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<jats:p> <jats:italic>We utilize high-resolution resonant angle-resolved photoemission spectroscopy (ARPES) to study the band structure and hybridization effect of the heavy-fermion compound Ce<jats:sub>2</jats:sub>IrIn<jats:sub>8</jats:sub>. We observe a nearly flat band at the binding energy of 7 meV below the coherent temperature <jats:inline-formula> <jats:tex-math><?CDATA ${T}_{\mathrm{coh}}\sim 40\,{\rm{K}}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>T</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>coh</mml:mi> </mml:mrow> </mml:msub> <mml:mo>∼</mml:mo> <mml:mn>40</mml:mn> <mml:mspace width="0.25em" /> <mml:mi mathvariant="normal">K</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpl_36_9_097101_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, which characterizes the electrical resistance maximum and indicates the onset temperature of hybridization. However, the Fermi vector and the Fermi surface volume have little change around <jats:italic>T</jats:italic> <jats:sub>coh</jats:sub>, which challenges the widely believed evolution from a high-temperature small Fermi surface to a low-temperature large Fermi surface. Our experimental results of the band structure fit well with the density functional theory plus dynamic mean-field theory calculations.</jats:italic> </jats:p>

<jats:p> <jats:italic>Two-dimensional (2D) InSe and WS<jats:sub>2</jats:sub> exhibit promising characteristics for optoelectronic applications. However, they both have poor absorption of visible light due to wide bandgaps: 2D InSe has high electron mobility but low hole mobility, while 2D WS<jats:sub>2</jats:sub> is on the contrary. We propose a 2D heterostructure composed of their monolayers as a solution to both problems. Our first-principles calculations show that the heterostructure has a type-II band alignment as expected. Consequently, the bandgap of the heterostructure is reduced to 2.19 eV, which is much smaller than those of the monolayers. The reduction in bandgap leads to a considerable enhancement of the visible-light absorption, such as about fivefold (threefold) increase in comparison to monolayer InSe (WS<jats:sub>2</jats:sub>) at the wavelength of 490 nm. Meanwhile, the type-II band alignment also facilitates the spatial separation of photogenerated electron-hole pairs; i.e., electrons (holes) reside preferably in the InSe (WS<jats:sub>2</jats:sub>) layer. As a result, the two layers complement each other in carrier mobilities of the heterostructure: the photogenerated electrons and holes inherit the large mobilities from the InSe and WS<jats:sub>2</jats:sub> monolayers, respectively.</jats:italic> </jats:p>

<jats:p> <jats:italic>Magnetization switching is one of the most fundamental topics in the field of magnetism. Machine learning (ML) models of random forest (RF), support vector machine (SVM), deep neural network (DNN) methods are built and trained to classify the magnetization reversal and non-reversal cases of single-domain particle, and the classification performances are evaluated by comparison with micromagnetic simulations. The results show that the ML models have achieved great accuracy and the DNN model reaches the best area under curve (AUC) of 0.997, even with a small training dataset, and RF and SVM models have lower AUCs of 0.964 and 0.836, respectively. This work validates the potential of ML applications in studies of magnetization switching and provides the benchmark for further ML studies in magnetization switching.</jats:italic> </jats:p>

