Superconducting Cavity Electromechanics: The Realization of an Acoustic Frequency Comb at Microwave Frequencies.

We present a nonlinear multimode superconducting electroacoustic system, where the interplay between superconducting kinetic inductance and piezoelectric strong coupling establishes an effective Kerr nonlinearity among multiple acoustic modes at 10 GHz that could hardly be achieved via intrinsic mechanical nonlinearity. By exciting this multimode Kerr system with a single microwave tone, we further demonstrate a coherent electroacoustic frequency comb and provide theoretical understanding of multimode nonlinear interaction in the superstrong coupling limit. This nonlinear superconducting electroacoustic system sheds light on the active control of multimode resonator systems and offers an enabling platform for the dynamic study of microcombs at microwave frequencies.

Photonic integration of Er3+:Y2SiO5 with thin-film lithium niobate by flip chip bonding.

Rare earth ions are known as promising candidates for building quantum light-matter interface. However, tunable photonic cavity access to rare earth ions in their desired host crystal remains challenging. Here, we demonstrate the integration of erbium doped yttrium orthosilicate (Er3+:Y2SiO5) with thin-film lithium niobate photonic circuit by plasma-activated direct flip chip bonding. Resonant coupling to erbium ions is realized by on-chip electro-optically tuned high Q lithium niobate micro-ring resonators. Fluorescence and absorption of erbium ions at 1536.48 nm are measured in the waveguides, while the collective ion-cavity cooperativity with micro-ring resonators is assessed to be 0.36. This work presents a versatile scheme for future rare earth ion integrated quantum devices.

Mitigating photorefractive effect in thin-film lithium niobate microring resonators.

Thin-film lithium niobate is an attractive integrated photonics platform due to its low optical loss and favorable optical nonlinear and electro-optic properties. However, in applications such as second harmonic generation, frequency comb generation, and microwave-to-optics conversion, the device performance is strongly impeded by the photorefractive effect inherent in thin-film lithium niobate. In this paper, we show that the dielectric cladding on a lithium niobate microring resonator has a significant influence on the photorefractive effect. By removing the dielectric cladding layer, the photorefractive effect in lithium niobate ring resonators can be effectively mitigated. Our work presents a reliable approach to control the photorefractive effect on thin-film lithium niobate and will further advance the performance of integrated classical and quantum photonic devices based on thin-film lithium niobate.

Stable tuning of photorefractive microcavities using an auxiliary laser.

Cavity nonlinear optics enables intriguing physical phenomena to occur at micro- or nano-scales with modest input powers. While this enhances capabilities in applications such as comb generation, frequency conversion, and quantum optics, undesired nonlinear effects including photorefraction and thermal bistability are exacerbated. In this Letter, we propose and demonstrate a highly effective method of achieving cavity stabilization using an auxiliary laser for controlling photorefraction in a z-cut periodically poled lithium niobate (LN) microcavity system. Our numerical study accurately models the photorefractive effect under high input powers, guiding future analyses and development of LN microcavity systems.

Photorefraction-induced Bragg scattering in cryogenic lithium niobate ring resonators.

We report intracavity Bragg scattering induced by the photorefractive (PR) effect in high-Q lithium niobate ring resonators at cryogenic temperatures. We show that when a cavity mode is strongly excited, the PR effect imprints a long-lived periodic space-charge field. This residual field in turn creates a refractive index modulation pattern that dramatically enhances the back scattering of an incoming probe light, and results in selective and reconfigurable mode splittings. This PR-induced Bragg scattering effect, despite being undesired for many applications, could be utilized to enable optically programmable photonic components.

Quantum electronic control on chemical activation of methane by collision with spin-orbit state selected vanadium cation.

