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“Thick electrode using high voltage cathode” can be considered, since this research focuses on high voltage cathode materials.

Entangled qudits, the high-dimensional entangled states, play an important role in the study of quantum information. How to prepare entangled qudits in an efficient and easy-to-operate manner is still a challenge in quantum technology. Here, we demonstrate a method to engineer frequency entangled qudits in a spontaneous parametric downconversion process. The proposal employs an angle-dependent phase-matching condition in a nonlinear crystal, which forms a classical-quantum mapping between the spatial (pump) and spectral (biphotons) degrees of freedom. In particular, the pump profile is separated into several bins in the spatial domain, and thus shapes the down-converted biphotons into discrete frequency modes in the joint spectral space. Our approach provides a feasible and efficient method to prepare a high-dimensional frequency entangled state. As an experimental demonstration, we generate a three-dimensional entangled state by using a homemade variable slit mask., 9 pages, 9 figures

Transitioning toward more sustainable materials and manufacturing methods will be critical to continue supporting the rapidly expanding market for lithium-ion batteries. Meanwhile, energy storage applications are demanding higher power and energy densities than ever before, with aggressive performance targets like fast charging and greatly extended operating ranges and durations. Due to its high operating voltage and cobalt-free chemistry, the spinel-type LiNi0.5Mn1.5O4 (LNMO) cathode material has attracted great interest as one of the few next-generation candidates capable of addressing this combination of challenges. However, severe capacity degradation and poor interphase stability have thus far impeded the practical application of LNMO. In this study, by leveraging a dry electrode coating process, we demonstrate LNMO electrodes with stable full cell operation (up to 68% after 1000 cycles) and ultra-high loading (up to 9.5 mAh/cm2 in half cells). This excellent cycling stability is ascribed to a stable cathode-electrolyte interphase, a highly distributed and interconnected electronic percolation network, and robust mechanical properties. High-quality images collected using plasma focused ion beam scanning electron microscopy (PFIB-SEM) provide additional insight into this behavior, with a complementary 2-D model illustrating how the electronic percolation network in the dry-coated electrodes more efficiently supports homogeneous electrochemical reaction pathways. These results strongly motivate that LNMO as a high voltage cobalt-free cathode chemistry combined with an energy-efficient dry electrode coating process opens the possibility for sustainable electrode manufacturing of cost-effective and high-energy-density cathode materials.

Background Ensitrelvir is a novel oral SARS-CoV-2 3C-like protease inhibitor, and under late clinical development stage for COVID-19 diseases. Ensitrelvir exhibited an inhibition potency for organic cation transporter 1 (OCT1) and multidrug and toxin extrusion protein 1 (MATE1) in in vitro study and clinical drug-drug interaction (DDI) study is required judging from DDI guidance. Metformin is widely used for treatment of diabetes, and is a sensitive substrate for OCT1 and MATE1. We evaluated the effect of ensitrelvir on the pharmacokinetics (PK) of metformin with physiologically-based pharmacokinetic (PBPK) modeling and simulation and clinical DDI study. Methods The PBPK model of ensitrelvir was developed based on the physicochemical parameters, in vitro transporter inhibition parameters, and estimated PK parameters for human. DDI simulations between ensitrelvir and metformin were performed. Simcyp PBPK Simulator (Version 20, Certara UK Limited, UK) was used to develop PBPK model and simulate the DDIs. The in vitro 50% inhibitory concentration (IC50) values of each transporter were used as inhibition constant (Ki) for DDI simulations. Based on the PBPK analysis, the clinical DDI study planed. Results PBPK analysis: As the result of DDI simulation, ensitrelvir increased the area under the curve (AUC) of metformin by 12%. The result suggests that in vivo DDI potency of ensitrelvir via inhibition of OCT1 or MATE1 would be low at a single dose of ensitrelvir 1000 mg. Clinical DDI study: The plasma concentration-time profile of metformin and ensitrelvir were monitored after 96 hours from a single dose of metformin with or without ensitrelvir. Ensitrelvir does not have effect on the PK of metformin (a geometric mean of AUC ratio was 1.02, Japanese healthy subjects, N=14), suggesting no MATE1 and OCT1 inhibition by ensitrelvir at a clinical dose. The PBPK analysis could well predict the clinical DDI study result. Conclusion The results of PBPK analysis and the clinical DDI study suggest that no OCT1 and MATE1 inhibition by ensitrelvir is in the clinical dose. Therefore, ensitrelvir does not have a clinically meaningful effect on the pharmacokinetic profile of OCT1 and/or MATE1 substrates including metformin. Disclosures Kana Horiuchi, Shionogi & Co., Ltd.: employee Hiroki Koshimichi, n/a, Shionogi & Co., Ltd.: employee Takanobu Matsuzaki, Ph.D., Shionogi & Co., Ltd.: Employee Ryosuke Shimizu, Shionogi & Co., Ltd.: employee Shinpei Yoshida, Ph.D., Shionogi & Co., Ltd.: employee Ryuji Kubota, Ph.D., Shionogi & Co., Ltd.: employee|Shionogi & Co., Ltd.: employee Shingo Sakamoto, n/a, Shionogi & Co., Ltd.: employee.