<jats:p> <jats:italic>Mn-based Heusler alloys have attracted significant research attention as half-metallic materials because of their giant magnetocrystalline anisotropy and magnetocaloric properties. We investigate the crystal structure and magnetic properties of polycrystalline, [101]-oriented, and [100]-oriented <jats:inline-formula> <jats:tex-math><?CDATA ${\mathrm{Mn}}_{2-\delta }\mathrm{Sn}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>Mn</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> <mml:mo>−</mml:mo> <mml:mi>δ</mml:mi> </mml:mrow> </mml:msub> <mml:mi>Sn</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpl_36_9_097502_ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> prepared separately by arc melting, the Bridgeman method, and the flux method. All of these compounds crystallize in a Ni<jats:sub>2</jats:sub>In-type structure. In the <jats:inline-formula> <jats:tex-math><?CDATA ${\mathrm{Mn}}_{2-\delta }\mathrm{Sn}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>Mn</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> <mml:mo>−</mml:mo> <mml:mi>δ</mml:mi> </mml:mrow> </mml:msub> <mml:mi>Sn</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpl_36_9_097502_ieqn4.gif" xlink:type="simple" /> </jats:inline-formula> lattice, Mn atoms occupy all of the 2<jats:italic>a</jats:italic> and a fraction of the 2<jats:italic>d</jats:italic> sites. Site disorder exists between Mn and Sn atoms in the 2<jats:italic>c</jats:italic> sites. In addition, these compounds undergo a re-entrant spin-glass-like transition at low temperatures, which is caused by frustration and randomness within the spin system. The magnetic properties of these systems depend on the crystal directions, which means that the magnetic interactions differ significantly along different directions. Furthermore, these materials exhibit a giant magnetocaloric effect near the Curie temperature. The largest value of maximum of magnetic entropy change (<jats:inline-formula> <jats:tex-math><?CDATA $-{\rm{\Delta }}{S}_{{\rm{M}}})$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>−</mml:mo> <mml:mi mathvariant="normal">Δ</mml:mi> <mml:msub> <mml:mrow> <mml:mi>S</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">M</mml:mi> </mml:mrow> </mml:msub> <mml:mo stretchy="false">)</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpl_36_9_097502_ieqn5.gif" xlink:type="simple" /> </jats:inline-formula> occurs perpendicular to the [100] direction. Specifically, at 252 K, maximum <jats:inline-formula> <jats:tex-math><?CDATA $-{\rm{\Delta }}{S}_{{\rm{M}}}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>−</mml:mo> <mml:mi mathvariant="normal">Δ</mml:mi> <mml:msub> <mml:mrow> <mml:mi>S</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">M</mml:mi> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpl_36_9_097502_ieqn6.gif" xlink:type="simple" /> </jats:inline-formula> is 2.91 and <jats:inline-formula> <jats:tex-math><?CDATA $3.64\,{\rm{J}}\cdot {\mathrm{kg}}^{-1}{{\rm{K}}}^{-1}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>3.64</mml:mn> <mml:mspace width="0.25em" /> <mml:mi mathvariant="normal">J</mml:mi> <mml:mo>·</mml:mo> <mml:msup> <mml:mrow> <mml:mi>kg</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">K</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpl_36_9_097502_ieqn7.gif" xlink:type="simple" /> </jats:inline-formula> for a magnetic field of 5 and 7 T, respectively. The working temperature span over 80 K and the relative cooling power reaches 302 J/kg for a magnetic field of 7 T, which makes the <jats:inline-formula> <jats:tex-math><?CDATA ${\mathrm{Mn}}_{2-\delta }\mathrm{Sn}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>Mn</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> <mml:mo>−</mml:mo> <mml:mi>δ</mml:mi> </mml:mrow> </mml:msub> <mml:mi>Sn</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpl_36_9_097502_ieqn8.gif" xlink:type="simple" /> </jats:inline-formula> compound a promising candidate for a magnetic refrigerator.</jats:italic> </jats:p>

<jats:p> <jats:italic>The Debye relaxation of dielectric spectroscopy exists extensively in monohydroxy alcohols. We model the relaxation based on the infinite-pseudospin-chain Ising model and the Glauber dynamics, and the corresponding complex permittivity is obtained. The model results are in good agreement with the experimental data of 3,7-dimethyl-1-octanol, 2-ethyl-1-hexanol and 5-methyl-2-hexanol in a wide temperature range. Moreover, in the model parameters, the sum of the mean-field interaction energy and two times the orientation is nearly twice the hydrogen bond energy, which further states the rationality of this model.</jats:italic> </jats:p>

<jats:p> <jats:italic>The critical adsorption of semi-flexible polymer chains on attractive surfaces is studied using Monte Carlo simulations. The results reveal that the critical adsorption point of a free polymer chain is the same as that of an end-grafted one. For the end-grafted polymer, we find that the finite-size scaling relation and the maximum fluctuation of adsorbed monomers are equivalent in estimating the critical adsorption point. The effect of chain stiffness on the critical adsorption is also investigated. The surface attraction strength for the critical adsorption of semi-flexible polymer chain decreases exponentially with an increase in the chain stiffness; In other words, lower adsorption energy is needed to adsorb a stiffer polymer chain. The result is explained from the viewpoint of the free energy profile for the adsorption.</jats:italic> </jats:p>

<jats:p> <jats:italic>We design and fabricate a good performance silicon photoconductive terahertz detector on sapphire substrates at room temperature. The best voltage responsivity of the detector is 6679V/W at frequency 300 GHz as well as low voltage noise of 3.8 nV/Hz<jats:sup>1/2</jats:sup> for noise equivalent power 0.57 pW/Hz<jats:sup>1/2</jats:sup>. The measured response time of the device is about <jats:inline-formula> <jats:tex-math><?CDATA $9\,\mu {\rm{s}}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>9</mml:mn> <mml:mspace width="0.25em" /> <mml:mi>μ</mml:mi> <mml:mi mathvariant="normal">s</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpl_36_9_098501_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, demonstrating that the detector has a speed of <jats:inline-formula> <jats:tex-math><?CDATA $\gt 110\,\mathrm{kHz}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>&gt;</mml:mo> <mml:mn>110</mml:mn> <mml:mspace width="0.25em" /> <mml:mi>kHz</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpl_36_9_098501_ieqn2.gif" xlink:type="simple" /> </jats:inline-formula>. The achieved good performance, together with large detector size (acceptance area is 3 <jats:inline-formula> <jats:tex-math><?CDATA $\mu {\rm{m}}\times 160\,\mu {\rm{m}}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>μ</mml:mi> <mml:mi mathvariant="normal">m</mml:mi> <mml:mo>×</mml:mo> <mml:mn>160</mml:mn> <mml:mspace width="0.25em" /> <mml:mi>μ</mml:mi> <mml:mi mathvariant="normal">m</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpl_36_9_098501_ieqn3.gif" xlink:type="simple" /> </jats:inline-formula>), simple structure, easy manufacturing method, compatibility with mature silicon technology, and suitability for large-scale fabrication of imaging arrays provide a promising approach to the development of sensitive terahertz room-temperature detectors.</jats:italic> </jats:p>