By coupling a newly developed quantum-electronic-state-selected supersonically cooled vanadium cation (V+) beam source with a double quadrupole-double octopole (DQDO) ion-molecule reaction apparatus, we have investigated detailed absolute integral cross sections (σ's) for the reactions, V+[a5DJ (J = 0, 2), a5FJ (J = 1, 2), and a3FJ (J = 2, 3)] + CH4, covering the center-of-mass collision energy range of Ecm = 0.1-10.0 eV. Three product channels, VH+ + CH3, VCH2+ + H2, and VCH3+ + H, are unambiguously identified based on Ecm-threshold measurements. No J-dependences for the σ curves (σ versus Ecm plots) of individual electronic states are discernible, which may indicate that the spin-orbit coupling is weak and has little effect on chemical reactivity. For all three product channels, the maximum σ values for the triplet a3FJ state [σ(a3FJ)] are found to be more than ten times larger than those for the quintet σ(a5DJ) and σ(a5FJ) states, showing that a reaction mechanism favoring the conservation of total electron spin. Without performing a detailed theoretical study, we have tentatively interpreted that a weak quintet-to-triplet spin crossing is operative for the activation reaction. The σ(a5D0, a5F1, and a3F2) measurements for the VH+, VCH2+, and VCH3+ product ion channels along with accounting of the kinetic energy distribution due to the thermal broadening effect for CH4 have allowed the determination of the 0 K bond dissociation energies: D0(V+-H) = 2.02 (0.05) eV, D0(V+-CH2) = 3.40 (0.07) eV, and D0(V+-CH3) = 2.07 (0.09) eV. Detailed branching ratios of product ion channels for the titled reaction have also been reported. Excellent simulations of the σ curves obtained previously for V+ generated by surface ionization at 1800-2200 K can be achieved by the linear combination of the σ(a5DJ, a5FJ, and a3FJ) curves weighted by the corresponding Boltzmann populations of the electronic states. In addition to serving as a strong validation of the thermal equilibrium assumption for the populations of the V+ electronic states in the hot filament ionization source, the agreement between these results also confirmed that the V+(a5DJ, a5FJ, and a3FJ) states prepared in this experiment are in single spin-orbit states with 100% purity.

Photonic Dissipation Control for Kerr Soliton Generation in Strongly Raman-Active Media.

Microcavity solitons enable miniaturized coherent frequency comb sources. However, the formation of microcavity solitons can be disrupted by stimulated Raman scattering, particularly in the emerging crystalline microcomb materials with high Raman gain. Here, we propose and implement dissipation control-tailoring the energy dissipation of selected cavity modes-to purposely raise or lower the threshold of Raman lasing in a strongly Raman-active lithium niobate microring resonator and realize on-demand soliton mode locking or Raman lasing. Numerical simulations are carried out to confirm our analyses and agree well with experiment results. Our work demonstrates an effective approach to address strong stimulated Raman scattering for microcavity soliton generation.

Radiative Cooling of a Superconducting Resonator.

Cooling microwave resonators to near the quantum ground state, crucial for their operation in the quantum regime, is typically achieved by direct device refrigeration to a few tens of millikelvin. However, in quantum experiments that require high operation power such as microwave-to-optics quantum transduction, it is desirable to operate at higher temperatures with non-negligible environmental thermal excitations, where larger cooling power is available. In this Letter, we present a radiative cooling protocol to prepare a superconducting microwave mode near its quantum ground state in spite of warm environment temperatures for the resonator. In this proof-of-concept experiment, the mode occupancy of a 10 GHz superconducting resonator thermally anchored at 1.02 K is reduced to 0.44±0.05 from 1.56 by radiatively coupling to a 70 mK cold load. This radiative cooling scheme allows high-operation-power microwave experiments to work in the quantum regime, and opens possibilities for routing microwave quantum states to elevated temperatures.

Chemical Activation of Water Molecule by Collision with Spin-Orbit-State-Selected Vanadium Cation: Quantum-Electronic-State Control of Chemical Reactivity.

