Oscillatory Tunnel Splittings in Spin Systems: A Discrete Wentzel-Kramers-Brillouin Approach

Certain spin Hamiltonians that give rise to tunnel splittings that are viewed in terms of interfering instanton trajectories, are restudied using a discrete WKB method, that is more elementary, and also yields wavefunctions and preexponential factors for the splittings. A novel turning point inside the classically forbidden region is analysed, and a general formula is obtained for the splittings. The result is appled to the \Fe8 system. A previous result for the oscillation of the ground state splitting with external magnetic field is extended to higher levels.Comment: RevTex, one ps figur

Isolating CP-violating \gamma ZZ coupling in e+e- \to \gamma Z with transverse beam polarizations

We revisit the process $e^+e^- \to \gamma Z$ at the ILC with transverse beam polarization in the presence of anomalous CP-violating $\gamma Z Z$ coupling $\lambda_1$ and $\gamma \gamma Z$ coupling $\lambda_2$. We point out that if the final-state spins are resolved, then it becomes possible to fingerprint the anomalous coupling {\rm Re}$\lambda_1$.90% confidence level limit on {\rm Re}$\lambda_1$ achievable at ILC with center-of-mass energy of 500 GeV or 800 GeV with realistic initial beam polarization and integrated luminosity is of the order of few times of $10^{-2}$ when the helicity of $Z$ is used and $10^{-3}$ when the helicity of $\gamma$ is used. The resulting corrections at quadratic order to the cross section and its influence on these limits are also evaluated and are shown to be small. The benefits of such polarization programmes at the ILC are compared and contrasted for the process at hand. We also discuss possible methods by which one can isolate events with a definite helicity for one of the final-state particles.Comment: 13 pages, 9 figures, using RevTex; v2 is a significantly revised version of v1, and corresponds to the version that has been published in Physical Review

Innovative Double H Metamaterial Structure for Amelioration in Patch Antenna Parameters

A rectangular microstrip patch antenna along with a SSRR based “Double H” shaped metamaterial is proposed and analyzed at a height of 3.2mm from the ground plane. This work is mainly focused on increasing the potential parameters of microstrip patch antennas. The patch antenna along with the proposed metamaterial structure is designed to resonate at 1.84GHz. The impedance bandwidth of the patch antenna along with the proposed metamaterial structure is improved by 12.9MHz and return loss is reduced by 9.89dB. All the simulation work is done by using CST-MWS Software. Double-Negative properties (Negative Permeability and Permittivity) of the proposed metamaterial structure have also been verified using Nicolson-Ross-Weir method (NRW)

Quantum Lightning Never Strikes the Same State Twice

Public key quantum money can be seen as a version of the quantum no-cloning theorem that holds even when the quantum states can be verified by the adversary. In this work, investigate quantum lightning, a formalization of "collision-free quantum money" defined by Lutomirski et al. [ICS'10], where no-cloning holds even when the adversary herself generates the quantum state to be cloned. We then study quantum money and quantum lightning, showing the following results: - We demonstrate the usefulness of quantum lightning by showing several potential applications, such as generating random strings with a proof of entropy, to completely decentralized cryptocurrency without a block-chain, where transactions is instant and local. - We give win-win results for quantum money/lightning, showing that either signatures/hash functions/commitment schemes meet very strong recently proposed notions of security, or they yield quantum money or lightning. - We construct quantum lightning under the assumed multi-collision resistance of random degree-2 systems of polynomials. - We show that instantiating the quantum money scheme of Aaronson and Christiano [STOC'12] with indistinguishability obfuscation that is secure against quantum computers yields a secure quantum money schem

Private Outsourcing of Polynomial Evaluation and Matrix Multiplication using Multilinear Maps

{\em Verifiable computation} (VC) allows a computationally weak client to outsource the evaluation of a function on many inputs to a powerful but untrusted server. The client invests a large amount of off-line computation and gives an encoding of its function to the server. The server returns both an evaluation of the function on the client's input and a proof such that the client can verify the evaluation using substantially less effort than doing the evaluation on its own. We consider how to privately outsource computations using {\em privacy preserving} VC schemes whose executions reveal no information on the client's input or function to the server. We construct VC schemes with {\em input privacy} for univariate polynomial evaluation and matrix multiplication and then extend them such that the {\em function privacy} is also achieved. Our tool is the recently developed {mutilinear maps}. The proposed VC schemes can be used in outsourcing {private information retrieval (PIR)}.Comment: 23 pages, A preliminary version appears in the 12th International Conference on Cryptology and Network Security (CANS 2013

Giant lipoma: an unusual cause of carpal tunnel syndrome

Carpal tunnel syndrome, in its idiopathic form, is an extremely common entrapment neuropathy in the clinical practice however secondary compressive causes are rare. Among secondary causes, tumors are even rarer. Although lipomas are the most common soft tissue tumor in the body, <5% of the benign tumors of the hand are lipomas. A 48-year old manual laborer man presented to us with a two-year history of numbness, tingling and burning pain in the palmar surface of the left hand and fingers along with a progressively increasing swelling in the hand and wrist. His medical history was unremarkable and no trauma episode was reported. According to the clinical examination and the result of median nerve conduction study (NCS) the diagnosis of carpal tunnel syndrome was established. Operative release of the transverse carpal ligament was subsequently performed along with excision of the lipoma using extensile open approach. Intraoperatively, median nerve and its digital branches were found to be stretched over the giant lipoma causing substantial compression to median nerve. Histopathological findings of the resected mass were consistent with lipoma. After two years the patient was pain-free without any sign of tumor recurrence. Lipomas are infrequently seen in hand and wrist, however giant lipoma as a cause of secondary carpal tunnel syndrome is even more rare, which makes this case interesting.Key words: Lipoma, carpal tunnel syndrome, median nerve, nerve compressio