| 1. |
- Diehl, S., et al.
(författare)
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Quantum states and phases in driven open quantum systems with cold atoms
- 2008
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Ingår i: Nature Physics. - : Nature Publishing Group. - 1745-2473 .- 1745-2481. ; 4:11, s. 878-883
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Tidskriftsartikel (refereegranskat)abstract
- An open quantum system, the time evolution of which is governed by a master equation, can be driven into a given pure quantum state by an appropriate design of the coupling between the system and the reservoir. This provides a route towards preparing many-body states and non-equilibrium quantum phases by quantum-reservoir engineering. Here, we discuss the example of a driven dissipative Bose–Einstein condensate of bosons and of paired fermions, where atoms in an optical lattice are coupled to a bath of Bogoliubov excitations and the atomic current represents local dissipation. In the absence of interactions, the lattice gas is driven into a pure state with long-range order. Weak interactions lead to a weakly mixed state, which in three dimensions can be understood as a depletion of the condensate, and in one and two dimensions exhibits properties reminiscent of a Luttinger liquid or a Kosterlitz–Thouless critical phase at finite temperature, with the role of the ’finite temperature’ taken by the interactions.
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| 2. |
- Kraus, B., et al.
(författare)
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Preparation of entangled states by quantum Markov processes
- 2008
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - : American Physical Society. - 1050-2947 .- 1094-1622. ; 78:4
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the possibility of using a dissipative process to prepare a quantum system in a desired state. We derive for any multipartite pure state a dissipative process for which this state is the unique stationary state and solve the corresponding master equation analytically. For certain states, such as the cluster states, we use this process to show that the jump operators can be chosen quasilocally, i.e. they act nontrivially only on a few, neighboring qubits. Furthermore, the relaxation time of this dissipative process is independent of the number of subsystems. We demonstrate the general formalism by considering arbitrary matrix-product states or projected entangled pair states. In particular, we show that the ground state of the Affleck-Kennedy-Lieb-Tasaki model can be prepared employing a quasi-local dissipative process.
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| 3. |
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| 4. |
- Shur, Vladimir, et al.
(författare)
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Nanoscale Domain Effects in Ferroelectrics. Formation and Evolution of Self-Assembled Structures in LiNbO3and LiTaO3
- 2007
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Ingår i: Ferroelectrics (Print). - : Informa UK Limited. - 0015-0193 .- 1563-5112. ; 354, s. 145-157
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Tidskriftsartikel (refereegranskat)abstract
- We discuss the most interesting nanoscale domain effects resulting in formation andevolution of self-assembled domain structures in various representatives of LiNbO3 andLiTaO3 family. Several exotic domain kinetic scenarios for complete suppression of theclassical wall motion have been revealed. It has been shown that the modification of thesurface layer allows to obtain: (1) the wall motion controlled by merging with nanoscaledomains generated in front of the moving wall and (2) the discrete switching by enlarge-ment of the web-like self-assembled ensemble of isolated domains. The formation ofnanoscale quasi-periodic and self-similar structures during cooling after pulse heatingwithout any application of external electric field was studied. It has been shown thatall experimental results can be explained, if the retardation of the bulk screening of thedepolarization field is taken into account.
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| 5. |
- Renstrom, P, et al.
(författare)
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Non-contact ACL injuries in female athletes: an International Olympic Committee current concepts statement
- 2008
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Ingår i: British journal of sports medicine. - : BMJ. - 1473-0480 .- 0306-3674. ; 42:6, s. 394-412
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Forskningsöversikt (refereegranskat)abstract
- The incidence of anterior cruciate ligament (ACL) injury remains high in young athletes. Because female athletes have a much higher incidence of ACL injuries in sports such as basketball and team handball than male athletes, the IOC Medical Commission invited a multidisciplinary group of ACL expert clinicians and scientists to (1) review current evidence including data from the new Scandinavian ACL registries; (2) critically evaluate high-quality studies of injury mechanics; (3) consider the key elements of successful prevention programmes; (4) summarise clinical management including surgery and conservative management; and (5) identify areas for further research. Risk factors for female athletes suffering ACL injury include: (1) being in the preovulatory phase of the menstrual cycle compared with the postovulatory phase; (2) having decreased intercondylar notch width on plain radiography; and (3) developing increased knee abduction moment (a valgus intersegmental torque) during impact on landing. Well-designed injury prevention programmes reduce the risk of ACL for athletes, particularly women. These programmes attempt to alter dynamic loading of the tibiofemoral joint through neuromuscular and proprioceptive training. They emphasise proper landing and cutting techniques. This includes landing softly on the forefoot and rolling back to the rearfoot, engaging knee and hip flexion and, where possible, landing on two feet. Players are trained to avoid excessive dynamic valgus of the knee and to focus on the "knee over toe position'' when cutting.
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| 6. |
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| 7. |
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| 8. |
- Shur, Vladimir, et al.
(författare)
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Modification of the Domain Kinetics in Congruent Lithium Niobate by Proton Exchanged Surface Layers
- 2006
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Konferensbidrag (refereegranskat)abstract
- We have studied the domain kinetics in congruent lithium niobate (CLN) single crystals with different types of the proton exchanged surface layers. The influence of the artificial dielectric layers and the surface gradient of the spontaneous polarization on the domain structure geometry, the shape of the individual domains, and the switching parameters were demonstrated. It was shown that after several cycles of polarization reversal the domain kinetics changes drastically. As a result the domain geometry is defined by spatial distribution of the residual domains existing in the area of domain merging during the previous switching. The role of residual domains increases with the cycle number.
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| 9. |
- Zeleniuch-Jacquotte, Anne, et al.
(författare)
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Circulating enterolactone and risk of endometrial cancer
- 2006
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Ingår i: International Journal of Cancer. - : Wiley. - 0020-7136 .- 1097-0215. ; 119:10, s. 2376-2381
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Tidskriftsartikel (refereegranskat)abstract
- It has been suggested that phytoestrogens protect against hormone-dependent cancers. Lignans are the main class of phytoestrogens in Western diets. We conducted a prospective study of endometrial cancer and circulating levels of the main human lignan, enterolactone. The design was a case-control study nested within 3 prospective cohort studies, in New York, Sweden and Italy. Serum or plasma samples had been collected at enrollment and stored at -80 degrees C. A total of 153 cases, diagnosed a median of 5.3 years after blood donation, and 271 matched controls were included. No difference in circulating enterolactone was observed between cases (median, 19.2 nmol/L) and controls (18.5 nmol/L). Adjusting for body mass index, the odds ratio for the top tertile of enterolactone, as compared to the lowest was 1.2 (95% CI, 0.7-2.0; p for trend = 0.53). Lack of association was observed in both pre- and postmenopausal women. No correlation was observed between enterolactone and circulating estrogens or SHBG in healthy postmenopausal women. These results do not support a protective role of circulating lignans, in the range of levels observed, against endometrial cancer.
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