The polarizable continuum model (PCM) has been one of the most widely used approaches to take into account the solvation effect in quantum chemical calculations. In this paper, we performed a series of benchmark calculations to assess the accuracy of the PCM scheme combined with the second-order complete-active-space perturbation theory (CASPT2) for molecular systems in polar solvents. For solute molecules with extensive conjugated π orbitals, exemplified by elongated conjugated arylcarbenes, we have incorporated the ab initio density matrix renormalization group algorithm into the PCM-CASPT2 method. In the previous work, we presented a combination of the DMRG-CASPT2 method with the reference interaction site model (RISM) theory for describing the solvation effect using the radial distribution function and compared its performance to the widely used density-functional approaches (PCM-TD-DFT). The work here allows us to further show a more thorough assessment of the RISM model compared to the PCM with an equal level of the wave function treatment, the (DMRG-)CASPT2 theory, toward a high-accuracy electronic structure calculations for solvated chemical systems. With the exception that the PCM models are not capable of properly describing the hydrogen bondings, accuracy of the PCM-CASPT2 model is in most cases quite comparable to the RISM counterpart.

Ensitrelvir is a novel selective inhibitor of the 3C-like protease of SARS-CoV-2, which is essential for viral replication. This phase 1 study of ensitrelvir assessed its safety, tolerability, and pharmacokinetics of single (part 1, n = 50) and multiple (part 2, n = 33) ascending oral doses.

Lithium phosphorus oxynitride (LiPON) is a well-known amorphous thin film solid electrolyte that has been extensively studied in the last three decades. Despite the promises to enable Li metal anode and various cathode materials, the presence of rigid substrate and LiPON’s unique amorphous, air-sensitive characteristics set limitations to comprehensively understand its intrinsic properties for next-stage advancement and applications. This work demonstrates a different methodology to synthesize LiPON in a freestanding form that removes the substrate. The freestanding LiPON (FS-LiPON) exhibits remarkable flexibility, with controllable film thickness and large-scale production compatibility. Benefited from the freestanding form, solid-state nuclear magnetic resonance (ss-NMR) and differential scanning calorimetry (DSC) are able to attain high S/N ratio to determine the local bonding structures and glass transition temperature of LiPON. In the presence of interfacial stress and a seeding layer, FS-LiPON demonstrates a uniform and fully dense Li metal deposition without the aid of external pressure. Such a FS-LiPON film offers new opportunities for fundamental study of LiPON material and associated interfaces, and provide perspectives for interface engineering in bulk solid-state battery.