We have obtained absolute integral cross sections (σ's) for the reactions of spin-orbit-state-selected vanadium cations, V+[a5DJ(J = 0, 2), a5FJ(J = 1, 2), and a3FJ(J = 2, 3)], with a water molecule (H2O) in the center-of-mass collision energy range Ecm = 0.1-10.0 eV. On the basis of these state-selected σ curves (σ versus Ecm plots) observed, three reaction product channels, VO+ + H2, VH+ + OH, and VOH+ + H, from the V+ + H2O reaction are unambiguously identified. Contrary to the previous guided ion beam study of the V+(a5DJ) + D2O reaction, we have observed the formation of the VO+ + H2 channel from the V+(a5DJ) + H2O ground reactant state at low Ecm's (<3.0 eV). No spin-orbit J-state dependences for the σ curves of individual electronic states are discernible, indicating that spin-orbit interactions are weak with little effect on chemical reactivity of the titled reaction. For the three product channels identified, the triplet σ(a3FJ) values are overwhelmingly higher than the quintet σ(a5DJ) and σ(a5FJ) values, showing that the reaction is governed by a "weak quintet-triplet spin crossing" mechanism, favoring the conservation of total electron spins. The σ curves for exothermic product channels are found to exhibit a rapid decreasing profile as Ecm is increased, an observation consistent with the prediction of the charge-dipole and induced-dipole orbiting model. This experiment shows that the V+ + H2O reaction can be controlled effectively to produce predominantly the VO+ + H2 channel via the V+(a3FJ) + H2O reaction at low Ecm's (≤0.1 eV) and that the ion-molecule reaction dynamics can be altered readily by selecting the electronic state of V+ cation. On the basis of the measured Ecm thresholds for the σ(a5DJ, a5FJ, and a3FJ: VH+) and σ(a5DJ, a5FJ, and a3FJ: VOH+) curves, we have deduced upper bound values of 2.6 ± 0.2 and 4.3 ± 0.3 eV for the 0 K bond dissociation energies, D0(V+-H) and D0(V+-OH), respectively. After correcting for the kinetic energy distribution resulting from the Doppler broadening effect of the H2O molecule, we obtain D0(V+-H) = 2.2 ± 0.2 eV and D0(V+-OH) = 4.0 ± 0.3 eV, which are in agreement with D0 determinations obtained by σ curve simulations.

Octave-spanning supercontinuum generation in nanoscale lithium niobate waveguides.

We demonstrate octave-spanning supercontinuum generation in unpoled lithium niobate waveguides, which are engineered to possess anomalous dispersion and pumped by a turn-key femtosecond laser centered at 1560 nm. Tunable dispersive waves and strong phase-matched second-harmonic generation are both observed by controlling the widths of the waveguides. The major features of the experimental spectra are reproduced by numerical modeling of the generalized nonlinear Schrödinger equation, which can be used to guide waveguide designs for tailoring the supercontinuum spectrum. Our results identify a path to a simple and integrable supercontinuum source in lithium niobate nanophotonic platform and will enable new capabilities in precision frequency metrology.

Soliton microcomb generation at 2 µm in z-cut lithium niobate microring resonators.

Chip-based soliton frequency combs have been demonstrated on various material platforms, offering broadband, mutually coherent, and equally spaced frequency lines desired for many applications. Lithium niobate (LN), possessing both second- and third-order optical nonlinearities, as well as integrability on insulating substrates, has emerged as a novel source for microcomb generation and controlling. Here we demonstrate mode-locked soliton microcombs generated around 2 µm in a high-Q z-cut LN microring resonator. The intracavity photorefractive effect is found to be still dominant over the thermal effect in the 2 µm region, which facilitates direct accessing soliton states in the red-detuned regime, as reported in the telecom band. We also find that intracavity stimulated Raman scattering is greatly suppressed when moving the pump wavelength from the telecom band to 2 µm, thus alleviating Raman-Kerr comb competition. This Letter expands mode-locked LN microcombs to 2 µm, and could enable a variety of potential applications based on LN nanophotonic platform.

Quantum state control on the chemical reactivity of a transition metal vanadium cation in carbon dioxide activation.

By combining a newly developed two-color laser pulsed field ionization-photoion (PFI-PI) source and a double-quadrupole-double-octopole (DQDO) mass spectrometer, we investigated the integral cross sections (σs) of the vanadium cation (V+) toward the activation of CO2 in the center-of-mass kinetic energy (Ecm) range from 0.1 to 10.0 eV. Here, V+ was prepared in single spin-orbit levels of its lowest electronic states, a5DJ (J = 0-4), a5FJ (J = 1-5), and a3FJ (J = 2-4), with well-defined kinetic energies. For both product channels VO+ + CO and VCO+ + O identified, V+(a3F2,3) is found to be greatly more reactive than V+(a5D0,2) and V+(a5F1,2), suggesting that the V+ + CO2 reaction system mainly proceeds via a "weak quintet-to-triplet spin-crossing" mechanism favoring the conservation of total electron spins. In addition, no J-state dependence was observed. The distinctive structures of the quantum electronic state selected integral cross sections observed as a function of Ecm and the electronic state of the V+ ion indicate that the difference in the chemical reactivity of the title reaction originated from the quantum-state instead of energy effects. Furthermore, this work suggests that the selection of the quantum electronic states a3FJ (J = 2-4) of the transition metal V+ ion can greatly enhance the efficiency of CO2 activation.

