Quantum correlations from local amplitudes and the resolution of the Einstein-Podolsky-Rosen nonlocality puzzle

The Einstein-Podolsky-Rosen nonlocality puzzle has been recognized as one of the most important unresolved issues in the foundational aspects of quantum mechanics. We show that the problem is resolved if the quantum correlations are calculated directly from local quantities which preserve the phase information in the quantum system. We assume strict locality for the probability amplitudes instead of local realism for the outcomes, and calculate an amplitude correlation function.Then the experimentally observed correlation of outcomes is calculated from the square of the amplitude correlation function. Locality of amplitudes implies that the measurement on one particle does not collapse the companion particle to a definite state. Apart from resolving the EPR puzzle, this approach shows that the physical interpretation of apparently `nonlocal' effects like quantum teleportation and entanglement swapping are different from what is usually assumed. Bell type measurements do not change distant states. Yet the correlations are correctly reproduced, when measured, if complex probability amplitudes are treated as the basic local quantities. As examples we discuss the quantum correlations of two-particle maximally entangled states and the three-particle GHZ entangled state.Comment: Std. Latex, 11 pages, 1 table. Prepared for presentation at the International Conference on Quantum Optics, ICQO'2000, Minsk, Belaru

Calabi-Yau Orbifolds and Torus Coverings

The theory of coverings of the two-dimensional torus is a standard part of algebraic topology and has applications in several topics in string theory, for example, in topological strings. This paper initiates applications of this theory to the counting of orbifolds of toric Calabi-Yau singularities, with particular attention to Abelian orbifolds of C^D. By doing so, the work introduces a novel analytical method for counting Abelian orbifolds, verifying previous algorithm results. One identifies a p-fold cover of the torus T^{D-1} with an Abelian orbifold of the form C^D/Z_p, for any dimension D and a prime number p. The counting problem leads to polynomial equations modulo p for a given Abelian subgroup of S_D, the group of discrete symmetries of the toric diagram for C^D. The roots of the polynomial equations correspond to orbifolds of the form C^D/Z_p, which are invariant under the corresponding subgroup of S_Ds. In turn, invariance under this subgroup implies a discrete symmetry for the corresponding quiver gauge theory, as is clearly seen by its brane tiling formulation.Comment: 33 pages, 5 figures, 7 tables; version published on JHE

Are Interaction-free Measurements Interaction Free?

In 1993 Elitzur and Vaidman introduced the concept of interaction-free measurements which allowed finding objects without ``touching'' them. In the proposed method, since the objects were not touched even by photons, thus, the interaction-free measurements can be called as ``seeing in the dark''. Since then several experiments have been successfully performed and various modifications were suggested. Recently, however, the validity of the term ``interaction-free'' has been questioned. The criticism of the name is briefly reviewed and the meaning of the interaction-free measurements is clarified.Comment: 11 pages, 3 eps figures. Contribution to the ICQO 2000, Raubichi, Belaru

All-Versus-Nothing Proof of Einstein-Podolsky-Rosen Steering

Einstein-Podolsky-Rosen steering is a form of quantum nonlocality intermediate between entanglement and Bell nonlocality. Although Schr\"odinger already mooted the idea in 1935, steering still defies a complete understanding. In analogy to "all-versus-nothing" proofs of Bell nonlocality, here we present a proof of steering without inequalities rendering the detection of correlations leading to a violation of steering inequalities unnecessary. We show that, given any two-qubit entangled state, the existence of certain projective measurement by Alice so that Bob's normalized conditional states can be regarded as two different pure states provides a criterion for Alice-to-Bob steerability. A steering inequality equivalent to the all-versus-nothing proof is also obtained. Our result clearly demonstrates that there exist many quantum states which do not violate any previously known steering inequality but are indeed steerable. Our method offers advantages over the existing methods for experimentally testing steerability, and sheds new light on the asymmetric steering problem.Comment: 7 pages, 2 figures. Accepted in Sci. Re

Applications of real number theorem proving in PVS

This work is supported by funding from the EPSRC under grants EP/H500162, EP/F02309X and GR/S31242Real number theorem proving has many uses, particularly for verification of safety critical systems and systems for which design errors may be costly. We discuss a chain of developments building on real number theorem proving in PVS. This leads from the verification of aspects of an air traffic control system, through work on the integration of computer algebra and automated theorem proving to a new tool, NRV, first presented here that builds on the capabilities of Maple and PVS to provide a verified and automatic analysis of Nichols plots. This automates a standard technique used by control engineers and greatly improves assurance compared with the traditional method of visual inspection of the Nichols plots.Publisher PDFPeer reviewe

