling. We investigated two cases: for large pump mode dissipation, below-threshold entanglement is possible only when the parametric interaction has an enough detuning among the signal, idler, and pump photon modes. On the other hand, for a large dissipative coupling, below-threshold entanglement is possible even when there is no detuning in the parametric interaction. In both cases, a non-Gaussian state entanglement criterion is satisfied even at the threshold. Recent progress in nano-photonic devices might make it possible to experimentally demonstrate this phase transition in a coherent XY machine with quantum correlations.

Practical quantum key distribution protocol without monitoring signal disturbance.

Quantum cryptography exploits the fundamental laws of quantum mechanics to provide a secure way to exchange private information. Such an exchange requires a common random bit sequence, called a key, to be shared secretly between the sender and the receiver. The basic idea behind quantum key distribution (QKD) has widely been understood as the property that any attempt to distinguish encoded quantum states causes a disturbance in the signal. As a result, implementation of a QKD protocol involves an estimation of the experimental parameters influenced by the eavesdropper's intervention, which is achieved by randomly sampling the signal. If the estimation of many parameters with high precision is required, the portion of the signal that is sacrificed increases, thus decreasing the efficiency of the protocol. Here we propose a QKD protocol based on an entirely different principle. The sender encodes a bit sequence onto non-orthogonal quantum states and the receiver randomly dictates how a single bit should be calculated from the sequence. The eavesdropper, who is unable to learn the whole of the sequence, cannot guess the bit value correctly. An achievable rate of secure key distribution is calculated by considering complementary choices between quantum measurements of two conjugate observables. We found that a practical implementation using a laser pulse train achieves a key rate comparable to a decoy-state QKD protocol, an often-used technique for lasers. It also has a better tolerance of bit errors and of finite-sized-key effects. We anticipate that this finding will give new insight into how the probabilistic nature of quantum mechanics can be related to secure communication, and will facilitate the simple and efficient use of conventional lasers for QKD.

Determining the Distribution of Active Pharmaceutical Ingredients in Combination Tablets Using Near IR and Low-Frequency Raman Spectroscopy Imaging.

Combination tablets containing multiple active pharmaceutical ingredients (APIs) are expected to improve patient convenience by decreasing the number of tablets to be taken; thus, numerous formulations containing multiple APIs have recently been developed. To allow for dose adjustments based on patient conditions, many tablets have a bisection line to allow equal division of tablets. However, there have been no investigations regarding content uniformity among divided combination tablets. Therefore, in this study, the content uniformity of combination tablets after division was investigated using near IR and low-frequency (LF) Raman spectroscopy imaging as well as the Japanese Pharmacopoeia (JP) content uniformity tests. As model drugs, five tablets of three combination drugs containing 3-(3,4-dihydroxyphenyl)-L-alanine (L-DOPA) and benserazide hydrochloride (BNS) as APIs for treating Parkinson's disease were bisected; the resultant 10 samples were subjected to the JP content uniformity tests. We found that acceptance values of L-DOPA and BNS were 11.0-21.9% and 13.3-17.5%, respectively, with some non-conformity to the maximum allowed acceptance value (15.0%) as per the current JP. Image analyses by near IR showed that L-DOPA, BNS, lactose, and corn starch were uniformly distributed in each tablet; moreover, LF Raman spectroscopy imaging also supported the result that L-DOPA, BNS, and lactose were evenly distributed. Therefore, drug content in the tablets was uniform; thus, careful manipulation was recommended in the tablet bisection. However, the results of bisection line specifications and hardness tests revealed that the ease of division differed depending on the tablets, which warrants attention.

Destabilization of Local Minima in Analog Spin Systems by Correction of Amplitude Heterogeneity.

The relaxation of binary spins to analog values has been the subject of much debate in the field of statistical physics, neural networks, and more recently quantum computing, notably because the benefits of using an analog state for finding lower energy spin configurations are usually offset by the negative impact of the improper mapping of the energy function that results from the relaxation. We show that it is possible to destabilize trapping sets of analog states that correspond to local minima of the binary spin Hamiltonian by extending the phase space to include error signals that correct amplitude inhomogeneity of the analog spin states and controlling the divergence of their velocity. Performance of the proposed analog spin system in finding lower energy states is competitive against state-of-the-art heuristics.