ObjectiveAlthough mindfulness and self-compassion programs have been applied in clinical settings, no studies have reported their benefits for atopic dermatitis (AD). The aim of the study was to evaluate the feasibility and acceptability of an online group format of 8 weekly 90-minute sessions of a mindfulness and self-compassion program for adults with AD.ResultsIn this single-arm, open label pre-post comparison study design, 15 adults (10 women; mean age, 38.3 ± 8.98 years) completed the intervention and assessment. The primary outcome was disease-specific quality of life (QOL) (Dermatology Life Quality Index and Skindex-16) at the 20-week follow-up. The secondary outcomes were other self-reported questionnaires, and descriptive feedback of the program. Assessments were conducted at baseline, mid-treatment, post-intervention, and at follow-up. Overall, there were no significant improvements. However, of the four participants whose QOL was largely impacted due to AD, the scores improved significantly, with minimal clinically important difference or greater change. All participants were satisfied with the program. This program could benefit adults with AD by improving QOL. Randomized controlled trials are warranted to elucidate the efficacy of the program. This study has been registered at the UMIN Clinical Trials Registry (ID: UMIN000030484).

Lithium phosphorus oxynitride (LiPON) is an amorphous solid-state lithium ion conductor displaying exemplary cyclability against lithium metal anodes. There is no definitive explanation for this stability due to the limited understanding of the structure of LiPON. We provide a structural model of RF-sputtered LiPON via experimental and computational spectroscopic methods. Information about the short-range structure results from 1D and 2D solid-state nuclear magnetic resonance experiments investigating chemical shift anisotropy and dipolar interactions. These results are compared with first principles chemical shielding calculations of Li-P-O/N crystals and ab initio molecular dynamics-generated amorphous LiPON models to unequivocally identify the glassy structure as primarily isolated phosphate monomers with N incorporated in both apical and as bridging sites in phosphate dimers. Structural results suggest LiPON's stability is a result of its glassy character. Free-standing LiPON films are produced that exhibit a high degree of flexibility highlighting the unique mechanical properties of glassy materials.

Satellite laser communication is a promising solution to satisfy the increasing demand for high-capacity wireless communications. Satellite laser communication has several advantages over its radio frequency counterparts, such as a higher capacity with a broader bandwidth and transmission security provided by highly directional laser beams. However, the received optical power fluctuations induced by atmospheric scintillation cause burst errors, requiring the employment of high-performance error correction codes, such as turbo or low-density parity check (LDPC) codes. Recently, polar code has been attracting significant attention, primarily because of its lower encoding and decoding computational complexity and its high performance, reaching the Shannon limit. We have reported a long-distance experiment using 7.8-km terrestrial free-space optical (FSO) communication links and compared the performance of polar and LDPC codes. Our experimental results revealed the advantage of polar codes over LDPC codes when channel state information (CSI) was not available. In FSO communications suffering from atmospheric fading, it is known that we can enhance the error-correction performance of these codes by utilizing a channel equalization technique based on the estimated CSI. In this study, we present the results of long-distance transmission experiments using polar codes with channel equalization. As a result, equalization improves the error-correction performance. Moreover, even with channel equalization, the block error rate of polar codes is better than that of LDPC codes, as in our previous report.

Rechargeable sodium ion batteries with high energy density are a promising technology to address the demand for grid storage. Cathode materials with oxygen redox activity exhibit higher energy density than expected from Na-ion removal and charge compensation solely by transition metal redox. One strategy to enable oxygen redox in materials is to alter the oxygen environment through transition metal layer ordering. In this work, we report the investigation of oxygen redox activity induced by transition metal ordering in P2-type Na0.8Li0.12Ni0.22Mn0.66O2 cathode synthesized by carbonate co-precipitation. Irreversible oxygen activity was observed and correlated with Ni migration that resulted in the loss of transition metal ordering in the structure. Calculated density of states shows that after Ni migration, the number of unoccupied states of O above Fermi level decreases, inhibiting the reduction of oxygen during sodiation. This paper provides insights on how Ni migration has a detrimental effect on transition metal ordering and reversibility of oxygen redox at high voltage.

