Effect of uniaxial stress on substitutional Ni in ZnO

The influence of uniaxial stress on the electronic T13(F)→T23(F) transitions of Ni2+ (d8) in ZnO at 4216, 4240, and 4247 cm-1 is studied. It is shown that the split pattern and polarized properties of IR absorption lines are consistent with a dynamic Jahn-Teller effect in the T23(F) state of the defect. © 2013 Elsevier Ltd

Identification of Fe3+-Li+ complexes in ZnO by means of high-frequency EPR/ENDOR spectroscopy

Theoretical prediction of a high Curie temperature in ZnO doped with Mn, Fe, and other transition metals has stimulated the investigation of these materials by many research groups. Although charge-compensated Fe3+ centers in ZnO:Fe have been observed by means of EPR and have been known for decades, conclusions on the chemical nature of these defects are still contradictory. Originally, these centers were treated as Fe3+-Li + complexes with both ions occupying adjacent cationic sites. Recently, however, the centers were interpreted as a substitutional Fe 3+ ion with a vacancy at an adjacent zinc or oxygen site (Fe-V Zn or Fe-VO). In order to determine the chemical nature of the impurity associated with Fe3+, electron-nuclear double resonance (ENDOR) spectroscopy was used. ENDOR measurements reveal NMR transitions corresponding to nuclei with g-factor gN = 2.171 and spin I = 3/2. This unambiguously shows presence of Li as a charge compensator and also resolves contradictions with the theoretical prediction of the Fe-VO formation energy. The electric field gradients at the 7Li nuclei (within the Fe3+-Li+ complexes) were estimated to be significantly lower than the gradient at undistorted Zn sites. © 2013 Elsevier Inc. All rights reserved

Synthesis and Optimization of Reversible Circuits - A Survey

Reversible logic circuits have been historically motivated by theoretical research in low-power electronics as well as practical improvement of bit-manipulation transforms in cryptography and computer graphics. Recently, reversible circuits have attracted interest as components of quantum algorithms, as well as in photonic and nano-computing technologies where some switching devices offer no signal gain. Research in generating reversible logic distinguishes between circuit synthesis, post-synthesis optimization, and technology mapping. In this survey, we review algorithmic paradigms --- search-based, cycle-based, transformation-based, and BDD-based --- as well as specific algorithms for reversible synthesis, both exact and heuristic. We conclude the survey by outlining key open challenges in synthesis of reversible and quantum logic, as well as most common misconceptions.Comment: 34 pages, 15 figures, 2 table

Effect of quantum confinement and influence of extra charge on the electric field gradient in ZnO

By means of electron-nuclear double resonance (ENDOR), it is shown that the Al impurity, which acts as a shallow donor in ZnO, leads to a significant reduction of the electric field gradient in ZnO single crystals. In ZnO quantum dots, however, the gradient on the Al sites remains virtually unchanged. When the Zn 2+ ion is substituted by Mn 2+ in a ZnO single crystal, the electric field gradient slightly increases (by about 20%). Therefore, the Mn 2+ ions can be used as probes to monitor the electric field gradients in ZnO crystals. © 2012 Pleiades Publishing, Ltd

Identification of shallow Al donors in ZnO

A combined magnetic resonance, photoluminescence, photoconductivity, and Raman scattering study of ZnO is presented. Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) spectroscopy identify substitutional Al as a binding core of a shallow, effective-mass-like donor in ZnO. Based on the correlation between the EPR and photoluminescence data it is shown that recombination of an exciton bound to Al gives rise to the 3360.7meV photoluminescence line (I 6). A 1s→ 2p donor transition at 316cm -1 is detected in photoconductivity and Raman spectra. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Simulating chemistry efficiently on fault-tolerant quantum computers

Quantum computers can in principle simulate quantum physics exponentially faster than their classical counterparts, but some technical hurdles remain. Here we consider methods to make proposed chemical simulation algorithms computationally fast on fault-tolerant quantum computers in the circuit model. Fault tolerance constrains the choice of available gates, so that arbitrary gates required for a simulation algorithm must be constructed from sequences of fundamental operations. We examine techniques for constructing arbitrary gates which perform substantially faster than circuits based on the conventional Solovay-Kitaev algorithm [C.M. Dawson and M.A. Nielsen, \emph{Quantum Inf. Comput.}, \textbf{6}:81, 2006]. For a given approximation error $\epsilon$, arbitrary single-qubit gates can be produced fault-tolerantly and using a limited set of gates in time which is $O(\log \epsilon)$ or $O(\log \log \epsilon)$; with sufficient parallel preparation of ancillas, constant average depth is possible using a method we call programmable ancilla rotations. Moreover, we construct and analyze efficient implementations of first- and second-quantized simulation algorithms using the fault-tolerant arbitrary gates and other techniques, such as implementing various subroutines in constant time. A specific example we analyze is the ground-state energy calculation for Lithium hydride.Comment: 33 pages, 18 figure

