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KTl2 crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. K is bonded to six equivalent Tl atoms to form distorted edge-sharing KTl6 octahedra. All K–Tl bond lengths are 3.58 Å. Tl is bonded in a 6-coordinate geometry to three equivalent K and three equivalent Tl atoms. All Tl–Tl bond lengths are 3.28 Å.
Small area (less than 1 sq micron), high-current-density NbN/MgO/NbN tunnel junctions with I-V characteristics suitable for high-frequency mixers have been fabricated. Mesa-geometry junctions with an area of about 1 sq micron and critical current density of 5-10 kA/sq cm are integrated with superconducting microstrip lines designed to resonate out the junction capacitance. A study was made of the mixer gain and noise performance near 205 GHz as a function of the inductance provided by the microstrip line. This has confirmed, at a high millimeter-wave frequency, values of junction capacitance of 85 fF/sq micron and recently measured values of a magnetic penetration depth of 380 nm. Mixer noise temperatures as low as 134 K at 1.5 K have been obtained for properly tuned junctions. A significant improvement in mixer performance on cooling from 4.2 K to 1.5 K was observed. Edge-geometry junctions with an area of 0.3 sq microns and critical current density of 18-25 kA/sq cm have also been fabricated. These junctions give a mixer noise temperature of 145 K at 4.2 K without the use of integrated tuning elements. These are the best results ever achieved for NbN-based SIS mixers.
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Wind tunnel test of ground effect of 35-deg swept- back wing jet transport equipped with boundary layer control, trailing & leading edge flaps
The Cosmology Large Angular Scale Surveyor (CLASS) instrument will measure the polarization of the cosmic microwave background at 40, 90, and 150 GHz from Cerro Toco in the Atacama desert of northern Chile. In this paper, we describe the optical design of the 40 GHz telescope system. The telescope is a diffraction limited catadioptric design consisting of a front-end Variable-delay Polarization Modulator (VPM), two ambient temperature mirrors, two cryogenic dielectric lenses, thermal blocking filters, and an array of 36 smooth-wall scalar feedhorn antennas. The feed horns guide the signal to antenna-coupled transition-edge sensor (TES) bolometers. Polarization diplexing and bandpass definition are handled on the same microchip as the TES. The feed horn beams are truncated with 10 dB edge taper by a 4 K Lyot-stop to limit detector loading from stray light and control the edge illumination of the front-end VPM. The field-of-view is 19 deg x 14 deg with a resolution for each beam on the sky of 1.5 deg. FWHM.
The validity of the Tada stress intensity factor (K Tada ) for pinned-ends single edge notch tension [SEN(T)] specimens is assessed via a combined experimental-modeling approach. Analysis of fatigue crack growth rate reductions during constant-∆K Tada loading demonstrates that specific combinations of alloy stiffness, geometry, and loading result in the true K deviating below K Tada . Geometrically non-linear, 3-dimensional finite element calculations confirm mild-to-strong influences of these parameters, which are not captured by K Tada . Most existing pinned SEN(T) data are found to use parameters where KTada is not significantly reduced, but the present results underscore the need for a more broadly applicable K solution.
K(NO2)3Cd crystallizes in the cubic Pm-3 space group. The structure is three-dimensional and consists of one cadmium molecule and one K(NO2)3 framework. In the K(NO2)3 framework, K1+ is bonded to twelve equivalent O2- atoms to form edge-sharing KO12 cuboctahedra. All K–O bond lengths are 3.46 Å. N3+ is bonded in a linear geometry to two equivalent O2- atoms. Both N–O bond lengths are 1.25 Å. O2- is bonded in a single-bond geometry to two equivalent K1+ and one N3+ atom.
K(As2O3)2Br crystallizes in the hexagonal P6/mmm space group. The structure is two-dimensional and consists of one hydrobromic acid molecule and one K(As2O3)2 sheet oriented in the (0, 0, 1) direction. In the K(As2O3)2 sheet, K1+ is bonded to twelve equivalent O2- atoms to form edge-sharing KO12 cuboctahedra. All K–O bond lengths are 3.17 Å. As3+ is bonded in a distorted T-shaped geometry to three equivalent O2- atoms. All As–O bond lengths are 1.84 Å. O2- is bonded in a distorted bent 120 degrees geometry to two equivalent K1+ and two equivalent As3+ atoms.
K(As2O3)2I crystallizes in the hexagonal P6/mmm space group. The structure is two-dimensional and consists of one hydriodic acid molecule and one K(As2O3)2 sheet oriented in the (0, 0, 1) direction. In the K(As2O3)2 sheet, K1+ is bonded to twelve equivalent O2- atoms to form edge-sharing KO12 cuboctahedra. All K–O bond lengths are 3.19 Å. As3+ is bonded in a distorted T-shaped geometry to three equivalent O2- atoms. All As–O bond lengths are 1.84 Å. O2- is bonded in a distorted bent 120 degrees geometry to two equivalent K1+ and two equivalent As3+ atoms.
