264 research outputs found
Proposed direct test of a certain type of noncontextuality in quantum mechanics
The noncontextuality of quantum mechanics can be directly tested by measuring
two entangled particles with more than two outcomes per particle. The two
associated contexts are "interlinked" by common observables.Comment: 9 pages 2 figure
Experimentally testable state-independent quantum contextuality
We show that there are Bell-type inequalities for noncontextual theories that
are violated by any quantum state. One of these inequalities between the
correlations of compatible measurements is particularly suitable for testing
this state-independent violation in an experiment.Comment: REVTeX4, 4 pages, 1 figur
Kochen-Specker theorem for a single qubit using positive operator-valued measures
A proof of the Kochen-Specker theorem for a single two-level system is
presented. It employs five eight-element positive operator-valued measures and
a simple algebraic reasoning based on the geometry of the dodecahedron.Comment: REVTeX4, 4 pages, 2 figure
Higher BMC and areal BMD in Children and Grandchildren of Individuals with Hip or Knee Replacement
The relationship between aBMD and osteoarthritis (OA) remains unclear. We compared aBMD, BMC and bone size among children and grandchildren of Hutterites with hip or knee replacement (n=23 each) to children and grandchildren of age- and sex-matched controls (178 children and 267 grandchildren). There were no differences in anthropometric measures or activity levels between case and control probands, but femoral neck (FN) and spine (LS) aBMD and Z-scores were greater in cases than controls (0.89 vs. 0.80 g/cm2; 1.15 vs. 1.03 g/cm2; 1.5 vs. 0.8; 2.4 vs. 1.2: all por =2 years post-menarcheal or males\u3e or =18 years): 33 were not classified. Post-menarcheal, but not premenarcheal, granddaughters of cases had greater hip, FN and LS aBMD Z-scores (0.7 vs. -0.1; 0.6 vs. -0.1; 0.8 vs. -0.3); greater hip and spine aBMD (1.03 vs. 0.95, 1.10 vs. 0.98 g/cm2); greater femoral neck and spine BMC (4.77 vs. 4.21, 66.7 vs. 55.4 g); and greater spine bone area (60.7 vs. 56.6 cm2) compared to granddaughters of controls (all,
A feasible "Kochen-Specker" experiment with single particles
We present a simple experimental scheme which can be used to demonstrate an
all-or-nothing type contradiction between non-contextual hidden variables and
quantum mechanics. The scheme, which is inspired by recent ideas by Cabello and
Garcia-Alcaine, shows that even for a single particle, path and spin
information cannot be predetermined in a non-contextual way.Comment: 4 pages, 3 figure
The diagonalization method in quantum recursion theory
As quantum parallelism allows the effective co-representation of classical
mutually exclusive states, the diagonalization method of classical recursion
theory has to be modified. Quantum diagonalization involves unitary operators
whose eigenvalues are different from one.Comment: 15 pages, completely rewritte
Causality - Complexity - Consistency: Can Space-Time Be Based on Logic and Computation?
The difficulty of explaining non-local correlations in a fixed causal
structure sheds new light on the old debate on whether space and time are to be
seen as fundamental. Refraining from assuming space-time as given a priori has
a number of consequences. First, the usual definitions of randomness depend on
a causal structure and turn meaningless. So motivated, we propose an intrinsic,
physically motivated measure for the randomness of a string of bits: its length
minus its normalized work value, a quantity we closely relate to its Kolmogorov
complexity (the length of the shortest program making a universal Turing
machine output this string). We test this alternative concept of randomness for
the example of non-local correlations, and we end up with a reasoning that
leads to similar conclusions as in, but is conceptually more direct than, the
probabilistic view since only the outcomes of measurements that can actually
all be carried out together are put into relation to each other. In the same
context-free spirit, we connect the logical reversibility of an evolution to
the second law of thermodynamics and the arrow of time. Refining this, we end
up with a speculation on the emergence of a space-time structure on bit strings
in terms of data-compressibility relations. Finally, we show that logical
consistency, by which we replace the abandoned causality, it strictly weaker a
constraint than the latter in the multi-party case.Comment: 17 pages, 16 figures, small correction
NMR quality control of fragment libraries for screening
Fragment-based screening has evolved as a remarkable approach within the drug discovery process both in the industry and academia. Fragment screening has become a more structure-based approach to inhibitor development, but also towards development of pathway-specific clinical probes. However, it is often witnessed that the availability, immediate and long-term, of a high quality fragment-screening library is still beyond the reach of most academic laboratories. Within iNEXT (Infrastructure for NMR, EM and X-rays for Translational research), a EU-funded Horizon 2020 program, a collection of 782 fragments were assembled utilizing the concept of "poised fragments" with the aim to facilitate downstream synthesis of ligands with high affinity by fragment ligation. Herein, we describe the analytical procedure to assess the quality of this purchased and assembled fragment library by NMR spectroscopy. This quality assessment requires buffer solubility screening, comparison with LC/MS quality control and is supported by state-of-the-art software for high throughput data acquisition and on-the-fly data analysis. Results from the analysis of the library are presented as a prototype of fragment progression through the quality control process
Finite precision measurement nullifies the Kochen-Specker theorem
Only finite precision measurements are experimentally reasonable, and they
cannot distinguish a dense subset from its closure. We show that the rational
vectors, which are dense in S^2, can be colored so that the contradiction with
hidden variable theories provided by Kochen-Specker constructions does not
obtain. Thus, in contrast to violation of the Bell inequalities, no
quantum-over-classical advantage for information processing can be derived from
the Kochen-Specker theorem alone.Comment: 7 pages, plain TeX; minor corrections, interpretation clarified,
references update
- …