Determination of maximal Gaussian entanglement achievable by feedback-controlled dynamics

We determine a general upper bound for the steady-state entanglement achievable by continuous feedback for systems of any number of bosonic degrees of freedom. We apply such a bound to the specific case of parametric interactions - the most common practical way to generate entanglement in quantum optics - and single out optimal feedback strategies that achieve the maximal entanglement. We also consider the case of feedback schemes entirely restricted to local operations and compare their performance to the optimal, generally nonlocal, schemes.Comment: 4 pages. Published versio

Quantitative determination of pumpkin seed amino acids by gas-liquid chromatography

The objectives of this study were to determine whether pumpkin seed (Cucurbita pepo var. Lady Godiva) grown in Tennessee differs in amino acid composition from that grown in Minnesota and to develop a simple, quick and inexpensive routine laboratory technique for the quantitation of amino acids. Defatted pumpkin seed was hydrolyzed with 6N HC1 at 145° C for 4 h. Ion exchange was carried out for the clean-up of the amino acids. Prepurified amino acids were derivatized, first by esterification with isobutanol-3N HC1 at 120° C for 30 minutes and then acylation with heptafluorobutyric anhydride at 150° C for 10 minutes. Mixtures were quantitated by gas-liquid chromatography through a column packed with 3% SE 30 on 100-120 mesh Chromosorb W, HP using pipecolinic acid as the internal standard. Data gathered in this study indicated that the percentage of five amino acids, glutamic acid, aspartic acid, glycine, lysine and proline, was higher than literature values. The other amino acids were lower in concentration

Unconventional domain wall magnetoresistance of patterned Ni/Nb bilayer structures below superconducting transition temperature of Nb

Scattering of spin-up and spin-down electrons while passing through a ferromagnetic domain wall leads to an additional resistance for transport current, usually observed prominently in constricted magnetic structures. In this report, we use the resistance of the domain wall as a probe to find indirect signatures of the theoretically predicted spin-singlet supercurrent to spin-triplet supercurrent conversion effect of ferromagnetic domain walls. Here we examine the domain wall induced resistance in Ni stripe in a bilayer Ni/Nb geometry in the normal state and in the superconducting state of Nb. By making a 6um wide gap in the top Nb layer we routed the transport current through the Ni layer in the normal state and in the superconducting state of Nb. In the normal state of Nb, in-field transport measurements showed a clear domain wall magneto-resistance (DWMR) peak near the coercive field, where the domain wall density is expected to be maximum. Interestingly, however, below the superconducting transition temperature of Nb, the DWMR peak of the Ni layer showed a sharp drop in the field range where the number of domain walls becomes maximum. This observation may be a possible signature of magnetic domain wall induced spin-triplet correlations in the Ni layer due to the direct injection of spin-singlet Cooper pairs from Nb into the magnetic domain walls

Effect of herbal formulation AV/DAC-16 supplementation on rumen profiles in buffalo calves (Bubalus bubalis)

ABSTRACT[R1] 12 healthy buffalo calves with BW range 100-150 kg were fistulated and divided into two goups of 6 animals each. Control group animals were fed on conventional diet comprising of wheat straw (2 kg), green fodder (8 kg), concentrate (1.0 kg) and mineral mixture (0.050kg). The animals of the treatment group were kept on diet similar to the control group along with feeding of herbally formulated [R2] drug AV/DAC-16@ 15 gms/day for 21 days. Each animal was sampled for three consecutive days at 0 hr i.e., immediately before feeding and subsequent samples were taken at 2, 4 and 6 hr intervals after feeding. There was a significant fall in pH at 2 and 4 hours post-prandial and in Methylene BlueReductionTime[R3] during the entire observation period. TVFA concentration increased significantly in the treatment group. Though oral administration [R4] of AV/DAC-16 did not have any prominent effect on the protozoal count, the bacterial count increased significantly in comparison to control group. Total nitrogen concentrations fell significantly while a significant increase was observed in the ammonia nitrogen content in the supplemented group at 6 hours after feeding. The animals of supplemented group showed a significant increase in body weights.Key words: Digestibility, Wheat Straw[R1]?? Reply: Figure deleted.[R2]How was offered to the animals?Reply: The drug was given by opening the mouth of the animal using standard animal husbandry procedure.[R3]describe the acronyms in the abstractReply: MBRT- Methylene  Blue Reduction Time[R4]Direct?? Describe aboveReply: Per oral administration i.e., through mouth

