Numerical Evidence for Robustness of Environment-Assisted Quantum Transport

Recent theoretical studies show that decoherence process can enhance transport efficiency in quantum systems. This effect is known as environment-assisted quantum transport (ENAQT). The role of ENAQT in optimal quantum transport is well investigated, however, it is less known how robust ENAQT is with respect to variations in the system or its environment characteristic. Toward answering this question, we simulated excitonic energy transfer in Fenna-Matthews-Olson (FMO) photosynthetic complex. We found that ENAQT is robust with respect to many relevant parameters of environmental interactions and Frenkel-exciton Hamiltonian including reorganization energy, bath frequency cutoff, temperature, and initial excitations, dissipation rate, trapping rate, disorders, and dipole moments orientations. Our study suggests that the ENAQT phenomenon can be exploited in robust design of highly efficient quantum transport systems.Comment: arXiv admin note: substantial text overlap with arXiv:1104.481

Preventing effect of vitamin E on oocytes apoptosis in morphinetreated mice

Several studies have shown that Morphine Sulfate affects on fertility, embryogenesis and consequent pregnancy loss and ultrastructural alterations of oocytes in animal model. This study was done to determine the effect of morphine sulfate on oocytes apoptosis and preventive role of daily supplementation of Vitamin E on oocytes apoptosis in morphine sulfate -treated mice. Twenty-four NMARI female mice were randomly allocated into four experimental groups. For 15 days, control group received saline (0.2 ml/day by subcutaneous injection), group I Vitamin E (60 mg/kg/day orally), group II Morphine Sulfate (10 mg/kg/day by subcutaneous injection) and group III Morphine Sulfate with Vitamin E (60 mg/kg/day orally). Then, animals were superovulated with PSMG (10 Units) and 10 Unites of HCG. The next day the animals were sacrificed, oocytes were flushed from each fallopian tube. The collected oocytes were subjected to determine apoptosis by Tunnel assay with using Fluorescent Microscope. According to our results, the number of retrieved oocytes were 121, 132, 86 and 114 in control, experimental group I, II and III, respectively. Morphine Sulfate treatment increased apoptosis in oocytes to 17.44% whereas oocytes apoptosis was 4.13% in Controls. Supplementation with Vitamin E in Morphine Sulfate -treated mice reduced the oocytes apoptosis to 7.01%. This study showed that Morphine can increase apoptosis in oocytes and Vitamin E treatment significantly reduces oocytes apoptosis in the Morphine Sulfate -treated mice

Robust Quantum Error Correction via Convex Optimization

We present a semidefinite program optimization approach to quantum error correction that yields codes and recovery procedures that are robust against significant variations in the noise channel. Our approach allows us to optimize the encoding, recovery, or both, and is amenable to approximations that significantly improve computational cost while retaining fidelity. We illustrate our theory numerically for optimized 5-qubit codes, using the standard [5,1,3] code as a benchmark. Our optimized encoding and recovery yields fidelities that are uniformly higher by 1-2 orders of magnitude against random unitary weight-2 errors compared to the [5,1,3] code with standard recovery. We observe similar improvement for a 4-qubit decoherence-free subspace code.Comment: 4 pages, including 3 figures. v2: new example

Locally Optimal Control of Quantum Systems with Strong Feedback

For quantum systems with high purity, we find all observables that, when continuously monitored, maximize the instantaneous reduction in the von Neumann entropy. This allows us to obtain all locally optimal feedback protocols with strong feedback, and explicit expressions for the best such protocols for systems of size N <= 4. We also show that for a qutrit the locally optimal protocol is the optimal protocol for a given range of control times, and derive an upper bound on all optimal protocols with strong feedback.Comment: 4 pages, Revtex4. v2: published version (some errors corrected

Flexibility Ranking of Water Distribution System Designs Under Future Mechanical and Hydraulic Uncertainty

AbstractAnnually a large amount of money should be spent by water authorities to adapt and update water distribution systems (WDSs)to the latest client's needs and variations known as adaptation cost. To prevent or lessen WDSs’ adaptation cost it is essential to insert a level of flexibility into WDS layouts from the very beginning in planning or designing stages [1]. This study proposed a simple technique based on multi-criteria decision analysis to rank a set of WDS layouts based on their level of flexibility under future mechanical and hydraulic uncertainty

Geometrical effects on energy transfer in disordered open quantum systems

We explore various design principles for efficient excitation energy transport in complex quantum systems. We investigate energy transfer efficiency in randomly disordered geometries consisting of up to 20 chromophores to explore spatial and spectral properties of small natural/artificial Light-Harvesting Complexes (LHC). We find significant statistical correlations among highly efficient random structures with respect to ground state properties, excitonic energy gaps, multichromophoric spatial connectivity, and path strengths. These correlations can even exist beyond the optimal regime of environment-assisted quantum transport. For random configurations embedded in spatial dimensions of 30 A and 50 A, we observe that the transport efficiency saturates to its maximum value if the systems contain 7 and 14 chromophores respectively. Remarkably, these optimum values coincide with the number of chlorophylls in (Fenna-Matthews-Olson) FMO protein complex and LHC II monomers, respectively, suggesting a potential natural optimization with respect to chromophoric density.Comment: 11 pages, 10 figures. Expanded from the former appendix to arXiv:1104.481