Robust Multi-Partite Multi-Level Quantum Protocols

We present a tripartite three-level state that allows a secret sharing protocol among the three parties, or a quantum key distribution protocol between any two parties. The state used in this scheme contains entanglement even after one system is traced out. We show how to utilize this residual entanglement for quantum key distribution purposes, and propose a realization of the scheme using entanglement of orbital angular momentum states of photons.Comment: 9 pages, 2 figure

Synchronous thymoma and oligodendroglioma: A rare association

Introduction Patients with thymoma are found to have another systemic illness and a broadly increased risk for secondary malignancies. We present the case of a 53-year-old female patient who harbored two synchronous primary malignant neoplasms - an anaplastic oligodendroglioma of the right frontal lobe and an anterior mediastinal thymoma. Presentation of case A 53-year-old female patient presented in her first hospital admission with nausea, chest pain and non-pulsatile bitemporal headache. Continued headache and nausea along with negative cardiac findings prompted radiological evaluation including chest CT scan and brain CT scan which revealed simultaneous anterior mediastinal mass and frontal lobe calcification respectively. The patient underwent craniotomy and the pathological diagnosis was anaplastic oligodendriglioma. The anterior mediastinal tumor resection was performed three months later, while the patient had no newly onset of any symptoms necessitating more investigation. Discussion Multiple primary malignancies have been diagnosed by the following criteria: each tumor must have an obvious picture of malignancy, each must be separate and discrete and the probability that one was a metastatic lesion from the other must be excluded. Treatment strategies in cases of double malignancy involve treating the malignancy that is more advanced first. In our case we concluded that synchronous double malignancy can be treated successfully according to the above mentioned criteria. Conclusion Clinicians should be aware of the possibility of synchronous malignancies in order to use screening procedures in patients with reported increased risk of double malignancy. Such clinical alertness may lead to a better outcome for double primary tumor cases. © 2016 The Authors. Published by Elsevier Ltd

Optical vernier technique for in-situ measurement of the length of long Fabry-Perot cavities

We propose a method for in-situ measurement of the length of kilometer size Fabry-Perot cavities in laser gravitational wave detectors. The method is based on the vernier, which occurs naturally when the laser incident on the cavity has a sideband. By changing the length of the cavity over several wavelengths we obtain a set of carrier resonances alternating with sideband resonances. From the measurement of the separation between the carrier and a sideband resonance we determine the length of the cavity. We apply the technique to the measurement of the length of a Fabry-Perot cavity in the Caltech 40m Interferometer and discuss the accuracy of the technique.Comment: LaTeX 2e, 12 pages, 4 figure

Vibration-enhanced quantum transport

In this paper, we study the role of collective vibrational motion in the phenomenon of electronic energy transfer (EET) along a chain of coupled electronic dipoles with varying excitation frequencies. Previous experimental work on EET in conjugated polymer samples has suggested that the common structural framework of the macromolecule introduces correlations in the energy gap fluctuations which cause coherent EET. Inspired by these results, we present a simple model in which a driven nanomechanical resonator mode modulates the excitation energy of coupled quantum dots and find that this can indeed lead to an enhancement in the transport of excitations across the quantum network. Disorder of the on-site energies is a key requirement for this to occur. We also show that in this solid state system phase information is partially retained in the transfer process, as experimentally demonstrated in conjugated polymer samples. Consequently, this mechanism of vibration enhanced quantum transport might find applications in quantum information transfer of qubit states or entanglement.Comment: 7 pages, 6 figures, new material, included references, final published versio

Quantized Rotation of Atoms From Photons with Orbital Angular Momentum

We demonstrate the coherent transfer of the orbital angular momentum of a photon to an atom in quantized units of hbar, using a 2-photon stimulated Raman process with Laguerre-Gaussian beams to generate an atomic vortex state in a Bose-Einstein condensate of sodium atoms. We show that the process is coherent by creating superpositions of different vortex states, where the relative phase between the states is determined by the relative phases of the optical fields. Furthermore, we create vortices of charge 2 by transferring to each atom the orbital angular momentum of two photons.Comment: New version, 4 pages and 3 figures, accepted for publication in Physical Review Letter