An electrically pumped polariton laser.

Conventional semiconductor laser emission relies on stimulated emission of photons, which sets stringent requirements on the minimum amount of energy necessary for its operation. In comparison, exciton-polaritons in strongly coupled quantum well microcavities can undergo stimulated scattering that promises more energy-efficient generation of coherent light by 'polariton lasers'. Polariton laser operation has been demonstrated in optically pumped semiconductor microcavities at temperatures up to room temperature, and such lasers can outperform their weak-coupling counterparts in that they have a lower threshold density. Even though polariton diodes have been realized, electrically pumped polariton laser operation, which is essential for practical applications, has not been achieved until now. Here we present an electrically pumped polariton laser based on a microcavity containing multiple quantum wells. To prove polariton laser emission unambiguously, we apply a magnetic field and probe the hybrid light-matter nature of the polaritons. Our results represent an important step towards the practical implementation of polaritonic light sources and electrically injected condensates, and can be extended to room-temperature operation using wide-bandgap materials.

Evaluation of the Water Content and Skin Permeability of Active Pharmaceutical Ingredients in Ketoprofen Poultice Formulations Removed from Their Airtight Containers and Left at Room Temperature.

The poultice formulation is a patch containing a large amount of water. It is known that the water contained in the adhesive polymer layer (ADPL) of poultice affects the cooling sensation and skin permeability of the active pharmaceutical ingredient (API). In this study, we evaluated the relationship between the water content in a ketoprofen poultice formulation and the amount of time the poultice was left out at room temperature after removal from the airtight container, as well as the influence of the decreasing water content on the skin permeability of the API. After removing the poultice from the container for 1 h, the mass of the ADPL decreased by approximately 40%. When the near-infrared (NIR) spectrum of the ADPL of poultice was measured, the peaks reflecting the hydroxyl group were attenuated depending on the time left out at room temperature. It is suggested that the changes in the mass and NIR spectrum of the ADPL are caused by the change in the water content. Moreover, when the permeability of API was evaluated on hairless mouse skin, the cumulative skin permeation amount and flux decreased, while the lag time was prolonged as the time left out increased. These results suggest that the skin permeability of the API is impaired by water evaporation and that maintaining the water in the ADPL in poultice is very important from not only the viewpoint of cooling sensation, tackiness and moisturizing but also the skin permeability of the API.

Measurement of the Water Content in Semi-solid Formulations Used to Treat Pressure Ulcers and Evaluation of Their Water Absorption Characteristics.

We investigated the water contents in commercial semi-solid preparations used for pressure ulcer (PU) treatment using near-IR spectroscopy (NIRS) and compared the results with those measured using the Karl Fischer (KF) method. The aim of this study was to determine a standard method and select the appropriate topical preparation with the optimal moisture for PU treatment. The water absorption properties of bases and formulations were evaluated with a time-dependent factor using Transwell as the model membrane. KF and NIRS were applicable as measurement methods of the water content in semi-solid formulations. NIRS was shown to be a useful, simple, nondestructive tool that is more advantageous than the KF method. The water absorption characteristics tested using Transwell revealed that the rate of and capacity for water absorption are determined not only by the absorption ability of the polymer base but also by other factors, such as the osmotic pressure exerted by additives. KF and NIR measurements can be used to choose external skin preparations to control the amount of water in PU treatment.

Quantum-dot spin-photon entanglement via frequency downconversion to telecom wavelength.