Quantum Spin-Orbit Electronic State Selection of Atomic Transition Metal Vanadium Cation for Chemical Reactivity Studies.

By combining a pulsed laser ablation vanadium atom (V) beam source with the two-color laser sequential electric field pulse scheme for pulse field ionization-photoion (PFI-PI) detection, we have developed a quantum spin-orbit state selected transition metal ion source for ion-molecule reaction studies. As a demonstration, we show that the V+ ion can be prepared in the single spin-orbit levels of its three lowest quantum electronic states, V+[a5DJ ( J = 0-4), a5FJ ( J = 1-5), and a3FJ ( J = 2-4)], achieving laboratory kinetic energy ( Elab) resolutions of ≤0.2 eV. The precursor V atom beam is first excited to high- n Rydberg states by resonance-enhanced visible-ultraviolet laser photoexcitation via the V*[3d3(4F) 4s4p (3P°)] neutral intermediate state. The total photon energy is tuned in the regions from 54 380 to 63 520 cm-1 to cover the photoionization energies for the formation of these spin-orbit states. Sharp Rydberg transitions converging to the V+[a5DJ ( J = 1 and 2)] spin-orbit levels are identified in the respective PFI-PI spectra for the V+[a5DJ ( J = 0 and 1)] states. The analysis of these Rydberg members observed yields an ionization energy of 54 412.65 ± 0.15 cm-1 for V atom, which is in excellent accord with the literature value of 54 413 ± 1 cm-1 eV. In order to understand the profile for the PFI-PI spectrum of V+ ion observed and thus obtain reliable Stark shift corrections by using the sequential PFI-PI detection scheme, we have also examined the PFI-PI spectrum for Ar+(2P3/2) in detail by varying the retarding as well as the PFI electric field pulses.

Chemical Activation of a Deuterium Molecule by Collision with a Quantum Electronic State-Selected Vanadium Cation.

By combining a newly developed spin-orbit electronic state-selected ion source for vanadium cations (V+) with a double quadrupole-double octopole mass spectrometer, we have investigated in detail the chemical reactivity or integral cross sections (σ's) for the reactions of V+[a5DJ (J = 0, 1), a5FJ (J = 1, 2), and a3FJ (J = 2, 3)] ion with a deuterium molecule (D2). The vanadium deuteride ion (VD+) is identified to be the only product ion formed in the center-of-mass collision energies of Ecm = 0.1-10.0 V. No J dependence for the σ's is discernible for individual electronic states, indicating that the spin-orbit coupling is weak and has little effect on the chemical reactivity of the titled reaction. The maximum σ value for the V+(a3FJ) state [σ(a3FJ)] is about 7 and 70 times larger than those for σ(a5DJ) and σ(a5FJ), respectively, showing that the triplet V+(a3FJ) state is dominantly more reactive than the quintet states. Although the V+(a5FJ) state is 0.3 eV higher than the V+(a5DJ) ground state, the chemical reactivity of the V+(a5FJ) state is significantly lower than that of the V+(a5DJ) state, clearly indicating that the differences in chemical activity observed are due to quantum electronic states rather than energy effects. The Ecm thresholds determined for σ(a5DJ), σ(a5FJ), and σ(a3FJ) are consistent with the respective energetics for the formation of VD+ from the V+(a5DJ, a5FJ, and a3FJ) + D2 reactions. The analysis of Ecm threshold measurements yields a bond energy of D0(V+-D) = 2.5 ± 0.2 eV, suggesting that the previously reported values are too low by up to 0.4 eV. The large differences for σ(a5DJ, a5FJ, and a3FJ) observed here indicate that the activation of D2 by a V+ ion can be efficiently controlled by selecting the V+ electronic state as well as the Ecm. The quantum state-selected σ values presented here can also serve as experimental benchmarks for first-principles theoretical reaction dynamics calculations.

Homogeneous ice nucleation rates and crystallization kinetics in transiently-heated, supercooled water films from 188 K to 230 K.