Clarifying Assumptions about Intraoperative Stress during Surgical Performance: More Than a Stab in the Dark: Reply

Ó The Author(s) 2011. This article is published with open access at Springerlink.com We thank Dr. Ali for his concise annotation of our efforts to validate a tool that evaluates mental workload in surgery [1, 2]. Unlike other safety critical domains, the field of surgery has been slow to acknowledge the impact of intraoperative stress on surgical performance, but recently a sea change has been triggered by authorities in the field of surgical education [3]. We agree with Ali that stress is not by default detrimental to performance. Our aim was to develop a diagnostic tool that identifies the factors that contribute to disrupted performance, should it occur. Indeed, studies of the effects of acute stress on operating performance have shown considerable variability, ranging from no effect to either facilitative or debilitative effects [3–5]. The Yerkes-Dodson law emerged from the earliest attempts to explain the relationship between physiological arousal and performance, but it has been criticized for treating stress as a unitary construct, influenced solely by physiological factors [6]. More recently, Catastrophe Theory has been invoked to model the relationship, using both physiological and psychological (cognitive anxiety) components of stress [7]. The model proposes that physiological arousal displays a mild inverted-U relationship with performance when cognitive anxiety is low, but that catastrophic declines in performance can occur if both physiological arousal and cognitive anxiety are high. Recent surgical literature has elucidated the complexity of M. Wilson (&

Distinct Genetic Lineages of Bactrocera caudata (Insecta: Tephritidae) Revealed by COI and 16S DNA Sequences

The fruit fly Bactrocera caudata is a pest species of economic importance in Asia. Its larvae feed on the flowers of Cucurbitaceae such as Cucurbita moschata. To-date it is distinguished from related species based on morphological characters. Specimens of B. caudata from Peninsular Malaysia and Indonesia (Bali and Lombok) were analysed using the partial DNA sequences of cytochrome c oxidase subunit I (COI) and 16S rRNA genes. Both gene sequences revealed that B. caudata from Peninsular Malaysia was distinctly different from B. caudata of Bali and Lombok, without common haplotype between them. Phylogenetic analysis revealed two distinct clades, indicating distinct genetic lineage. The uncorrected ‘p’ distance for COI sequences between B. caudata of Malaysia-Thailand-China and B. caudata of Bali-Lombok was 5.65%, for 16S sequences from 2.76 to 2.99%, and for combined COI and 16S sequences 4.45 to 4.46%. The ‘p’ values are distinctly different from intraspecific ‘p’ distance (0–0.23%). Both the B. caudata lineages are distinctly separated from related species in the subgenus Zeugodacus – B. ascita, B. scutellata, B. ishigakiensis, B. diaphora, B. tau, B. cucurbitae, and B. depressa. Molecular phylogenetic analysis indicates that the B. caudata lineages are closely related to B. ascita sp. B, and form a clade with B. scutellata, B. ishigakiensis, B. diaphora and B. ascita sp. A. This study provides additional baseline for the phylogenetic relationships of Bactrocera fruit flies of the subgenus Zeugodacus. Both the COI and 16S genes could be useful markers for the molecular differentiation and phylogenetic analysis of tephritid fruit flies

Premenopausal cardiovascular disease and age at natural menopause: a pooled analysis of over 170,000 women

Early menopause is associated with an increased risk of subsequent cardiovascular disease (CVD). Few studies have investigated the converse. We examined whether premenopausal CVD events are associated with early age at menopause. We pooled the individual data of 177,131 women from nine studies. We used multinomial logistic regression models to estimate multivariable relative risk ratios (RRR) and 95% confidence intervals (CI) for the associations between age at onset of premenopausal CVD events-including coronary heart disease (CHD) and stroke-and age at natural menopause. Altogether 1561 (0.9%) premenopausal participants reported CVD events (including 1130 CHD and 469 stroke) at a mean age of 41.3 years. Compared with women without any premenopausal CVD events, women who experienced a first CVD event before age 35 years had a twofold risk of menopause before age 45 years (early menopause); adjusted RRR (95% CI) of 1.92 (1.17, 3.14) for any CVD, 1.86 (1.01, 3.43) for CHD and 2.17 (1.43, 3.30) for stroke. Women who experienced a first premenopausal CVD event after age 40 years underwent a natural menopause at the expected age (around 51 years). These associations were robust to adjustment for smoking status, BMI, educational level, race/ethnicity, age at menarche, parity, hypertension and family history of CVD. For premenopausal women, a first CVD event before age 35 years is associated with a doubling of the risk of an early menopause, while a first CVD event occurred after 35 years indicates a normal menopause at around 51 years. Shared genetic and environmental factors (such as smoking), as well as compromised vasculature following CVD events, may contribute to this outcome