<jats:p> <jats:italic>Using the single-mode approximation, we study entanglement measures including two independent quantities; i.e., negativity and von Neumann entropy for a tripartite generalized Greenberger–Horne–Zeilinger (GHZ) state in noninertial frames. Based on the calculated negativity, we study the whole entanglement measures named as the algebraic average π</jats:italic> <jats:sub>3</jats:sub> <jats:italic>-tangle and geometric average Π</jats:italic> <jats:sub>3</jats:sub> <jats:italic>-tangle. We find that the difference between them is very small or disappears with the increase of the number of accelerated qubits. The entanglement properties are discussed from one accelerated observer and others remaining stationary to all three accelerated observers. The results show that there will always exist entanglement, even if acceleration r arrives to infinity. The degree of entanglement for all 1–1 tangles are always equal to zero, but 1–2 tangles always decrease with the acceleration parameter r. We notice that the von Neumann entropy increases with the number of the accelerated observers and S</jats:italic> <jats:sub> <jats:italic>κ</jats:italic> <jats:sub>I</jats:sub> <jats:italic>ζ</jats:italic> <jats:sub>I</jats:sub> </jats:sub> (<jats:italic>κ, ζ</jats:italic> ∈ (A, B, C)) <jats:italic>first increases and then decreases with the acceleration parameter r. This implies that the subsystem ρ</jats:italic> <jats:sub> <jats:italic>κ</jats:italic> <jats:sub>I</jats:sub> <jats:italic>ζ</jats:italic> <jats:sub>I</jats:sub> </jats:sub> <jats:italic>is first more disorder and then the disorder will be reduced as the acceleration parameter r increases. Moreover, it is found that the von Neumann entropies S</jats:italic> <jats:sub>ABCI</jats:sub>, <jats:italic>S</jats:italic> <jats:sub>ABICI</jats:sub> <jats:italic>and S</jats:italic> <jats:sub>AIBICI</jats:sub> <jats:italic>always decrease with the controllable angle θ, while the entropies of the bipartite subsystems S</jats:italic> <jats:sub>2−2<jats:sub>non</jats:sub> </jats:sub> <jats:italic>(two accelerated qubits), S</jats:italic> <jats:sub>2-1<jats:sub>non</jats:sub> </jats:sub> <jats:italic>(one accelerated qubit) and S</jats:italic> <jats:sub>2-0<jats:sub>non</jats:sub> </jats:sub> <jats:italic>(without accelerated qubit) first increase with the angle θ and then decrease with it.</jats:italic> </jats:p>

<jats:p> <jats:italic>We characterize a modified continuous-variable quantum key distribution (CV-QKD) protocol with four states in the middle of a quantum channel. In this protocol, two noiseless linear amplifiers (NLAs) are inserted before each detector of the two parts, Alice and Bob, with the purpose of increasing the secret key rate and the maximum transmission distance. We present the performance analysis of the new four-state CV-QKD protocol over a Gaussian lossy and noisy channel. The simulation results show that the NLAs with a reasonable gain g can effectively enhance the secret key rate as well as the maximum transmission distance, which is generally satisfied in practice.</jats:italic> </jats:p>

<jats:p> <jats:italic>Learning the Hamiltonian of a quantum system is indispensable for prediction of the system dynamics and realization of high fidelity quantum gates. However, it is a significant challenge to efficiently characterize the Hamiltonian which has a Hilbert space dimension exponentially growing with the system size. Here, we develop and implement an adaptive method to learn the effective Hamiltonian of an 11-qubit quantum system consisting of one electron spin and ten nuclear spins associated with a single nitrogen-vacancy center in a diamond. We validate the estimated Hamiltonian by designing universal quantum gates based on the learnt Hamiltonian and implementing these gates in the experiment. Our experimental result demonstrates a well-characterized 11-qubit quantum spin register with the ability to test quantum algorithms, and shows our Hamiltonian learning method as a useful tool for characterizing the Hamiltonian of the nodes in a quantum network with solid-state spin qubits.</jats:italic> </jats:p>