Long-distance quantum teleportation and quantum repeater technologies require entanglement between a single matter quantum bit (qubit) and a telecommunications (telecom)-wavelength photonic qubit. Electron spins in III-V semiconductor quantum dots are among the matter qubits that allow for the fastest spin manipulation and photon emission, but entanglement between a single quantum-dot spin qubit and a flying (propagating) photonic qubit has yet to be demonstrated. Moreover, many quantum dots emit single photons at visible to near-infrared wavelengths, where silica fibre losses are so high that long-distance quantum communication protocols become difficult to implement. Here we demonstrate entanglement between an InAs quantum-dot electron spin qubit and a photonic qubit, by frequency downconversion of a spontaneously emitted photon from a singly charged quantum dot to a wavelength of 1,560 nanometres. The use of sub-10-picosecond pulses at a wavelength of 2.2 micrometres in the frequency downconversion process provides the necessary quantum erasure to eliminate which-path information in the photon energy. Together with previously demonstrated indistinguishable single-photon emission at high repetition rates, the present technique advances the III-V semiconductor quantum-dot spin system as a promising platform for long-distance quantum communication.

Molecular State of Active Pharmaceutical Ingredients in Ketoprofen Dermal Patches Characterized by Pharmaceutical Evaluation.

The molecular states of ketoprofen and the interaction between ketoprofen and other pharmaceutical excipients in the matrix layer were examined to determine their effect on the pharmaceutical properties of original and generic ketoprofen dermal patches (generic patches A and B). Molecular states of ketoprofen were evaluated using polarized light microscopy, Raman spectroscopy and powder X-ray diffraction. For the original ketoprofen patch, crystalline components were not observed in the matrix layer. However, crystalline ketoprofen was observed in the two generic ketoprofen patches. Moreover, the ketoprofen exhibited hydrogen bonding with the pharmaceutical excipients or patch materials in the generic products. Skin permeation of ketoprofen from the patches was evaluated using hairless mouse skin. Twelve hours after application, the original patch demonstrated the highest level of cumulative skin permeation of ketoprofen. This was followed by generic patch B while generic patch A showed the lowest level of permeation. Fluxes were calculated from the skin permeation profiles. The original patch was approx. 2.4-times faster compared with generic patch A and approximately 1.9-times faster compared with generic patch B. This investigation suggested that pharmaceutical properties such as skin permeability for these types of products are affected by the precipitation of crystalline ketoprofen in the matrix layer and the interaction of ketoprofen with the pharmaceutical excipients or patch materials.

Stability of Mixed Preparations Consisting of Commercial Moisturizing Creams with an Ointment Base Investigated by Magnetic Resonance Imaging.

A moisturizing cream mixed with a steroid ointment is frequently prescribed to patients suffering from atopic dermatitis. However, there is a concern that the mixing operation causes destabilization. The present study was performed to investigate the stability of such preparations closely using magnetic resonance imaging (MRI). As sample preparations, five commercial moisturizing creams that are popular in Japan were mixed with an ointment base, a white petrolatum, at a volume ratio of 1 : 1. The mixed preparations were stored at 60°C to accelerate the destabilization processes. Subsequently, the phase separations induced by the storage test were monitored using MRI. Using advanced MR technologies including spin-spin relaxation time (T2) mapping and MR spectroscopy, we successfully characterized the phase-separation behavior of the test samples. For most samples, phase separations developed by the bleeding of liquid oil components. From a sample consisting of an oil-in-water-type cream, Urepearl Cream 10%, a distinct phase-separation mode was observed, which was initiated by the aqueous component separating from the bottom part of the sample. The resultant phase separation was the most distinct among the test samples. To investigate the phase separation quantitatively and objectively, we conducted a histogram analysis on the acquired T2 maps. The water-in-oil type creams were found to be much more stable after mixing with ointment base than those of oil-in-water type creams. This finding strongly supported the validity of the mixing operation traditionally conducted in pharmacies.

Analysis of the Stability of External-Application Dermatologic Preparations: Consideration from Rheological Measurements.