The crystallization kinetics of transiently heated, nanoscale water films were investigated for 188 K < Tpulse < 230 K, where Tpulse is the maximum temperature obtained during a heat pulse. The water films, which had thicknesses ranging from approximately 15-30 nm, were adsorbed on a Pt(111) single crystal and heated with ∼10 ns laser pulses, which produced heating and cooling rates of ∼109-1010 K/s in the adsorbed water films. Because the ice growth rates have been measured independently, the ice nucleation rates could be determined by modeling the observed crystallization kinetics. The experiments show that the nucleation rate goes through a maximum at T = 216 K ± 4 K, and the rate at the maximum is 1029±1 m-3 s-1. The maximum nucleation rate reported here for flat, thin water films is consistent with recent measurements of the nucleation rate in nanometer-sized water drops at comparable temperatures. However, the nucleation rate drops rapidly at lower temperatures, which is different from the nearly temperature-independent rates observed for the nanometer-sized drops. At T ∼ 189 K, the nucleation rate for the current experiments is a factor of ∼104-5 smaller than the rate at the maximum. The nucleation rate also decreases for Tpulse > 220 K, but the transiently heated water films are not very sensitive to the smaller nucleation rates at higher temperatures. The crystallization kinetics are consistent with a "classical" nucleation and growth mechanism indicating that there is an energetic barrier for deeply supercooled water to convert to ice.

Growth rate of crystalline ice and the diffusivity of supercooled water from 126 to 262 K.

Understanding deeply supercooled water is key to unraveling many of water's anomalous properties. However, developing this understanding has proven difficult due to rapid and uncontrolled crystallization. Using a pulsed-laser-heating technique, we measure the growth rate of crystalline ice, G(T), for 180 K < T < 262 K, that is, deep within water's "no man's land" in ultrahigh-vacuum conditions. Isothermal measurements of G(T) are also made for 126 K ≤ T ≤ 151 K. The self-diffusion of supercooled liquid water, D(T), is obtained from G(T) using the Wilson-Frenkel model of crystal growth. For T > 237 K and P ∼ 10-8 Pa, G(T) and D(T) have super-Arrhenius ("fragile") temperature dependences, but both cross over to Arrhenius ("strong") behavior with a large activation energy in no man's land. The fact that G(T) and D(T) are smoothly varying rules out the hypothesis that liquid water's properties have a singularity at or near 228 K at ambient pressures. However, the results are consistent with a previous prediction for D(T) that assumed no thermodynamic transitions occur in no man's land.

Visualizing Mie Resonances in Low-Index Dielectric Nanoparticles.

Resonant light scattering by metallic and high-index dielectric nanoparticles has received enormous attention and found many great applications. However, low-index dielectric nanoparticles typically do not show resonant scattering behaviors due to poor light confinement caused by small index contrast. This Letter describes a simple and effective approach to drastically enhance the resonance effect of the low-index particles by partial metal dressing. Mie resonances of low-index nanoparticles can now be easily visualized by scattered light. This scattering peak depends on sphere size and has a reasonable linewidth. A size difference as small as 8 nm was resolved by a peak shift or even by color change. The scattering peak is attributed to the enhanced TE_{11} Mie resonance of the low-index nanospheres. The metal dress not only provides a high-reflection boundary, but also functions as an antenna to couple the confined light power to the far field, leading to scattering maxima in the spectra. Additionally, the enhanced TE_{11} Mie resonance in low-index nanoparticles features a considerable magnetic response due to the strong circulating displacement currents induced by the intensified E field despite of a low permittivity (hence low index) of the particles. The enhanced Mie resonances could be used to sense minute changes in size or refractive index of low-index nanoparticles and benefit a wide range of applications.

Quantum-State-Selected Integral Cross Sections and Branching Ratios for the Ion-Molecule Reaction of N2+(X2Σg+: ν+ = 0-2) + C2H4 in the Collision Energy Range of 0.05-10.00 eV.

