Quantum Network of Atom Clocks: A Possible Implementation with Neutral Atoms.

We propose a protocol for creating a fully entangled Greenberger-Horne-Zeilinger-type state of neutral atoms in spatially separated optical atomic clocks. In our scheme, local operations make use of the strong dipole-dipole interaction between Rydberg excitations, which give rise to fast and reliable quantum operations involving all atoms in the ensemble. The necessary entanglement between distant ensembles is mediated by single-photon quantum channels and collectively enhanced light-matter couplings. These techniques can be used to create the recently proposed quantum clock network based on neutral atom optical clocks. We specifically analyze a possible realization of this scheme using neutral Yb ensembles.

Heralded quantum gates with integrated error detection in optical cavities.

We propose and analyze heralded quantum gates between qubits in optical cavities. They employ an auxiliary qubit to report if a successful gate occurred. In this manner, the errors, which would have corrupted a deterministic gate, are converted into a nonunity probability of success: once successful, the gate has a much higher fidelity than a similar deterministic gate. Specifically, we describe that a heralded, near-deterministic controlled phase gate (CZ gate) with the conditional error arbitrarily close to zero and the success probability that approaches unity as the cooperativity of the system, C, becomes large. Furthermore, we describe an extension to near-deterministic N-qubit Toffoli gate with a favorable error scaling. These gates can be directly employed in quantum repeater networks to facilitate near-ideal entanglement swapping, thus greatly speeding up the entanglement distribution.

Heisenberg-limited atom clocks based on entangled qubits.

We present a quantum-enhanced atomic clock protocol based on groups of sequentially larger Greenberger-Horne-Zeilinger (GHZ) states that achieves the best clock stability allowed by quantum theory up to a logarithmic correction. Importantly the protocol is designed to work under realistic conditions where the drift of the phase of the laser interrogating the atoms is the main source of decoherence. The simultaneous interrogation of the laser phase with a cascade of GHZ states realizes an incoherent version of the phase estimation algorithm that enables Heisenberg-limited operation while extending the coherent interrogation time beyond the laser noise limit. We compare and merge the new protocol with existing state of the art interrogation schemes, and identify the precise conditions under which entanglement provides an advantage for clock stabilization: it allows a significant gain in the stability for short averaging time.

Optomechanical quantum information processing with photons and phonons.

We describe how strong resonant interactions in multimode optomechanical systems can be used to induce controlled nonlinear couplings between single photons and phonons. Combined with linear mapping schemes between photons and phonons, these techniques provide a universal building block for various classical and quantum information processing applications. Our approach is especially suited for nano-optomechanical devices, where strong optomechanical interactions on a single photon level are within experimental reach.

Comparison of pap smear quality with anatomical spatula method and the common method (spatula-cytobrush): a single blind clinical trial.

BACKGROUND: Cervical cancer is the third most common cancer in women in the world. Papanicolaou smear is known as a standard test for cervical cancer screening; however, the most important challenge is high rates of false negative results. The aim of this study was to compare the quality of smears obtained by anatomical spatula and spatula-cytobrush. The most important factor in false negative result is inappropriate tool of sampling. METHODS: One hundred married women participated in this single blind clinical trial. All participants were interviewed; two samples were obtained from every participant: one with spatula-cytobrush and another one with anatomical spatula. All slides were encoded and were assessed by two pathologists. Then, data were analyzed by means of kappa coefficient. RESULTS: Cell adequacy was 96.1 % in anatomical spatula method and 91.2 % in spatula-cytobrush method (p= 0.016). The rates for endocervical cells and metaplasia cells in anatomical spatula method were 70.6% and 24.5% respectively and these amounts were 69.6% and 24.5% respectively in the spatula-cytobrush method (p <0.001). No one reported any pain and the amount of bleeding was 38.2% in both methods (P>0.05). Regarding infection and inflammatory reactions there was no statistically significant difference between two methods (p>0.05). CONCLUSION: Based on our findings in this study, results of sampling with anatomical spatula method were more acceptable and better than those with spatula-cytobrush sampling.

[Ultrasound diagnosis of aneurysm of the vein of Galen in children]. / Diagnostika aneurizme Galenove vene metodom ultrazvuka kod dece.

Aneurysm of the vein of Galen is rare and complex vascular disorder that develops during embriogenesis and provokes significant haemodynamic changes. Boys are more frequently involved. During the foetal period Ballantyne syndrome may develop, and postnatal clinical presentation vary with ages. Serious haemodynamic changes are followed by congestive heart failure and, if not treated, with lethal exitus. Fast and correct diagnosis is very important. Ultrasound examination of central nervous system supported with Duplex-Doppler and Colour-Doppler examination of the head and heart enables the diagnosis. This text comments ultrasound presentation of the malformation and ultrasound diagnostic possibilities.

Focal glomerular sclerosis and nephrotic syndrome in spondyloepiphyseal dysplasia.

The association of a spondyloepiphyseal dysplasia and disproportionate short stature with focal glomerular sclerosis is reported in two girls. Renal disease manifested by proteinuria at the age of 2.5 and 11 years, leading to treatment-resistant nephrotic syndrome over 15 and 45 months, respectively. One patient went into end-stage renal failure shortly after nephrotic syndrome developed, the other died from sepsis. The association of spondyloepiphyseal dysplasia and focal glomerular sclerosis with nephrotic syndrome may represent a distinct disease entity.