20 research outputs found
Resonant Cooper-Pair Tunneling: Counting Statistics and Frequency-Dependent Current Noise
We discuss the counting statistics and current noise associated with the
double Josephson quasiparticle resonance point in a superconducting single
electron transistor. The counting statistics are in general phase-dependent,
despite the fact that the average current has no dependence on phase. Focusing
on parameter regimes where the counting statistics have no phase-dependence, we
use a general relation first derived by MacDonald in 1948 to obtain the full
frequency-dependent shot noise directly from the counting statistics, without
any further approximations. We comment on problems posed by the
phase-dependence of the counting statistics for the finite-frequency noise.Comment: 13 pages, 2 figures; to appear in the proceedings of the NATO ASI
"New Directions in Mesoscopic Physics", Erice, 200
Synthetic Spectrum Constraints on a Model of the Cataclysmic Variable QU Carinae
Neither standard model SEDs nor truncated standard model SEDs fit observed
spectra of QU Carinae with acceptable accuracy over the range 900\AA to
3000\AA. Non-standard model SEDs fit the observation set accurately. The
non-standard accretion disk models have a hot region extending from the white
dwarf to ,a narrow intermediate temperature annulus, and an
isothermal remainder to the tidal cutoff boundary. The models include a range
of values between and
and limiting values of
between and . A solution with is consistent with an empirical mass-period relation. The set
of models agree on a limited range of possible isothermal region
values between 14,000K and 18,000K. The model-to-model residuals are so similar
that it is not possible to choose a best model. The Hipparcos distance, 610 pc,
is representative of the model results. The orbital inclination is between
40\arcdeg and 60\arcdeg.Comment: 52 pages, 19 Figure
Microscopic study of freeze-out in relativistic heavy ion collisions at SPS energies
The freeze-out conditions in the light (S+S) and heavy (Pb+Pb) colliding
systems of heavy nuclei at 160 AGeV/ are analyzed within the microscopic
Quark Gluon String Model (QGSM). We found that even for the most heavy systems
particle emission takes place from the whole space-time domain available for
the system evolution, but not from the thin ''freeze-out hypersurface", adopted
in fluid dynamical models. Pions are continuously emitted from the whole volume
of the reaction and reflect the main trends of the system evolution. Nucleons
in Pb+Pb collisions initially come from the surface region. For both systems
there is a separation of the elastic and inelastic freeze-out. The mesons with
large transverse momenta, , are predominantly produced at the early stages
of the reaction. The low -component is populated by mesons coming mainly
from the decay of resonances. This explains naturally the decreasing source
sizes with increasing , observed in HBT interferometry. Comparison with
S+S and Au+Au systems at 11.6 AGeV/ is also presented.Comment: REVTEX, 26 pages incl. 9 figures and 2 tables, to be published in the
Physical Review
Coherent quantum state storage and transfer between two phase qubits via a resonant cavity
A network of quantum-mechanical systems showing long lived phase coherence of
its quantum states could be used for processing quantum information. As with
classical information processing, a quantum processor requires information bits
(qubits) that can be independently addressed and read out, long-term memory
elements to store arbitrary quantum states, and the ability to transfer quantum
information through a coherent communication bus accessible to a large number
of qubits. Superconducting qubits made with scalable microfabrication
techniques are a promising candidate for the realization of a large scale
quantum information processor. Although these systems have successfully passed
tests of coherent coupling for up to four qubits, communication of individual
quantum states between qubits via a quantum bus has not yet been demonstrated.
Here, we perform an experiment demonstrating the ability to coherently transfer
quantum states between two superconducting Josephson phase qubits through a
rudimentary quantum bus formed by a single, on chip, superconducting
transmission line resonant cavity of length 7 mm. After preparing an initial
quantum state with the first qubit, this quantum information is transferred and
stored as a nonclassical photon state of the resonant cavity, then retrieved at
a later time by the second qubit connected to the opposite end of the cavity.
Beyond simple communication, these results suggest that a high quality factor
superconducting cavity could also function as a long term memory element. The
basic architecture presented here is scalable, offering the possibility for the
coherent communication between a large number of superconducting qubits.Comment: 17 pages, 4 figures (to appear in Nature
Pion Interferometry in Au+Au Collisions at the Ags
Two-pion Bose-Einstein correlations have been studied using the BNL-E866 Forward Spectrometer in 11.6 A {center_dot} GeV/c Au + Au collisions. The data were analyzed using three-dimensional correlation parameterizations to study transverse momentum-dependent source parameters. The freeze-out time and the duration of emission were derived from the source radii parameters
Phospho-mTOR in non-tumour and tumour bladder urothelium : pattern of expression and impact on urothelial bladder cancer patients
Urothelial bladder carcinoma (UBC) is heterogeneous in its pathology and clinical behaviour. Evaluation of prognostic and predictive biomarkers is necessary, in order to produce personalised treatment options. The present study used immunohistochemistry to evaluate UBC sections containing tumour and non-tumour areas from 76 patients, for the detection of p-mTOR, CD31 and D2-40 (blood and lymphatic vessels identification, respectively). Of the non-tumour and tumour sections, 36 and 20% were scored positive for p-mTOR expression, respectively. Immunoexpression was observed in umbrella cells from non-tumour urothelium, in all cell layers from non-muscle-invasive (NMI) tumours (including expression in superficial cells), and in spots of cells from muscle-invasive (MI) tumours. Positive expression decreased from non-tumour to tumour urothelium, and from pT1/pTis to pT3/pT4 tumours; however, the few pT3/pT4 positive cases had worse survival rates, with 5-year disease-free survival being significantly lower. Angiogenesis occurrence was impaired in pT3/pT4 tumours that did not express p-mTOR. In conclusion, p-mTOR expression in non-tumour umbrella cells is likely a reflection of their metabolic plasticity, and extension to the inner layers of the urothelium in NMI tumours is consistent with an enhanced malignant potential. The expression in cell spots in a few MI tumours and absence of expression in the remaining tumours is intriguing and requires further research. Additional studies regarding the up- and downstream effectors of the mTOR pathway should be conducte
Two-particle BoseEinstein correlations in pp collisions at √s = 0.9 and 7 TeV measured with the ATLAS detector
The paper presents studies of Bose–Einstein Correlations (BEC) for pairs of like-sign charged particles measured in the kinematic range pT > 100 MeV and |η| <2.5 in proton–proton collisions at centre-of-mass energies of 0.9 and 7
TeV with the ATLAS detector at the CERN Large Hadron
Collider. The integrated luminosities are approximately 7
μb−1, 190 μb−1 and 12.4 nb-1 for 0.9 TeV,7 TeV minimum-bias and 7 TeV high-multiplicity data samples, respectively. The multiplicity dependence of the BEC parameters characterizing the correlation strength and the correlation source size are investigated for charged-particle multiplicities of up to 240. A saturation effect in the multiplicity dependence of the correlation source size parameter is observed using the high-multiplicity 7 TeV
data sample. The dependence of the BEC parameters on the average transverse momentum of the particle pair is also investigated