Pulse retrieval and soliton formation in a non-standard scheme for dynamic electromagnetically induced transparency

We examine in detail an alternative method of retrieving the information written into an atomic ensemble of three-level atoms using electromagnetically induced transparency. We find that the behavior of the retrieved pulse is strongly influenced by the relative collective atom-light coupling strengths of the two relevant transitions. When the collective atom-light coupling strength for the retrieval beam is the stronger of the two transitions, regeneration of the stored pulse is possible. Otherwise, we show the retrieval process can lead to creation of soliton-like pulses.Comment: 11 figure

Comparative investigation of the coupled-tetrahedra quantum spin systems Cu2Te2O5X2, X=Cl, Br and Cu4Te5O12Cl4

We present a comparative study of the coupled-tetrahedra quantum spin systems Cu2Te2O5X2, X=Cl, Br (Cu-2252(X)) and the newly synthesized Cu4Te5O12Cl4 (Cu-45124(Cl)) based on ab initio Density Functional Theory calculations. The magnetic behavior of Cu-45124(Cl) with a phase transition to an ordered state at a lower critical temperature T$_c$=13.6K than in Cu-2252(Cl) (T$_c$=18K) can be well understood in terms of the modified interaction paths. We identify the relevant structural changes between the two systems and discuss the hypothetical behavior of the not yet synthesized Cu-45124(Br) with an ab initio relaxed structure using Car-Parrinello Molecular Dynamics.Comment: 2 pages, 1 figure; submitted to Proceedings of M2S-HTSC VIII, Dresden 200

Two-photon double ionization of neon using an intense attosecond pulse train

We present the first demonstration of two-photon double ionization of neon using an intense extreme ultraviolet (XUV) attosecond pulse train (APT) in a photon energy regime where both direct and sequential mechanisms are allowed. For an APT generated through high-order harmonic generation (HHG) in argon we achieve a total pulse energy close to 1 $\mu$J, a central energy of 35 eV and a total bandwidth of $\sim30$ eV. The APT is focused by broadband optics in a neon gas target to an intensity of $3\cdot10^{12}$W$\cdot$cm$^{-2}$. By tuning the photon energy across the threshold for the sequential process the double ionization signal can be turned on and off, indicating that the two-photon double ionization predominantly occurs through a sequential process. The demonstrated performance opens up possibilities for future XUV-XUV pump-probe experiments with attosecond temporal resolution in a photon energy range where it is possible to unravel the dynamics behind direct vs. sequential double ionization and the associated electron correlation effects

Full quantum solutions to the resonant four-wave mixing of two single-photon wave packets

We analyze both analytically and numerically the resonant four-wave mixing of two co-propagating single-photon wave packets. We present analytic expressions for the two-photon wave function and show that soliton-type quantum solutions exist which display a shape-preserving oscillatory exchange of excitations between the modes. Potential applications including quantum information processing are discussed.Comment: 7 pages, 3 figure

Longitudinal magnon in the tetrahedral spin system Cu2Te2O5Br2 near quantum criticality

We present a comprehensive study of the coupled tetrahedra-compound Cu2Te2O5Br2 by theory and experiments in external magnetic fields. We report the observation of a longitudinal magnon in Raman scattering in the ordered state close to quantum criticality. We show that the excited tetrahedral-singlet sets the energy scale for the magnetic ordering temperature T_N. This energy is determined experimentally. The ordering temperature T_N has an inverse-log dependence on the coupling parameters near quantum criticality

Patients' experiences of illness, operation and outcome with reference to gastro-oesophageal reflux disease.

Background. Describing the illness-story from a patient perspective could increase understanding of living with a chronic disease for health professionals and others, facilitate decision-making about treatment and enhance information about the outcome from a patient perspective. Aim. To illuminate patients' illness experiences of having a gastro-oesophageal reflux disease (GORD), going through surgery and the outcome. Methods. Twelve patients were interviewed 5 years after having had the operation; six patients had had fundoplication via laparoscopy and six via open surgery. Each patient was asked to talk openly about their experiences, thoughts, feelings and consequences of living with the illness, going through surgery and the period from surgery to the day of interview. A qualitative content analysis was performed concerning the context of the data and its meaning. Findings. Three central categories were identified and nine subcategories: living with GORD- symptoms of the disease affecting daily living, taking medicines, work, family and social life; concerns related to surgery- decision-making about the operation, influence by physicians; life after the operation- outcomes and consequences, side-effects and complications of the operation, sick leave, information and sharing experiences with future patients. All patients were free from symptoms of the illness after surgery independent of type of surgery, but side-effects from surgical treatment varied individually. Interviewees would have liked information concerning side-effects after surgery from previous patients. Conclusions. This study contributes to knowledge about patients' long-term suffering, their control of symptoms and how they have tried to cure themselves, but also about their concerns about surgery and the importance of surgical treatment to their quality of life. They wanted information about treatment, outcome and consequences, not only from a health care perspective but also from previous patients having had the same treatment

Attosecond pulse trains generated using two color laser fields

We investigate the spectral and temporal structure of high harmonic emission from argon exposed to an infrared laser field and its second harmonic. For a wide range of generating conditions, trains of attosecond pulses with only one pulse per infrared cycle are generated. The synchronization necessary for producing such trains ensures that they have a stable pulse-to-pulse carrier envelope phase, unlike trains generated from one color fields, which have two pulses per cycle and a pi phase shift between consecutive pulses. Our experiment extends the generation of phase stabilized few cycle pulses to the extreme ultraviolet regime