Background Patients with thrombocytopenia associated with chronic liver disease (CLD) are at greater risk of bleeding during invasive procedures. This study characterized the pharmacokinetic/pharmacodynamic (PK/PD) profile of lusutrombopag, a novel thrombopoietin-receptor agonist, using modelling and simulation, and evaluated the appropriate dose regimen for treatment of thrombocytopenia in CLD patients undergoing invasive procedures. Methods A population PK/PD model was developed using plasma lusutrombopag concentrations from 78 healthy subjects and 349 CLD patients, as well as platelet counts from 347 of these 349 patients. Covariates were explored from subject characteristics. Monte-Carlo simulations were performed to assess a dose response for efficacy (platelet counts ≥ 50,000/μL) and a risk for platelet overshooting (platelet counts > 200,000/μL). Results Visual predictive checks indicated the developed models described the PK/PD profile of lusutrombopag well. In the simulations, without stopping criteria, lusutrombopag 3 mg once daily for 7 days before scheduled invasive procedures provided effective platelet response (85.2% probability for efficacy). The probability of platelet overshooting was 1.2%, indicating that platelet monitoring is not necessary. Although body weight was an influential covariate on the pharmacokinetics of lusutrombopag, individually estimated peak platelet counts overlapped among the body weight groups, suggesting no clinically significant effect on body weight. Conclusion The modelling and simulation support lusutrombopag 3 mg once daily for 7 days without platelet monitoring. Electronic supplementary material The online version of this article (10.1007/s40262-019-00770-4) contains supplementary material, which is available to authorized users.

We theoretically investigate the preparation of mid-infrared (MIR) spectrally-uncorrelated biphotons from a spontaneous parametric down-conversion process using doped LN crystals, including MgO doped LN, ZnO doped LN, and In2O3 doped ZnLN with doping ratio from 0 to 7 mol%. The tilt angle of the phase-matching function and the corresponding poling period are calculated under type-II, type-I, and type-0 phase-matching conditions. We also calculate the thermal properties of the doped LN crystals and their performance in Hong-Ou-Mandel interference. It is found that the doping ratio has a substantial impact on the group-velocity-matching (GVM) wavelengths. Especially, the GVM2 wavelength of co-doped InZnLN crystal has a tunable range of 678.7 nm, which is much broader than the tunable range of less than 100 nm achieved by the conventional method of adjusting the temperature. It can be concluded that the doping ratio can be utilized as a degree of freedom to manipulate the biphoton state. The spectrally uncorrelated biphotons can be used to prepare pure single-photon source and entangled photon source, which may have promising applications for quantum-enhanced sensing, imaging, and communications at the MIR range., 11 pages, 9 figures

The solid electrolyte interphase (SEI) is regarded as the most complex but the least understood constituent in secondary batteries using liquid and solid electrolytes. The nanostructures of SEIs were recently reported to be equally important to the chemistry of SEIs for stabilizing Li metal in liquid electrolyte. However, the dearth of such knowledge in all-solid-state battery (ASSB) has hindered a complete understanding of how certain solid-state electrolytes, such as LiPON, manifest exemplary stability against Li metal. Characterizing such solid-solid interfaces is difficult due to the buried, highly reactive, and beam-sensitive nature of the constituents within. By employing cryogenic electron microscopy (cryo-EM), the interphase between Li metal and LiPON is successfully preserved and probed, revealing a multilayer mosaic SEI structure with concentration gradients of nitrogen and phosphorous, materializing as crystallites within an amorphous matrix. This unique SEI nanostructure is less than 80 nm and is shown stable and free of any organic lithium containing species or lithium fluoride components, in contrast to SEIs often found in state-of-the-art organic liquid electrolytes. Our findings reveal insights on the nanostructures and chemistry of such SEIs as a key component in lithium metal batteries to stabilize Li metal anode.