The present study examined the stability of mixtures of various combinations of moisturizers, water in oil (w/o)-type or oil in water (o/w)-type cream preparations containing heparinoids, and steroidal ointments or creams (o/w-type) frequently used in children. Centrifugation at room temperature led to separation of mixtures of w/o-type moisturizers and steroidal ointments into three layers. Polarized microscopic observations, near-infrared (NIR) spectroscopy, and dye-based analyses revealed the presence of oily components in the upper and middle layers and water-soluble components in the lower layer. Separation into three layers upon centrifugation was also observed for mixtures of o/w-type moisturizers and steroidal ointments. In contrast, neither the o/w-type moisturizer and steroidal cream nor the w/o-type moisturizer and steroidal cream mixtures separated into layers upon centrifugation. Consideration of the characteristics of each preparation is necessary when mixing external-application dermatologic preparations. Centrifugation at 4°C did not result in layer separation of the w/o-type moisturizer and steroidal ointment mixture, suggesting that cold storage of such mixtures provides superior stability compared with room temperature storage. However, despite no obvious layer separation, the NIR spectra indicated that water movement was induced within the mixture. These results clearly indicate that methods such as NIR spectroscopy are useful for early determinations of the stability of mixed external-application dermatologic preparations.

Binary phase oscillation of two mutually coupled semiconductor lasers.

A two-site Ising model is implemented as an injection-locked laser network consisting of a single master laser and two mutually coupled slave lasers. We observed ferromagnetic and antiferromagnetic orders in the in-phase and out-of-phase couplings between the two slave lasers. Their phase difference is locked to either 0 or π even if the coupling path is continuously modulated. The system automatically selects the oscillation frequency to satisfy the in-phase or out-of-phase coupling condition, when the mutual coupling dominates over the injection-locking by the master laser.

Power-law decay of the spatial correlation function in exciton-polariton condensates.

We create a large exciton-polariton condensate and employ a Michelson interferometer setup to characterize the short- and long-distance behavior of the first order spatial correlation function. Our experimental results show distinct features of both the two-dimensional and nonequilibrium characters of the condensate. We find that the gaussian short-distance decay is followed by a power-law decay at longer distances, as expected for a two-dimensional condensate. The exponent of the power law is measured in the range 0.9-1.2, larger than is possible in equilibrium. We compare the experimental results to a theoretical model to understand the features required to observe a power law and to clarify the influence of external noise on spatial coherence in nonequilibrium phase transitions. Our results indicate that Berezinskii-Kosterlitz-Thouless-like phase order survives in open-dissipative systems.

Analysis of Distribution of Ingredients in Commercially Available Clarithromycin Tablets Using Near-Infrared Chemical Imaging with Principal Component Analysis and Partial Least Squares.

The aim of this study was to evaluate pharmaceuticals using a near-infrared chemical imaging (NIR-CI) technique for visualizing the distribution of ingredients in solid dosage forms of commercially available clarithromycin tablets. The cross section of a tablet was measured using the NIR-CI system for evaluating the distribution of ingredients in the tablet. The chemical images were generated by performing multivariate analysis methods: principal component analysis (PCA) and partial least squares (PLS) with normalized near-infrared (NIR) spectral data. We gained spectral and distributional information related to clarithromycin, cornstarch, and magnesium stearate by using PCA analysis. On the basis of this information, the distribution images of these ingredients were generated using PLS analysis. The results of PCA analysis enabled us to analyze individual components by using PLS even if sufficient information on the products was not available. However, some ingredients such as binder could not be detected using NIR-CI, because their particle sizes were smaller than the pixel size (approximately 25×25×50 µm) and they were present in low concentrations. The combined analysis using both PCA and PLS with NIR-CI was useful to analyze the distribution of ingredients in a commercially available pharmaceutical even when sufficient information on the product is not available.

Magnetic resonance imaging of the phase separation in mixed preparations of moisturizing cream and steroid ointment after centrifugation.

