3,662 research outputs found
Measuring the parity of an -qubit state
We present a scheme for a projective measurement of the parity operator
of -qubits. Our protocol uses a single
ancillary qubit, or a probe qubit, and involves manipulations of the total spin
of the qubits without requiring individual addressing. We illustrate our
protocol in terms of an experimental implementation with atomic ions in a
two-zone linear Paul trap, and further discuss its extensions to several more
general cases.Comment: 4 pages, 2 figure
Dynamics of one-dimensional tight-binding models with arbitrary time-dependent external homogeneous fields
The exact propagators of two one-dimensional systems with time-dependent
external fields are presented by following the path-integral method. It is
shown that the Bloch acceleration theorem can be generalized to the
impulse-momentum theorem in quantum version. We demonstrate that an evolved
Gaussian wave packet always keeps its shape in an arbitrary time-dependent
homogeneous driven field. Moreover, that stopping and accelerating of a wave
packet can be achieved by the pulsed field in a diabatic way.Comment: 8 pages, 6 figure
Few-photon imaging at 1550 nm using a low-timing-jitter superconducting nanowire single-photon detector
We demonstrated a laser depth imaging system based on the time-correlated
single-photon counting technique, which was incorporated with a low-jitter
superconducting nanowire single-photon detector (SNSPD), operated at the
wavelength of 1550 nm. A sub-picosecond time-bin width was chosen for photon
counting, resulting in a discrete noise of less than one/two counts for each
time bin under indoor/outdoor daylight conditions, with a collection time of 50
ms. Because of the low-jitter SNSPD, the target signal histogram was
significantly distinguishable, even for a fairly low retro-reflected photon
flux. The depth information was determined directly by the highest bin counts,
instead of using any data fitting combined with complex algorithms. Millimeter
resolution depth imaging of a low-signature object was obtained, and more
accurate data than that produced by the traditional Gaussian fitting method was
generated. Combined with the intensity of the return photons, three-dimensional
reconstruction overlaid with reflectivity data was realized.Comment: 7 pages, 9 figure
Decoherence in a single trapped ion due to engineered reservoir
The decoherence in trapped ion induced by coupling the ion to the engineered
reservoir is studied in this paper. The engineered reservoir is simulated by
random variations in the trap frequency, and the trapped ion is treated as a
two-level system driven by a far off-resonant plane wave laser field. The
dependence of the decoherence rate on the amplitude of the superposition state
is given.Comment: 4 pages, 2 figure
Latexin sensitizes leukemogenic cells to gamma-irradiation-induced cell-cycle arrest and cell death through Rps3 pathway
Leukemia is a leading cause of cancer death. Recently, the latexin (Lxn) gene was identified as a potential tumor suppressor in several types of solid tumors and lymphoma, and Lxn expression was found to be absent or downregulated in leukemic cells. Whether Lxn functions as a tumor suppressor in leukemia and what molecular and cellular mechanisms are involved are unknown. In this study, the myeloid leukemogenic FDC-P1 cell line was used as a model system and Lxn was ectopically expressed in these cells. Using the protein pull-down assay and mass spectrometry, ribosomal protein subunit 3 (Rps3) was identified as a novel Lxn binding protein. Ectopic expression of Lxn inhibited FDC-P1 growth in vitro. More surprisingly, Lxn enhanced gamma irradiation-induced DNA damages and induced cell-cycle arrest and massive necrosis, leading to depletion of FDC-P1 cells. Mechanistically, Lxn inhibited the nuclear translocation of Rps3 upon radiation, resulting in abnormal mitotic spindle formation and chromosome instability. Rps3 knockdown increased the radiation sensitivity of FDC-P1, confirming that the mechanism of action of Lxn is mediated by Rps3 pathway. Moreover, Lxn enhanced the cytotoxicity of chemotherapeutic agent, VP-16, on FDC-P1 cells. Our study suggests that Lxn itself not only suppresses leukemic cell growth but also potentiates the cytotoxic effect of radio- and chemotherapy on cancer cells. Lxn could be a novel molecular target that improves the efficacy of anti-cancer therapy
A new spectrometer using multiple gratings with a two-dimensional charge-coupled diode array detector
A new spectrometer with no moving parts uses a two-dimensional Si-based charge-coupled diode (CCD) array detector and an integrated grating consisting of three subgratings. The effective spectral range imaged on the detector is magnified threefold. The digitized spectral image in the 200–1000 nm wavelength range can be measured quickly. The nonlinear relationship between CCD pixel position and wavelength is corrected with multiple polynomial functions in the calibration procedure, which fits the data using a mathematical pattern-analysis method. The instrument can be applied for rapid spectroscopicdata analyses in many types of photoelectronic experiments and routine testing
SUSY QCD impact on top-pair production associated with a -boson at a photon-photon collider
The top-pair production in association with a -boson at a photon-photon
collider is an important process in probing the coupling between top-quarks and
vector boson and discovering the signature of possible new physics. We describe
the impact of the complete supersymmetric QCD(SQCD) next-to-leading order(NLO)
radiative corrections on this process at a polarized or unpolarized photon
collider, and make a comparison between the effects of the SQCD and the
standard model(SM) QCD. We investigate the dependence of the lowest-order(LO)
and QCD NLO corrected cross sections in both the SM and minimal supersymmetric
standard model(MSSM) on colliding energy in different polarized
photon collision modes. The LO, SM NLO and SQCD NLO corrected distributions of
the invariant mass of -pair and the transverse momenta of final
-boson are presented. Our numerical results show that the pure SQCD
effects in \ggttz process can be more significant in the polarized photon
collision mode than in other collision modes, and the relative SQCD radiative
correction in unpolarized photon collision mode varies from 32.09% to
when goes up from to .Comment: 22 pages and 13 figure
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