Ultrafast quantum optics with time-frequency entangled photons is at the forefront of progress towards future quantum technologies. However, to unravel the time domain structure of entangled photons and exploit fully their rich dimensionality, a single-photon detector with sub-picosecond temporal resolution is required. Here, we present ultrafast single-photon detection using an optical Kerr gate composed of a photonic crystal fiber (PCF) placed inside a Sagnac interferometer. A near-rectangle temporal waveform of a heralded single-photon generated via spontaneous parametric down-conversion is measured with temporal resolution as high as 224 ± 9 fs. The large nonlinearity and long effective interaction length of the PCF enables maximum detection efficiency to be achieved with only 30.5 mW gating pulse average power, demonstrating an order-of-magnitude improvement compared to optical gating with sum-frequency generation. Also, we discuss the trade-off relationship between detection efficiency and temporal resolution.

The solid electrolyte interphase (SEI) is regarded as the most complex but the least understood constituent in secondary batteries using liquid and solid electrolytes. The nanostructures of SEIs were recently reported to be equally important to the chemistry of SEIs for stabilizing Li metal in liquid electrolyte. However, the dearth of such knowledge in all-solid-state battery (ASSB) has hindered a complete understanding of how certain solid-state electrolytes, such as LiPON, manifest exemplary stability against Li metal. Characterizing such solid-solid interfaces is difficult due to the buried, highly reactive, and beam-sensitive nature of the constituents within. By employing cryogenic electron microscopy (cryo-EM), the interphase between Li metal and LiPON is successfully preserved and probed, revealing a multilayer mosaic SEI structure with concentration gradients of nitrogen and phosphorous, materializing as crystallites within an amorphous matrix. This unique SEI nanostructure is less than 80 nm and is shown stable and free of any organic lithium containing species or lithium fluoride components, in contrast to SEIs often found in state-of-the-art organic liquid electrolytes. Our findings reveal insights on the nanostructures and chemistry of such SEIs as a key component in lithium metal batteries to stabilize Li metal anode.

Conventional optical synthesis, the manipulation of the phase and amplitude of spectral components to produce an optical pulse in different temporal modes, is revolutionizing ultrafast optical science and metrology. These technologies rely on the Fourier transform of light fields between time and frequency domains in one-dimensional space. However, within this treatment it is impossible to incorporate the quantum correlation among photons. Here we expand the Fourier synthesis into high dimensional space to deal with the quantum correlation, and carry out an experimental demonstration by manipulating the two-photon probability distribution of a biphoton in two-dimensional time and frequency space. As a potential application, we show manipulation of a heralded single-photon wave packet, which is never explained by the conventional one-dimensional Fourier optics. Our approach opens up a new pathway to tailor the temporal characteristics of a biphoton wave packet with high dimensional quantum-mechanical treatment. We anticipate such high dimensional treatment of light in time and frequency domains could bridge the research fields between quantum optics and ultrafast optical measurements., Comment: 12 pages, 7 figures

Light-harvesting efficiency can be prominently increased by using ternary blend polymer solar cells, in which a wide-bandgap crystalline polymer is incorporated into a binary blend of a low-bandgap polymer and a fullerene derivative. This is partly due to the complementary absorption bands over a wide wavelength range, and partly ascribed to the thick photoactive layer. As a result, the best power conversion efficiency of 9.40% was obtained for the ternary blend device with a thickness of ≈300 nm.

This study extends Hirano and Yanagawa (Rev Econ Stud 84(1):406–443, 2017) to an asymmetric two-country model and examines bubbles effects on each country’s long-run economic growth rate. This study also provides numerical examples with respect to the relationship between each country’s growth rate and their financial frictions in the balanced growth equilibria with bubbles and without bubbles. It shows that foreign bubbles have positive and negative effects on both countries’ growth rates, and which effect dominates depends on the level of financial development in both countries. In this study, the positive effect of bubbles tends to dominate when the total level of financial frictions in both countries is relatively low. When the total effect of bubbles on the growth rate is positive, the burst of foreign bubbles leads to a decrease in the growth rate in both countries. This implies that there is a positive correlation between foreign bubbles and the domestic as well as the foreign country’s growth rate.