Conditional Disclosure of Secrets: Amplification, Closure, Amortization, Lower-bounds, and Separations

In the \emph{conditional disclosure of secrets} problem (Gertner et al., J. Comput. Syst. Sci., 2000) Alice and Bob, who hold inputs $x$ and $y$ respectively, wish to release a common secret $s$ to Carol (who knows both $x$ and $y$) if only if the input $(x,y)$ satisfies some predefined predicate $f$. Alice and Bob are allowed to send a single message to Carol which may depend on their inputs and some joint randomness and the goal is to minimize the communication complexity while providing information-theoretic security. Following Gay, Kerenidis, and Wee (Crypto 2015), we study the communication complexity of CDS protocols and derive the following positive and negative results. 1. *Closure* A CDS for $f$ can be turned into a CDS for its complement $\bar{f}$ with only a minor blow-up in complexity. More generally, for a (possibly non-monotone) predicate $h$, we obtain a CDS for $h(f_1,\ldots,f_m)$ whose cost is essentially linear in the formula size of $h$ and polynomial in the CDS complexity of $f_i$. 2. *Amplification* It is possible to reduce the privacy and correctness error of a CDS from constant to $2^{-k}$ with a multiplicative overhead of $O(k)$. Moreover, this overhead can be amortized over $k$-bit secrets. 3. *Amortization* Every predicate $f$ over $n$-bit inputs admits a CDS for multi-bit secrets whose amortized communication complexity per secret bit grows linearly with the input length $n$ for sufficiently long secrets. In contrast, the best known upper-bound for single-bit secrets is exponential in $n$. 4. *Lower-bounds* There exists a (non-explicit) predicate $f$ over $n$-bit inputs for which any perfect (single-bit) CDS requires communication of at least $\Omega(n)$. This is an exponential improvement over the previously known $\Omega(\log n)$ lower-bound. 5. *Separations* There exists an (explicit) predicate whose CDS complexity is exponentially smaller than its randomized communication complexity. This matches a lower-bound of Gay et. al., and, combined with another result of theirs, yields an exponential separation between the communication complexity of linear CDS and non-linear CDS. This is the first provable gap between the communication complexity of linear CDS (which captures most known protocols) and non-linear CDS

Quantum Multicollision-Finding Algorithm

The current paper presents a new quantum algorithm for finding multicollisions, often denoted by $l$-collisions, where an $l$-collision for a function is a set of $l$ distinct inputs having the same output value. Although it is fundamental in cryptography, the problem of finding multicollisions has not received much attention \emph{in a quantum setting}. The tight bound of quantum query complexity for finding $2$-collisions of random functions has been revealed to be $\Theta(N^{1/3})$, where $N$ is the size of a codomain. However, neither the lower nor upper bound is known for $l$-collisions. The paper first integrates the results from existing research to derive several new observations, e.g.~$l$-collisions can be generated only with $O(N^{1/2})$ quantum queries for a small constant $l$. Then a new quantum algorithm is proposed, which finds an $l$-collision of any function that has a domain size $l$ times larger than the codomain size. A rigorous proof is given to guarantee that the expected number of quantum queries is $O\left( N^{(3^{l-1}-1)/(2 \cdot 3^{l-1})} \right)$ for a small constant $l$, which matches the tight bound of $\Theta(N^{1/3})$ for $l=2$ and improves the known bounds, say, the above simple bound of $O(N^{1/2})$

Wolbachia endobacteria depletion by doxycycline as antifilarial therapy has macrofilaricidal activity in onchocerciasis: a randomized placebo-controlled study

In a randomized, placebo-controlled trial in Ghana, 67 onchocerciasis patients received 200-mg/day doxycycline for 4–6 weeks, followed by ivermectin (IVM) after 6 months. After 6–27 months, efficacy was evaluated by onchocercoma histology, PCR and microfilariae determination. Administration of doxycycline resulted in endobacteria depletion and female worm sterilization. The 6-week treatment was macrofilaricidal, with >60% of the female worms found dead, despite the presence of new, Wolbachia-containing worms acquired after the administration of doxycycline. Doxycycline may be developed as second-line drug for onchocerciasis, to be administered in areas without transmission, in foci with IVM resistance and in areas with Loa co-infections