This paper focuses on the quantum amplitude estimation algorithm, which is a core subroutine in quantum computation for various applications. The conventional approach for amplitude estimation is to use the phase estimation algorithm, which consists of many controlled amplification operations followed by a quantum Fourier transform. However, the whole procedure is hard to implement with current and near-term quantum computers. In this paper, we propose a quantum amplitude estimation algorithm without the use of expensive controlled operations; the key idea is to utilize the maximum likelihood estimation based on the combined measurement data produced from quantum circuits with different numbers of amplitude amplification operations. Numerical simulations we conducted demonstrate that our algorithm asymptotically achieves nearly the optimal quantum speedup with a reasonable circuit length.Quantum computers are expected to allow us to perform high-speed computations over classical computations for problems in a wide range of scientific and technological fields. Environments in which quantum algorithms can be executed by real quantum devices are currently being provided [1][2][3]. Real quantum devices with several tens of qubits will soon be realized in near future, although those are the socalled noisy intermediate-scale quantum (NISQ) devices that impose several practical limitations on their Y. Suzuki, S. Uno: Equally contributing authors.

Development of sunlight-driven water splitting systems with high efficiency, scalability, and cost-competitiveness is a central issue for mass production of solar hydrogen as a renewable and storable energy carrier. Photocatalyst sheets comprising a particulate hydrogen evolution photocatalyst (HEP) and an oxygen evolution photocatalyst (OEP) embedded in a conductive thin film can realize efficient and scalable solar hydrogen production using Z-scheme water splitting. However, the use of expensive precious metal thin films that also promote reverse reactions is a major obstacle to developing a cost-effective process at ambient pressure. In this study, we present a standalone particulate photocatalyst sheet based on an earth-abundant, relatively inert, and conductive carbon film for efficient Z-scheme water splitting at ambient pressure. A SrTiO:La,Rh/C/BiVO:Mo sheet is shown to achieve unassisted pure-water (pH 6.8) splitting with a solar-to-hydrogen energy conversion efficiency (STH) of 1.2% at 331 K and 10 kPa, while retaining 80% of this efficiency at 91 kPa. The STH value of 1.0% is the highest among Z-scheme pure water splitting operating at ambient pressure. The working mechanism of the photocatalyst sheet is discussed on the basis of band diagram simulation. In addition, the photocatalyst sheet split pure water more efficiently than conventional powder suspension systems and photoelectrochemical parallel cells because H and OH concentration overpotentials and an IR drop between the HEP and OEP were effectively suppressed. The proposed carbon-based photocatalyst sheet, which can be used at ambient pressure, is an important alternative to (photo)electrochemical systems for practical solar hydrogen production.

We explore emergent effects of multidimensionality of the free energy landscape on single-molecule kinetics under constant force. The proposed minimal model reveals the existence of a spectrum of unusual scenarios for the force-dependent lifetime, all of which are shown to occur on a free energy landscape with a single transition state. We present an analytical solution that governs single-molecule responses to a constant force and relates them to microscopic parameters of the system.

Photoelectrochemical water splitting is regarded as ap romising approacht ot he production of hydrogen, and the development of efficient photoelectrodes is one aspect of realizing practical systems.I nt his work, transparent Ta 3 N 5 photoanodes were fabricated on n-type GaN/sapphire substrates to promote O 2 evolution in tandem with aphotocathode, to realize overall water splitting.F ollowing the incorporation of an underlying GaN layer,aphotocurrent of 6.3 mA cm À2 was achieved at 1.23 Vvs. areversible hydrogen electrode.The transparency of Ta 3 N 5 to wavelengths longer than 600 nm allowed incoming solar light to be transmitted to aC uInSe 2 (CIS), whicha bsorbs up to 1100 nm. As tand-alone tandem cell with as erially-connected dual-CIS unit terminated with aP t/Ni electrode was thus constructed for H 2 evolution. This tandem cell exhibited as olar-to-hydrogen energy conversion efficiency greater than 7% at the initial stage of the reaction.Hydrogen generation from water utilizing solar energy is one of the most promising means of producing hydrogen as ac lean, transportable and renewable energy. [1] In addition, overall water splitting using photoelectrochemical (PEC) cells is regarded as ap referable method of converting solar energy to obtain hydrogen. Atypical PEC cell is composed of ap hotoanode and ap hotocathode that are electrically connected to one another and immersed in an aqueous electrolyte solution. [2] Thes olar-to-hydrogen energy conversion efficiency(STH) of aPEC cell is maximized by adjusting the light-receiving area and the common operational potential of both photoelectrodes in order to balance the photocurrent from each. [1a, 2c, 3] AP EC cell having at andem configuration in conjunction with as tacked structure,i ncorporating af ront side transparent photoelectrode along with asecond photoelectrode that responds to the light transmitted through the front side photoelectrode,could potentially allow efficient water splitting. [4] Thed evelopment of transparent photoelectrodes is thus ap rerequisite for constructing such devices.PEC water splitting using Ta 3 N 5 -based photoanodes has been extensively investigated because the band structure of this material is well-suited to water splitting. [5] Liu et al. demonstrated that aT a 3 N 5 -based photoanode can generate ac urrent density of 12.1 mA cm À2 at 1.23 Vv s. ar eversible hydrogen electrode (RHE) under simulated sunlight. [6] This value is close to the theoretical limiting current density under 1s un illumination (12.9 mA cm À2 )e stimated from the band gap of Ta 3 N 5 .O ur own group has previously reported that ap hotoanode based on aT a 3 N 5 thin film prepared on aT a metal substrate can produce 7.5 mA cm À2 at 1.23 Vv s. RHE under simulated sunlight. [7] To date,t here have been few reports of PEC oxygen evolution using transparent Ta 3 N 5 -based photoanodes.H ajibabaei et al. recently reported at ransparent Ta 3 N 5 photoanode prepared on aT a-doped TiO 2 -coated SiO 2 (Ta-TiO 2 / SiO 2 )s ubstrate. [8] This Ta 3 N 5 /Ta-TiO ...