(K(As2O3)2)2Cl2 crystallizes in the hexagonal P6/mmm space group. The structure is two-dimensional and consists of one hydrochloric acid molecule and one K(As2O3)2 sheet oriented in the (0, 0, 1) direction. In the K(As2O3)2 sheet, K1+ is bonded to twelve equivalent O2- atoms to form edge-sharing KO12 cuboctahedra. All K–O bond lengths are 3.17 Å. As3+ is bonded in a distorted T-shaped geometry to three equivalent O2- atoms. All As–O bond lengths are 1.84 Å. O2- is bonded in a distorted bent 120 degrees geometry to two equivalent K1+ and two equivalent As3+ atoms.
Uranium mononitride (UN) is a promising advanced nuclear fuel due to its high thermal conductivity and high fissile density. However, many aspects of its mechanical behavior, particularly at reactor-relevant conditions, remain unclear. In this study, molecular dynamics (MD) simulations were employed to investigate the deformation behavior and dislocation motion in UN. We found that the Kocevski potential predicts the principal slip system as $\frac{1}{2}$ $\langle110\rangle${110}, aligning with experimental data. On the other hand, the Tseplyaev potential predicts slip to primarily occur on $\frac{1}{2}$ $\langle110\rangle${111}. MD simulations of stress–strain behavior were used to estimate the nanoindentation hardness, revealing that the Kocevski potential accurately predicts hardness even though it fails to model dynamic plasticity. Complete dislocation mobility functions have been fitted for the edge and screw dislocations in both the thermally activated and phonon-drag regimes. The 300 K linear mobility of the edge dislocation using the Tseplyaev potential was found to be 817 Pa -1 ·s -1 , whereas that of the screw dislocation using the Kocevski potential was found to be 4546 Pa -1 ·s -1 . At intermediate stresses, we observed that the subsonic steady-state motion of the edge dislocation in UN is intermittently interrupted by velocity jumps, reaching the average sound velocity. Finally, the threshold Schmid stress is calculated as 179–197 MPa, which gives an upper-limit estimate of the uniaxial yield stress of polycrystalline UN of 548–603 MPa. These findings, including the fitted dislocation mobility function, provide essential input for future plasticity and dislocation dynamics models of nuclear fuels.
Hot carrier extraction occurs in 2D semiconductor photoelectrochemical cells. Boosting the energy efficiency of hot carrier-based photoelectrochemical cells requires maximizing the hot carrier extraction rate relative to the cooling rate. One could expect to tune the hot carrier extraction rate constant (k ET ) via a Marcus–Gerischer relationship, where k ET depends exponentially on ΔG°' (the standard driving force for interfacial electron transfer). ΔG°' is defined as the energy level difference between a semiconductor's conduction/valence band (CB/VB) minima/maxima and the redox potential of reactant molecules in solution. A major challenge in the electrochemistry community is that conventional approaches to quantify ΔG°' for bulk semiconductors (e.g., Mott–Schottky measurements) cannot be directly applied to ultrathin 2D electrodes. The specific problem is that enormous electronic bandgap changes (>0.5 eV) and CB/VB edge movement take place upon illuminating or applying a potential to a 2D semiconductor electrode. Here, we develop an in situ absorbance spectroscopy approach to quantify interfacial energetics of 2D semiconductor/electrolyte interfaces using a minimal many-body model. Our results show that band edge movement in monolayer MoS 2 is significant (0.2–0.5 eV) over a narrow range of applied potentials (0.2–0.3 V). Such large band edge shifts could change k ET by a factor of 10–100, which has important consequences for practical solar energy conversion applications. We discuss the current experimental and theoretical knowledge gaps that must be addressed to minimize the error in the proposed optical approach.
Efficient charge transport remains a fundamental challenge for nanoelectronic devices, as their performance is constrained by high dissipation and the impedance mismatch between high-frequency signal sources and nanoscale circuit interfaces. Although topologically protected helical edge modes offer a dissipationless and backscattering-resilient alternative, achieving nanoscale control over these modes requires direct visualization of their spatial electrodynamics, especially under high-frequency operation. Here, by utilizing cryogenic magneto-infrared scattering-type scanning near-field optical microscopy (cm-IR-sSNOM), we image spin-polarized helical edge channels in ZrTe 5 at the nanoscale, revealing magnetic-field-induced brightening as a high-frequency electrodynamic signature of robust topological edge modes. Operating at 1.8 K and under a magnetic field of up to 5 T, we observe the emergence of edge-state polarizability at infrared frequencies that is notably resilient to the magnetic gaps that typically quench d.c. and microwave edge transport. Our results reveal a topological ‘two-lane’ spatial reorganization in which an external magnetic field induces a spin-population imbalance between counterpropagating edge modes. Favoured helical branches are confined against physical boundaries to activate a net infrared near-field contrast. This electrodynamic response scales linearly with the number of atomic layers, which confirms that individual layers in ZrTe 5 preserve their discrete quantum spin Hall identities. These findings may be useful for developing topological spintronic devices, as the magnetic infrared tunability of helical edge channels provides a pathway for low-loss nanoscale interconnects and high-speed information processing.
