Coherent and incoherent pumping of electrons in double quantum dots

We propose a new mode of operation of an electron pump consisting of two weakly coupled quantum dots connected to reservoirs. An electron can be transferred within the device at zero bias voltage when it is subjected to electromagnetic radiation, thereby exciting the double dot. The excited state can decay by transferring charge from one lead and to the other lead in one direction. Depending on the energies of the intermediate states in the pumping cycle, which are controlled by the gate voltages, this transport is either incoherent via well-known sequential tunneling processes, or coherent via a inelastic co-tunneling process. The latter novel mode of operation is possible only when interdot Coulomb charging is important. The D.C. transport through the system can be controlled by the frequency of the applied radiation. We concentrate on the resonant case, when the frequency matches the energy difference for exciting an electron from one dot into the other. The resonant peaks in the pumping current should be experimentally observable. We have developed a density matrix approach which describes the dynamics of the system on timescales much larger than the period of the applied irradiation. In contrast to previous works we additionally consider the case of slow modulation of the irradiation amplitude. Harmonic modulation produces additional sidepeaks in the photoresponse, and pulsed modulation can be used to resolve the Rabi frequency in the time-averaged current.Comment: 5 pages, 6 figures. This is an extension of cond-mat/9707310 "A coherent double-quantum-dot electron pump" This version has been accepted for publication in Phys. Rev. B. Changes: Added references. Corrected typos. Changed content mainly the introduction. Regime of device operation is now specified more precisely. A stability diagram has been added as a figure has been adde

Nonequilibrium stabilization of charge states in double quantum dots

We analyze the decoherence of charge states in double quantum dots due to cotunneling. The system is treated using the Bloch-Redfield generalized master equation for the Schrieffer-Wolff transformed Hamiltonian. We show that the decoherence, characterized through a relaxation $\tau_{r}$ and a dephasing time $\tau_{\phi}$, can be controlled through the external voltage and that the optimum point, where these times are maximum, is not necessarily in equilibrium. We outline the mechanism of this nonequilibrium-induced enhancement of lifetime and coherence. We discuss the relevance of our results for recent charge qubit experiments.Comment: 5 pages, 5 figure

Patient experiences: a systematic review of quality improvement interventions in a hospital setting

Purpose: In the era of value-based healthcare, one strives for the most optimal outcomes and experiences from the perspective of the patient. So, patient experiences have become a key quality indicator for healthcare. While these are supposed to drive quality improvement (QI), their use and effectiveness for this purpose has been questioned. The aim of this systematic review was to provide insight into QI interventions used in a hospital setting and their effects on improving patient experiences, and possible barriers and promoters for QI work. Methods: Prisma guidelines were used to design this review. International academic literature was searched in Embase, Medline OvidSP, Web of Science, Cochrane Central, PubMed Publisher, Scopus, PsycInfo, and Google Scholar. In total, 3,289 studies were retrieved and independently screened by the first two authors for eligibility and methodological quality. Data was extracted on the study purpose, setting, design, targeted patient experience domains, QI strategies, results of QI, barriers, and promotors for QI. Results: Twenty-one pre–post intervention studies were included for review. The methodological quality of the included studies was assessed using a Critical Appraisal Skills Program (CASP) Tool. QI strategies used were staff education, patient education, audit and feedback, clinician reminders, organizational change, an

Determinants of a successful problem list to support the implementation of the problem-oriented medical record according to recent literature

Background: A problem-oriented approach is one of the possibilities to organize a medical record. The problem-oriented medical record (POMR) - a structured organization of patient information per presented medical problem- was introduced at the end of the sixties by Dr. Lawrence Weed to aid dealing with the multiplicity of patient problems. The problem list as a precondition is the centerpiece of the problem-oriented medical record (POMR) also called problem-oriented record (POR). Prior to the digital era, paper records presented a flat list of medical problems to the healthcare professional without the features that are possible with current technology. In modern EHRs a POMR based on a structured problem list can be used for clinical decision support, registries, order management, population health, and potentially other innovative functionality in the future, thereby providing a new incentive to the implementation and use of the POMR. Methods: On both 12 May 2014 and 1 June 2015 a systematic literature search was conducted. From the retrieved articles statements regarding the POMR and related to successful or non-successful implementation, were categorized. Generic determinants were extracted from these statements. Results: In this research 38 articles were included. The literature analysis led to 12 generic determinants: clinical practice/reasoning, complete and accurate problem list, data structure/content, efficiency, functionality, interoperability, multi-disciplinary, overview of patient information, quality of care

Effect of inelastic scattering on parametric pumping

Pumping of charge in phase-coherent mesoscopic systems due to the out-of-phase modulation of two parameters has recently found considerable interest. We investigate the effect of inelastic processes on the adiabatically pumped current through a two terminal mesoscopic sample. We find that the loss of coherence does not suppress the pumped charge but rather an additional physical mechanism for an incoherent pump effect comes into play. In a fully phase incoherent system the pump effect is similar to a rectification effect