Tunneling induced electron transfer between separated protons

We study electron transfer between two separated nuclei using local control theory. By conditioning the algorithm in a symmetric system formed by two protons, one can favored slow transfer processes, where tunneling is the main mechanism, achieving transfer efficiencies close to unity assuming fixed nuclei. The solution can be parametrized using sequences of pump and dump pi pulses, where the pump pulse is used to excite the electron to a highly excited state where the time for tunneling to the target nuclei is on the order of femtoseconds. The time delay must be chosen to allow for full population transfer via tunneling, and the dump pulse is chosen to remove energy from the state to avoid tunneling back to the original proton. Finally, we study the effect of the nuclear kinetic energy on the transfer efficiency. Even in the absence of relative motion between the protons, the spreading of the nuclear wave function is enough to reduce the yield of electronic transfer to less than one half.Comment: 7 pages, 8 figure

Implementing quantum gates on oriented optical isomers

Optical enantiomers are proposed to encode molecular two-qubit information processing. Using sequences of pairs of nonresonant optimally polarized pulses, different schemes to implement quantum gates, and to prepare entangled states, are described. We discuss the role of the entanglement phase and the robustness of the pulse sequences which depend on the area theorem. Finally, possible scenarios to generalize the schemes to n-qubit systems are suggested. © 2004 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70017/2/JCPSA6-120-23-10955-1.pd

Two-qubit quantum gates with minimal pulse sequences

Working with trapped atoms at close distance to each other, we show that one can implement entangling gates based on non-independent qubits using a single pulse per qubit, or a single structured pulse. The optimal parameters depend on approximate solutions of Diophantine equations, causing the fidelity to never be exactly perfect, even under ideal conditions, although the errors can be made arbitrarily smaller at the cost of stronger fields. We fully characterize the mechanism by which the gates operate, and show that the main source of error in realistic implementations comes from fluctuations in the peak intensity, which especially damages the fidelity of the gates that use stronger fields. Working with two-pulse sequences, instead of one, enables the use of a plethora of mechanisms and a broad range of optimal parameters to choose from, to achieve high-fidelity gates.Comment: 10 pages, 7 figure

Ultrafast coherent control of giant oscillating molecular dipoles in the presence of static electric fields

The following article appeared in Journal of Chemical Physic 139.8 (2013): 084306 and may be found at http://scitation.aip.org/content/aip/journal/jcp/139/8/10.1063/1.4818878We propose a scheme to generate electric dipole moments in homonuclear molecular cations by creating, with an ultrashort pump pulse, a quantum superposition of vibrational states on electronic states strongly perturbed by very strong static electric fields. By field-induced molecular stabilization, the dipoles can reach values as large as 50 Debyes and oscillate on a time-scale comparable to that of the slow vibrational motion. We show that both the electric field and the pump pulse parameters can be used to control the amplitude and period of the oscillation, while preventing the molecule from ionizing or dissociatingThis work was supported by the NRF grant funded by the Korean government (2007-0056343 and 2012M3C1A6035358), the Basic Science Research program funded by MEST (2010-0005143), the Advanced Grant of the European Research Council XCHEM 290853, the European grant MC-RG ATTOTREND, the European COST Actions CM0702 (CUSPFEL) and CM1204 (XLIC), the European ITN CORINF, the MICINN Project Nos. CTQ2012-36184, FIS2010-15127, and CSD 2007-00010 (Spain), and the ERA-Chemistry project PIM2010EEC-0075

Idiopathic adulthood ductopenia: long-term follow-up after liver transplantation

In 1988, Ludwig et al proposed the term idiopathic adulthood ductopenia (IAD) for the condition of chronic cholestatic liver disease associated with loss of intrahepatic bile ducts of unknown etiology with clinical onset in adulthood (1). In recent years, several cases of idiopathic biliary ductopenia in adulthood have been described. This disease is severe in most cases and can progress to cirrhosis. For progressive IAD, orthotopic liver transplantation (OLT) has been the only successful treatment. There are only a few cases reported of OLT for IAD and no information is available about the prognosis of these patients in the long term after OLT. In the present report, we describe the long-term follow-up after OLT in one patient fulfilling IAD criteria