K5Tl3O crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are eight inequivalent K sites. In the first K site, K is bonded in a single-bond geometry to four equivalent Tl and one O atom. There are two shorter (3.80 Å) and two longer (3.95 Å) K–Tl bond lengths. The K–O bond length is 2.69 Å. In the second K site, K is bonded in a single-bond geometry to two Tl and one O atom. Both K–Tl bond lengths are 3.62 Å. The K–O bond length is 2.54 Å. In the third K site, K is bonded in a water-like geometry to two Tl and two equivalent O atoms. Both K–Tl bond lengths are 4.03 Å. There are one shorter (2.83 Å) and one longer (2.86 Å) K–O bond lengths. In the fourth K site, K is bonded in a single-bond geometry to four equivalent Tl and one O atom. There are two shorter (3.80 Å) and two longer (3.95 Å) K–Tl bond lengths. The K–O bond length is 2.69 Å. In the fifth K site, K is bonded in a single-bond geometry to four Tl and one O atom. There are two shorter (3.76 Å) and two longer (3.97 Å) K–Tl bond lengths. The K–O bond length is 2.66 Å. In the sixth K site, K is bonded in a single-bond geometry to four equivalent Tl and one O atom. There are two shorter (3.79 Å) and two longer (3.87 Å) K–Tl bond lengths. The K–O bond length is 2.52 Å. In the seventh K site, K is bonded in a single-bond geometry to four Tl and one O atom. There are two shorter (3.76 Å) and two longer (3.97 Å) K–Tl bond lengths. The K–O bond length is 2.66 Å. In the eighth K site, K is bonded in a single-bond geometry to four equivalent Tl and one O atom. There are two shorter (3.79 Å) and two longer (3.88 Å) K–Tl bond lengths. The K–O bond length is 2.52 Å. There are four inequivalent Tl sites. In the first Tl site, Tl is bonded in a 8-coordinate geometry to six K and two Tl atoms. Both Tl–Tl bond lengths are 3.19 Å. In the second Tl site, Tl is bonded in a 8-coordinate geometry to six K and two Tl atoms. Both Tl–Tl bond lengths are 3.11 Å. In the third Tl site, Tl is bonded in a distorted body-centered cubic geometry to four K and four Tl atoms. In the fourth Tl site, Tl is bonded in a distorted body-centered cubic geometry to four K and four Tl atoms. There are two inequivalent O sites. In the first O site, O is bonded to six K atoms to form edge-sharing OK6 octahedra. In the second O site, O is bonded in an octahedral geometry to six K atoms.
K is Copper structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. K is bonded to twelve equivalent K atoms to form a mixture of edge, corner, and face-sharing KK12 cuboctahedra. All K–K bond lengths are 4.71 Å.
We constrain a broad class of teleportation protocols using insights from locality. In the ``standard'' teleportation protocols we consider, all outcome-dependent unitaries are Pauli operators conditioned on linear functions of the measurement outcomes. We find that all such protocols involve preparing a ``resource state'' exhibiting symmetry-protected topological (SPT) order with Abelian protecting symmetry G k = ( Z 2 × Z 2 ) k . The k logical states are teleported between the edges of the chain by measuring the corresponding 2 k string order parameters in the bulk and applying outcome-dependent Paulis. Hence, this single class of nontrivial SPT states is both necessary and sufficient for the standard teleportation of k qubits. We illustrate this result with several examples, including the cluster state, variants thereof, and a nonstabilizer hypergraph state.
We propose and study a wave function describing an interacting three-dimensional fractional chiral hinge insulator (FCHI) constructed by Gutzwiller projection of two noninteracting second-order topological insulators with chiral hinge modes at half filling. We use large-scale variational Monte Carlo computations to characterize the model states via the entanglement entropy and charge-spin fluctuations. We show that the FCHI possesses fractional chiral hinge modes characterized by a central charge c = 1 and Luttinger parameter K = 1/2, like the edge modes of a Laughlin 1/2 state. The bulk and surface topology is characterized by the topological entanglement entropy (TEE) correction to the area law. While our computations indicate a vanishing bulk TEE, we show that the gapped surfaces host an unconventional two-dimensional topological phase. In a clear departure from the physics of a Laughlin 1/2 state, we find a TEE per surface compatible with (ln √2 )/2, half that of a Laughlin 1/2 state. This value cannot be obtained from topological quantum field theory for purely two-dimensional systems. For the sake of completeness, we also investigate the topological degeneracy.