77 research outputs found
Steady State Entanglement in Cavity QED
We investigate steady state entanglement in an open quantum system,
specifically a single atom in a driven optical cavity with cavity loss and
spontaneous emission. The system reaches a steady pure state when driven very
weakly. Under these conditions, there is an optimal value for atom-field
coupling to maximize entanglement, as larger coupling favors a loss port due to
the cavity enhanced spontaneous emission. We address ways to implement
measurements of entanglement witnesses and find that normalized
cross-correlation functions are indicators of the entanglement in the system.
The magnitude of the equal time intensity-field cross correlation between the
transmitted field of the cavity and the fluorescence intensity is proportional
to the concurrence for weak driving fields.Comment: enhanced discussion, corrected formulas, title change, 1 added figur
Faraday spectroscopy of atoms confined in a dark optical trap
We demonstrate Faraday spectroscopy with high duty cycle and sampling rate
using atoms confined to a blue-detuned optical trap. Our trap consists of a
crossed pair of high-charge-number hollow laser beams, which forms a dark,
box-like potential. We have used this to measure transient magnetic fields in a
500-micron-diameter spot over a 400 ms time window with nearly unit duty cycle
at a 500 Hz sampling rate. We use these measurements to quantify and compensate
time-varying magnetic fields to ~10 nT per time sample.Comment: 6 pages, 8 figures Accepted in Phys. Rev.
Unusual cross-sectional imaging findings in hepatic peliosis
Abstract.: Hepatic peliosis is a rare entity that represents focal, multifocal, segmental, or diffuse dilatation of liver sinusoids. Hepatic peliosis is often associated with chronic wasting diseases but also has been reported in association with anabolic, contraceptive, or other hormonal treatment, and even in context with HIV-related bacterial infections. Hepatic peliosis is usually clinically unapparent and mostly found only during autopsy, but occasionally it may lead to diagnostic problems if detected radiologically since the imaging findings in hepatic peliosis are quite variable according to the variety of its possible histologic features as well as the possibility of additional hemorrhage. We present a case of hepatic peliosis associated with bronchial carcinoma that showed moderate centripetal enhancement during the portal-venous phase on CT, pronounced venous pooling on contrast enhanced T1-weighted images acquired during the hepatic-venous phase, and bright signal on T2-weighted images, thus mimicking in some way a capillary hemangioma. We also discuss some not yet described CT and MR features of this rare entity which should be included into the differential diagnosis of atypical liver lesions in patients with the above-mentioned condition
Magnetically-controlled velocity selection in a cold atom sample using stimulated Raman transitions
We observe velocity-selective two-photon resonances in a cold atom cloud in
the presence of a magnetic field. We use these resonances to demonstrate a
simple magnetometer with sub-mG resolution. The technique is particularly
useful for zeroing the magnetic field and does not require any additional laser
frequencies than are already used for standard magneto-optical traps. We verify
the effects using Faraday rotation spectroscopy.Comment: 5 pages, 6 figure
Enhanced Spontaneous Emission Into The Mode Of A Cavity QED System
We study the light generated by spontaneous emission into a mode of a cavity
QED system under weak excitation of the orthogonally polarized mode. Operating
in the intermediate regime of cavity QED with comparable coherent and
decoherent coupling constants, we find an enhancement of the emission into the
undriven cavity mode by more than a factor of 18.5 over that expected by the
solid angle subtended by the mode. A model that incorporates three atomic
levels and two polarization modes quantitatively explains the observations.Comment: 9 pages, 2 figures, to appear in May 2007 Optics Letter
Cold atom confinement in an all-optical dark ring trap
We demonstrate confinement of Rb atoms in a dark, toroidal optical
trap. We use a spatial light modulator to convert a single blue-detuned
Gaussian laser beam to a superposition of Laguerre-Gaussian modes that forms a
ring-shaped intensity null bounded harmonically in all directions. We measure a
1/e spin-relaxation lifetime of ~1.5 seconds for a trap detuning of 4.0 nm. For
smaller detunings, a time-dependent relaxation rate is observed. We use these
relaxation rate measurements and imaging diagnostics to optimize trap alignment
in a programmable manner with the modulator. The results are compared with
numerical simulations.Comment: 5 pages, 4 figure
High flux cold Rubidium atomic beam for strongly coupled Cavity QED
This paper presents a setup capable of producing a high-flux continuous beam
of cold rubidium atoms for cavity QED experiments in the regime of strong
coupling. A 2 MOT, loaded by rubidium getters in a dry film coated vapor
cell, fed a secondary moving-molasses MOT (MM-MOT) at a rate of 1.5 x
atoms/sec. The MM-MOT provided a continuous beam with tunable velocity. This
beam was then directed through the waist of a 280 m cavity resulting in a
Rabi splitting of more than +/- 10 MHz. The presence of sufficient number of
atoms in the cavity mode also enabled splitting in the polarization
perpendicular to the input. The cavity was in the strong coupling regime, with
parameters (g, , )/2 equal to (7, 3, 6)/ 2 MHz.Comment: Journal pape
Extended calibration range for prompt photon emission in ion beam irradiation
Monitoring the dose delivered during proton and carbon ion therapy is still a
matter of research. Among the possible solutions, several exploit the
measurement of the single photon emission from nuclear decays induced by the
irradiation. To fully characterize such emission the detectors need
development, since the energy spectrum spans the range above the MeV that is
not traditionally used in medical applications. On the other hand, a deeper
understanding of the reactions involving gamma production is needed in order to
improve the physic models of Monte Carlo codes, relevant for an accurate
prediction of the prompt-gamma energy spectrum.This paper describes a
calibration technique tailored for the range of energy of interest and
reanalyzes the data of the interaction of a 80MeV/u fully stripped carbon ion
beam with a Poly-methyl methacrylate target. By adopting the FLUKA simulation
with the appropriate calibration and resolution a significant improvement in
the agreement between data and simulation is reported.Comment: 4 pages, 7 figures, Submitted to JINS
Multicenter phase II trial of preoperative induction chemotherapy followed by chemoradiation with docetaxel and cisplatin for locally advanced esophageal carcinoma (SAKK 75/02)
Background: This multicenter phase II study investigated the efficacy and feasibility of preoperative induction chemotherapy followed by chemoradiation and surgery in patients with esophageal carcinoma. Patients and methods: Patients with locally advanced resectable squamous cell carcinoma or adenocarcinoma of the esophagus received induction chemotherapy with cisplatin 75 mg/m2 and docetaxel (Taxotere) 75 mg/m2 on days 1 and 22, followed by radiotherapy of 45 Gy (25 × 1.8 Gy) and concurrent chemotherapy comprising cisplatin 25 mg/m2 and docetaxel 20 mg/m2 weekly for 5 weeks, followed by surgery. Results: Sixty-six patients were enrolled at eleven centers and 57 underwent surgery. R0 resection was achieved in 52 patients. Fifteen patients showed complete, 16 patients nearly complete and 26 patients poor pathological remission. Median overall survival was 36.5 months and median event-free survival was 22.8 months. Squamous cell carcinoma and good pathologically documented response were associated with longer survival. Eighty-two percent of all included patients completed neoadjuvant therapy and survived for 30 days after surgery. Dysphagia and mucositis grade 3/4 were infrequent (<9%) during chemoradiation. Five patients (9%) died due to surgical complications. Conclusions: This neoadjuvant, taxane-containing regimen was efficacious and feasible in patients with locally advanced esophageal cancer in a multicenter, community-based setting and represents a suitable backbone for further investigatio
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