We experimentally demonstrate a polarization-entangled photon source at 810 nm using a type-II phase-matched periodically poled potassium titanyl phosphate (PPKTP) crystal pumped by a low-cost, broadband laser diode with a central wavelength of 405 nm and a typical bandwidth of 0.53 nm. The PPKTP crystal is placed in a Sagnac loop to realize the compact size and high stability. The downconverted biphotons, the signal and the idler, have typical bandwidths of 5.57 and 7.32 nm. We prepare two Bell states | Ψ + ⟩ and | Ψ − ⟩ with the fidelities of 0.948 ± 0.004 and 0.963 ± 0.002 . In the polarization correlation measurement, the visibilities are all higher than 96.2%, and in the Bell inequality test, the S value can achieve 2.78 ± 0.01 . This high-quality and low-cost entangled photon source may have many practical applications in quantum information processing.

Summary Silicon with a high theoretical capacity (3,579 mAh/g) is a promising anode candidate for lithium-ion batteries. However, commercialization is still impeded by low Coulombic efficiency, caused by solid electrolyte interphase (SEI) formation and trapped lithium (Li)-silicon (Si) alloy during repeated volume change. Quantifying capacity losses from each factor is crucial to formulate rational design strategies for further improvement. In this work, titration-gas chromatography and cryogenic transmission electron microscopy are applied to characterize the evolution of trapped Li-Si alloy and SEI growth in a silicon thin-film anode. It is found that continuous growth of the SEI is the dominant factor for lithium inventory loss during cycling, with only a marginal increase in trapped Li-Si alloy. This study offers a quantitative approach to differentiate Li in the SEI from trapped Li in Li-Si alloy through a silicon thin-film anode, providing unique insights into identifying critical bottlenecks for developing Si anodes.

Spectrally intrinsically uncorrelated biphoton states generated from nonlinear crystals are very important but rare resources for quantum photonics and quantum information applications. Previously, such biphoton states were generated from several kinds of crystals, however, their wavelength ranges and nonlinear efficiencies were still limited for various applications. In order to explore new crystal for wider wavelength range and higher nonlinear efficiency, here we theoretically study the generation of spectrally uncorrelated biphoton states from 14 crystals in the `BBO family', including BBO, CLBO, KABO, KBBF, RBBF, CBBF, BABF, BiBO, LBO, CBO, LRB4, LCB, YCOB, and GdCOB. They satisfy three kinds of group-velocity matching condition from near-infrared to telecom wavelengths. Furthermore, heralded single photons can be generated with a purity as high as 0.98, which is achieved without any narrow filtering. The indistinguishability of photons from independent sources is examined by the Hong-Ou-Mandel interference, which results in a visibility of 98% also without any further filtering, i.e., photons from different heralded single-photon sources are highly indistinguishable. Our study may provide single-photon sources with good performance for quantum information processing at near-infrared and telecom wavelengths., Comment: 10 pages, 6 figures

Light incident upon molecules trigger fundamental processes in diverse systems present in nature. However, under natural conditions, such as sunlight illumination, it is impossible to assign known times for photon arrival owing to continuous pumping, and therefore, the photo-induced processes cannot be easily investigated. In this work, we theoretically demonstrate that characteristics of sunlight photons such as photon number statistics and spectral distribution can be emulated through quantum entangled photon pair generated with the parametric down-conversion (PDC). We show that the average photon number of the sunlight in a specific frequency spectrum, e.g., the visible light, can be reconstructed by adjusting the PDC crystal length and pump frequency, and thereby molecular dynamics induced by the pseudo-sunlight can be investigated. The entanglement time, which is the hallmark of quantum entangled photons, can serve as a control knob to resolve the photon arrival times, enabling investigations on real-time dynamics triggered by the pseudo-sunlight photons., Comment: 7 pages