An All-But-One Entropic Uncertainty Relation, and Application to Password-based Identification

Entropic uncertainty relations are quantitative characterizations of Heisenberg's uncertainty principle, which make use of an entropy measure to quantify uncertainty. In quantum cryptography, they are often used as convenient tools in security proofs. We propose a new entropic uncertainty relation. It is the first such uncertainty relation that lower bounds the uncertainty in the measurement outcome for all but one choice for the measurement from an arbitrarily large (but specifically chosen) set of possible measurements, and, at the same time, uses the min-entropy as entropy measure, rather than the Shannon entropy. This makes it especially suited for quantum cryptography. As application, we propose a new quantum identification scheme in the bounded quantum storage model. It makes use of our new uncertainty relation at the core of its security proof. In contrast to the original quantum identification scheme proposed by Damg{\aa}rd et al., our new scheme also offers some security in case the bounded quantum storage assumption fails hold. Specifically, our scheme remains secure against an adversary that has unbounded storage capabilities but is restricted to non-adaptive single-qubit operations. The scheme by Damg{\aa}rd et al., on the other hand, completely breaks down under such an attack.Comment: 33 pages, v

Discrimination between pure states and mixed states

In this paper, we discuss the problem of determining whether a quantum system is in a pure state, or in a mixed state. We apply two strategies to settle this problem: the unambiguous discrimination and the maximum confidence discrimination. We also proved that the optimal versions of both strategies are equivalent. The efficiency of the discrimination is also analyzed. This scheme also provides a method to estimate purity of quantum states, and Schmidt numbers of composed systems

Entropic uncertainty relations and entanglement

We discuss the relationship between entropic uncertainty relations and entanglement. We present two methods for deriving separability criteria in terms of entropic uncertainty relations. Especially we show how any entropic uncertainty relation on one part of the system results in a separability condition on the composite system. We investigate the resulting criteria using the Tsallis entropy for two and three qubits.Comment: 8 pages, 3 figures, v2: small change

Extremal extensions of entanglement witnesses: Unearthing new bound entangled states

In this paper, we discuss extremal extensions of entanglement witnesses based on Choi's map. The constructions are based on a generalization of the Choi map due to Osaka, from which we construct entanglement witnesses. These extremal extensions are powerful in terms of their capacity to detect entanglement of positive under partial transpose (PPT) entangled states and lead to unearthing of entanglement of new PPT states. We also use the Cholesky-like decomposition to construct entangled states which are revealed by these extremal entanglement witnesses.Comment: 8 pages 6 figures revtex4-

A Stronger Subadditivity of Entropy

The strong subadditivity of entropy plays a key role in several areas of physics and mathematics. It states that the entropy S[\rho]= - Tr (\rho \ln \rho) of a density matrix \rho_{123} on the product of three Hilbert spaces satisfies S[\rho_{123}] - S[\rho_{23}] \leq S[\rho_{12}]- S[\rho_2]. We strengthen this to S[\rho_{123}] - S[\rho_{12}] \leq \sum_\alpha n^\alpha (S[\rho_{23}^\alpha ] - S[\rho_2^\alpha ]), where the n^\alpha are weights and the \rho_{23}^\alpha are partitions of \rho_{23}. Correspondingly, there is a strengthening of the theorem that the map A -> Tr \exp[L + \ln A] is concave. As applications we prove some monotonicity and convexity properties of the Wehrl entropy and entropy inequalities for quantum gases.Comment: LaTeX2e, 24 page