The distribution of a novel neuropeptide, pituitary adenylate cyclase-activating polypeptide (PACAP), was studied in the brain of the rat and man and a variety of other rat tissues using Northern blot hybridization and two radioimmunoassays for PACAP 1-38 and PACAP 1-27. The assay, using PACAP 1-38 as standard and an antibody to PACAP 21-38 and radiolabelled tracer, revealed immunoreactive PACAP in all brain regions examined, with the highest concentrations in the rat being in the hypothalamus, nucleus accumbens and substantia nigra (380 +/- 34, 310 +/- 37 and 346 +/- 30 pmol/g wet tissue, means +/- S.E.M., n = 5 respectively), whilst in man the highest concentrations were found in the pituitary gland (15.8 +/- 4.7 pmol/g). Immunoreactive PACAP 1-38 was also detected in the rat gastrointestinal tract, adrenal gland and testis. The assay using PACAP 1-27 as standard and label and an antibody to PACAP 1-27 detected immunoreactive PACAP only in the rat hypothalamus (12.6 +/- 1.8 pmol/g wet tissue, n = 5). PACAP mRNA of approximately 2.7 kb in size was detectable in all brain regions of both rat and man, and its distribution paralleled that of the immunoreactive peptide. Gel permeation chromatography of different regions of human and rat hypothalamus, and also rat spinal cord and small intestine, showed a broad immunoreactive peak corresponding to PACAP 1-38. Fast protein liquid chromatography (FPLC) resolved this peak into two immunoreactive peaks, the majority eluting in the position of synthetic PACAP 1-38.(ABSTRACT TRUNCATED AT 250 WORDS)

Well-aligned polycrystalline Ta3N5-NRs provide enhanced light harvesting and efficient generation and extraction of charge carriers, leading to completely saturated photocurrent.

The multilayer structure enhances the hydrogen evolution from water under simulated sunlight.

Bismuth vanadate (BiVO4) offers a unique combination of advantages, including being a stable, earth abundant, and visible-light responsive photocatalyst capable of water oxidation. One strategy that is widely employed to enhance the photocatalytic performance of BiVO4 is to improve the carrier transport, which is governed by the interplay between trapping and recombination. To further elucidate the photophysical processes, we investigate the dynamics of often ignored mobile electrons (3435 nm probe) and holes (580 nm probe) using transient absorption spectroscopy. Mobile electrons decay virtually to completion by ∼300 ps, while holes decay in significantly longer periods that far exceed 3000 ps. Furthermore, we use a theoretical model to rationalize the effect of light intensity on the distinctive decay pathways for electrons and holes by trapping and recombination. By employing a simple yet effective formula, we transform the electron decay profile to obtain a hole decay profile that agrees with the experimentally observed transient. A detailed theoretical analysis enables us to determine relevant photophysical parameters such as rate constant values for recombination and trapping, energy levels of traps, and number densities of traps. Results indicate that the electron-trapping process is efficient in BiVO4, and thus direct recombination of electrons with holes is suppressed. Although trapping lowers the electron mobility, it prolongs the lifetimes of holes, which is beneficial for the water-oxidation reaction.