A mixed preparation consisting of a water-in-oil emulsion-type moisturizing cream and a steroid ointment is frequently prescribed for the treatment of atopic dermatitis. We have investigated the compatibility of moisturizing creams and ointments because there are concerns regarding the physical stability of these mixed preparations. The key technology used in this study was magnetic resonance imaging (MRI). A commercial moisturizing cream and white petrolatum or clobetasone butyrate (CLB) ointment samples were mixed in a weight ratio of 1 : 1. A centrifugation test protocol (20000×g for 3 min) was implemented to accelerate the destabilization processes in the samples. After centrifugation, the mixed preparations separated into three distinct layers (upper, middle, and lower), while no phase separation was observed using moisturizing cream alone. The phase separation was monitored using chemical shift selective images of water and oil and quantitative T2 maps. In addition, MR and near-infrared spectroscopy were employed for component analysis of each phase-separated layer. Collectively, it was confirmed that the lower layer contained water, oils, and organic solvent, while the upper and middle layers were composed solely of oils. Furthermore, this study investigated the distribution of CLB in the phase-separated samples and showed that a heterogeneous distribution existed. From our results, it was confirmed that the mixed preparation became unstable because of the incompatibility of the moisturizing cream and ointment.

Studies on uniformity of the active ingredients in acetaminophen suppositories re-solidified after melting under high temperature conditions.

The target of the present pharmaceutical study was the antipyretic analgesic, acetaminophen; its suppository form is usually split when used in pediatric patients. We focused on the active ingredient uniformity in these products, which were re-solidified after melting under high temperature condition. When sections of the cut surfaces of the seven acetaminophen suppository products (SUP-A-G) commercially available in Japan were visualized by polarized microscopy, acetaminophen crystals that were dispersed in the base were identified. The results of the quantitative determination of agent concentration for each cut portion (mg/g) suggested uniform dispersion of these crystals in the base of each product. The agent concentration in each portion of the suppositories that was re-solidified after melting at high temperatures was measured. Segregation of the active ingredient was observed in four products at a temperature of 40°C for 1 h, while active ingredient uniformity was maintained in the other three products (SUP-C, SUP-F and SUP-G). The latter three products also showed high viscosity at 40°C. At 50°C for 4 h, only the uniformity of the active ingredient in SUP-C was maintained. These results suggest that the uniformity of the active ingredient is lost in some acetaminophen suppositories that were re-solidified after melting under high temperature conditions. The degree of loss varies depending on the product.

Ferminoic physics in dipolariton condensates.

An exciton polariton is an extremely light bosonic quasiparticle that is composed of an exciton and a photon. We report on a theoretical study of exciton-polariton condensation in a system with tunnel-coupled quantum wells. Because their excitons can carry an electric dipole moment, these systems have been referred to as dipolariton condensates. We use a fermionic mean-field theory that can address quantum well and other internal exciton degrees of freedom to describe the new physics present in dipolariton condensates. We find that the role of underlying fermonic degrees of freedom is enhanced and predict that metallic condensates can occur at high carrier densities.

Complete quantum control of a single quantum dot spin using ultrafast optical pulses.

A basic requirement for quantum information processing systems is the ability to completely control the state of a single qubit. For qubits based on electron spin, a universal single-qubit gate is realized by a rotation of the spin by any angle about an arbitrary axis. Driven, coherent Rabi oscillations between two spin states can be used to demonstrate control of the rotation angle. Ramsey interference, produced by two coherent spin rotations separated by a variable time delay, demonstrates control over the axis of rotation. Full quantum control of an electron spin in a quantum dot has previously been demonstrated using resonant radio-frequency pulses that require many spin precession periods. However, optical manipulation of the spin allows quantum control on a picosecond or femtosecond timescale, permitting an arbitrary rotation to be completed within one spin precession period. Recent work in optical single-spin control has demonstrated the initialization of a spin state in a quantum dot, as well as the ultrafast manipulation of coherence in a largely unpolarized single-spin state. Here we demonstrate complete coherent control over an initialized electron spin state in a quantum dot using picosecond optical pulses. First we vary the intensity of a single optical pulse to observe over six Rabi oscillations between the two spin states; then we apply two sequential pulses to observe high-contrast Ramsey interference. Such a two-pulse sequence realizes an arbitrary single-qubit gate completed on a picosecond timescale. Along with the spin initialization and final projective measurement of the spin state, these results demonstrate a complete set of all-optical single-qubit operations.