Influence of the nonradiative decay of qubits into a common channel on the transport properties of microwave photons

The influence of nonradiative damping of qubits on the microwave transport of photons propagating in a onedimensional microstrip line has been considered. Expressions for the transmission and reflection coefficients for two qubits have been obtained within the non-Hermitian Hamiltonian formalism. The indirect interaction between qubits caused by nonradiative decay into a common channel is explicitly taken into account in these expressions. It has been shown that this interaction leads to results significantly different from known results.     

Biologically Relevant Molecular Transducer with Increased Computing Power and Iterative Abilities

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Infrared and NMR Spectroscopic Fingerprints of the Asymmetric H7+O3 Complex in Solution

Infrared (IR) absorption in the 1000–3700 cm⁻¹ range and ¹H NMR spectroscopy reveal the existence of an asymmetric protonated water trimer, H₇⁺O_3, in acetonitrile. The core H₇⁺O₃ motif persists in larger protonated water clusters in acetonitrile up to at least 8 water molecules. Quantum mechanics/molecular mechanics (QM/MM) molecular dynamics (MD) simulations reveal irreversible proton transport promoted by propagating the asymmetric H₇⁺O₃ structure in solution. The QM/MM calculations allow for the successful simulation of the measured IR absorption spectra of H₇⁺O₃ in the OH stretch region, which reaffirms the assignment of the H₇⁺O₃ spectra to a hybrid-complex structure: a protonated water dimer strongly hydrogen-bonded to a third water molecule with the proton exchanging between the two possible shared-proton Zundel-like centers. The H₇⁺O₃ structure lends itself to promoting irreversible proton transport in presence of even one additional water molecule. We demonstrate how continuously evolving H₇⁺O₃ structures may support proton transport within larger water solvates.     

Quench dynamics and nonequilibrium phase diagram of the bose-hubbard model

We investigate the time evolution of correlations in the Bose-Hubbard model following a quench from the superfluid to the Mott insulator. For large values of the final interaction strength the system approaches a distinctly nonequilibrium steady state that bears strong memory of the initial conditions. In contrast, when the final interaction strength is comparable to the hopping, the correlations are rather well approximated by those at thermal equilibrium. The existence of two distinct nonequilibrium regimes is surprising given the nonintegrability of the Bose-Hubbard model. We relate this phenomenon to the role of quasiparticle interactions in the Mott insulator.     

Independent Generation and Time-Resolved Detection of 2′-Deoxyguanosin-N2-yl Radicals

Guanine radicals are important reactive intermediates in DNA damage. Hydroxyl radical (HO^.) has long been believed to react with 2′-deoxyguanosine (dG) generating 2′-deoxyguanosin-N1-yl radical (dG(N1-H)^.) via addition to the nucleobase π-system and subsequent dehydration. This basic tenet was challenged by an alternative mechanism, in which the major reaction of HO^. with dG was proposed to involve hydrogen atom abstraction from the N2-amine. The 2′-deoxyguanosin-N2-yl radical (dG(N2-H)^.) formed was proposed to rapidly tautomerize to dG(N1-H)^.. We report the first independent generation of dG(N2-H)^. in high yield via photolysis of 1 . dG(N2-H)^. is directly observed upon nanosecond laser flash photolysis (LFP) of 1 . The absorption spectrum of dG(N2-H)^. is corroborated by DFT studies, and anti- and syn-dG(N2-H)^. are resolved for the first time. The LFP experiments showed no evidence for tautomerization of dG(N2-H)^. to dG(N1-H)^. within hundreds of microseconds. This observation suggests that the generation of dG(N1-H)^. via dG(N2-H)^. following hydrogen atom abstraction from dG is unlikely to be a major pathway when HO^. reacts with dG.     

Decomposition of triacetone triperoxide is an entropic explosion

Both X-ray crystallography and electronic structure calculations using the cc-pVDZ basis set at the DFT B3LYP level were employed to study the explosive properties of triacetone triperoxide (TATP) and diacetone diperoxide (DADP). The thermal decomposition pathway of TATP was investigated by a series of calculations that identified transition states, intermediates, and the final products. Counterintuitively, these calculations predict that the explosion of TATP is not a thermochemically highly favored event. It rather involves entropy burst, which is the result of formation of one ozone and three acetone molecules from every molecule of TATP in the solid state.