We report a simple scheme for direct generation of frequency-bin entangled photon pairs via spontaneous parametric downconversion. Our fabricated nonlinear optical crystal with two different poling periods can simultaneously satisfy two different, spectrally symmetric nondegenerate quasi-phase-matching conditions, enabling the direct generation of entanglement in two discrete frequency-bin modes. Our produced photon pairs exhibited Hong-Ou-Mandel interference with high-visibility beating oscillations, a signature of two-mode frequency-bin entanglement. Moreover, we demonstrate deterministic entanglement-mode conversion from frequency-bin to polarization modes, with which our source can be more versatile for various quantum applications. Our scheme can be extended to direct generation of high-dimensional frequency-bin entanglement, and thus will be a key technology for frequency-multiplexed optical quantum information processing.

The rapidly growing technological demand for lithium-ion batteries has prompted the development of novel cathode materials with high energy density, low cost, and improved safety. High voltage spinel, LiNi0.5Mn1.5O4 (LNMO), is one of the most promising candidates yet to be commercialized. The two primary obstacles for this material are the inferior electronic conductivity and fast capacity degradation in full cells due to the high operating voltage. By systematically addressing these limitations, we successfully develop a thick LNMO electrode with areal capacity loadings up to 3 mAh·cm−2. The optimized thick electrode is paired with a commercial graphite anode at both the coin cell and pouch cell level, achieving a full cell capacity retention as high as 72% and 78%, respectively, after 300 cycles. We attribute this superior cycling stability to careful optimizations of cell components and testing conditions, with a specific focus improving electronic conductivity and high voltage compatibility. These results suggest precise control of materials quality, electrode architecture and electrolyte optimization can soon support the development of a cobalt-free battery system based on a thick LNMO cathode (>4 mAh·cm2), which will eventually meet the needs of next-generation Li-ion batteries with reduced cost, improved safety, and assured sustainability.

Free-space optical (FSO) communications can offer secure connectivity thanks to the high directionality of the laser beam and the line-of-sight configuration. These security advantages are employed to realize high-speed key establishment between two distant parties, which is provably secure against an eavesdropper with unlimited computational resources. Besides, a well-maintained laser beam divergence allows group key agreement (GKA) among multiple parties. Here, we propose a novel method of GKA over FSO link—FSO-GKA. After numerically characterizing fundamental behaviors, we present a proof-of-concept demonstration of FSO-GKA using a 7.8-km terrestrial link. We achieve a group key rate of roughly 8 Mbps over a 58dB-loss channel based on 10-MHz on-off keying. We also investigate information leakage risks under several atmospheric conditions, which provides the basis for security certification of FSO-GKA. Our proposed scheme shows a new way to construct high-speed key exchange platforms.

Time-frequency duality plays a pivotal role in modern optical science and engineering. Conventional duality, which is connected by one-dimensional Fourier transformation, is insufficient for characterizing quantum mechanical correlations in the time-frequency behavior of multiple photons; a higher-dimensional treatment is required. The authors directly measure the two-photon distributions of generated biphotons in both frequency and time domains, and show that they satisfy the Fourier-limited condition in two-dimensional time and frequency space, but not in conventional one-dimensional space. This study helps to pave the way to tomorrow's quantum optical technologies.

In this work, we experimentally manipulate the spectrum and phase of a biphoton wave packet in a two-dimensional frequency space. The spectrum is shaped by adjusting the temperature of the crystal, and the phase is controlled by tilting the dispersive glass plate. The manipulating effects are confirmed by measuring the two-photon spectral intensity (TSI) and the Hong-Ou-Mandel (HOM) interference patterns. Unlike the previous independent manipulation schemes, here we perform joint manipulation on the biphoton spectrum. The technique in this work paves the way for arbitrary shaping of a multi-photon wave packet in a quantum manner., Comment: 4 pages, 4 figures