By implementing a vacuum ultraviolet laser-pulsed field ionization-photoion ion source with a double quadrupole-double octopole ion guide mass filter, we have obtained detailed quantum-vibrational-state-selected integral cross sections σν+, ν+ = 0-2, for the ion-molecule reaction of N2+(X2Σg+: ν+ = 0-2) + C2H4 in the center-of-mass kinetic energy range of Ecm = 0.05-10.00 eV. Three primary product channels corresponding to the formation of C2H3+, C2H2+, and N2H+ ions are identified with their σν+ values in the order of σν+(C2H3+) > σν+(C2H2+) > σν+(N2H+). The minor σν+(N2H+) channel is strongly inhibited by Ecm and observed only at Ecm < 0.70 eV. The high σν+(C2H3+) and σν+(C2H2+) values indicate that C2H3+ and C2H2+ product ions are formed by prompt dissociation of internally excited C2H4+ (C2H4+*) intermediates produced via the near-energy-resonance charge-transfer mechanism. The σν+(C2H3+) and σν+(C2H2+) are found to drop only mildly or stay nearly constant as a function of Ecm in the range of 0.05-6.00 eV. This observation is contrary to the expectation of a steep decline for the σν+ value commonly observed for an exothermic reaction pathway as Ecm is increased. Significant vibrational enhancement is observed for the σν+(C2H3+) and σν+(C2H2+) at ν+ = 2 and in the Ecm range of ∼0.20-7.00 eV. The branching ratios σν+(C2H3+):σν+(C2H2+):σν+(N2H+) are also determined with high precision by measuring the intensities of product C2H3+, C2H2+, and N2H+ ions simultaneously at fixed Ecm values. The σν+ and branching ratio values reported here are useful contributions to the database needed for realistic modeling of the chemical compositions and evolutions of planetary atmospheres, such as the ionosphere of Titian. The quantum-state-selective results can also serve as experimental benchmarks for theoretical calculations on fundamental chemical reaction dynamics.

Coating Polymeric Carbon Nitride Photoanodes on Conductive Y:ZnO Nanorod Arrays for Overall Water Splitting.

Polymeric carbon nitride (PCN) photosensitizers are proposed replacements for their inorganic counterparts in solar-to-fuel conversion via photoelectrochemical water splitting. However, intense charge recombination, primarily because of surface defects, limits the use of PCN in PEC systems. Now, photoanodes are designed by coating PCN films onto highly conductive yttrium-doped zinc oxide (Y:ZnO) nanorods (NRs) serving as charge collectors. The generation of charge carriers can therefore be promoted by this type II alignment. The charge collectors would be kept nearby for charge separation and transport to be used in the interfacial redox reactions. The photocurrent density of the polymer electrode is improved to 0.4 mA cm-2 at 1.23 V vs. the reversible hydrogen electrode in a Na2 SO4 electrolyte solution under AM 1.5 illumination. The result reveals a more than 50-fold enhancement over the PCN films achieved by powder; the efficiency can be preserved at 95 % for 160 minutes.

Isotopic and quantum-rovibrational-state effects for the ion-molecule reaction in the collision energy range of 0.03-10.00 eV.

We report detailed quantum-rovibrational-state-selected integral cross sections for the formation of H3O+via H-transfer (σHT) and H2DO+via D-transfer (σDT) from the reaction in the center-of-mass collision energy (Ecm) range of 0.03-10.00 eV, where (vvv) = (000), (100), and (020) and . The Ecm inhibition and rotational enhancement observed for these reactions at Ecm < 0.5 eV are generally consistent with those reported previously for H2O+ + H2(D2) reactions. However, in contrast to the vibrational inhibition observed for the latter reactions at low Ecm < 0.5 eV, both the σHT and σDT for the H2O+ + HD reaction are found to be enhanced by (100) vibrational excitation, which is not predicted by the current state-of-the-art theoretical dynamics calculations. Furthermore, the (100) vibrational enhancement for the H2O+ + HD reaction is observed in the full Ecm range of 0.03-10.00 eV. The fact that vibrational enhancement is only observed for the reaction of H2O+ + HD, and not for H2O+ + H2(D2) reactions suggests that the asymmetry of HD may play a role in the reaction dynamics. In addition to the strong isotopic effect favoring the σHT channel of the H2O+ + HD reaction at low Ecm < 0.5 eV, competition between the σHT and σDT of the H2O+ + HD reaction is also observed at Ecm = 0.3-10.0 eV. The present state-selected study of the H2O+ + HD reaction, along with the previous studies of the H2O+ + H2(D2) reactions, clearly shows that the chemical reactivity of H2O+ toward H2 (HD, D2) depends not only on Ecm, but also on the rotational and vibrational states of H2O+(X2B1). The detailed σHT and σDT values obtained here with single rovibrational-state selections of the reactant H2O+ are expected to be valuable benchmarks for state-of-the-art theoretical calculations on the chemical dynamics of the title reaction.