156 research outputs found
Where "God sleeps at night": Integration, Differentiation and Fragmentation in a Mennonite Colony
Practical quantum repeaters with linear optics and double-photon guns
We show how to create practical, efficient, quantum repeaters, employing
double-photon guns, for long-distance optical quantum communication. The guns
create polarization-entangled photon pairs on demand. One such source might be
a semiconducter quantum dot, which has the distinct advantage over parametric
down-conversion that the probability of creating a photon pair is close to one,
while the probability of creating multiple pairs vanishes. The swapping and
purifying components are implemented by polarizing beam splitters and
probabilistic optical CNOT gates.Comment: 4 pages, 4 figures ReVTe
Conditional linear-optical measurement schemes generate effective photon nonlinearities
We provide a general approach for the analysis of optical state evolution
under conditional measurement schemes, and identify the necessary and
sufficient conditions for such schemes to simulate unitary evolution on the
freely propagating modes. If such unitary evolution holds, an effective photon
nonlinearity can be identified. Our analysis extends to conditional measurement
schemes more general than those based solely on linear optics.Comment: 16 pages, 2 figure
Niet alle lelies goede waardplant voor wortellesieaaltjes
Het is algemeen bekend dat wortellesieaaltjes in lelie voor flinke schade kunnen zorgen en dat deze aaltjes zich bovendien op lelie goed kunnen vermeerderen. Of ligt het toch iets anders? PPO en PRI onderzochten nauwkeurig het verloop in de grond en het gewas
Teleportation-based number state manipulation with number sum measurement
We examine various manipulations of photon number states which can be
implemented by teleportation technique with number sum measurement. The
preparations of the Einstein-Podolsky-Rosen resources as well as the number sum
measurement resulting in projection to certain Bell state may be done
conditionally with linear optical elements, i.e., beam splitters, phase
shifters and zero-one-photon detectors. Squeezed vacuum states are used as
primary entanglement resource, while single-photon sources are not required.Comment: 9 pages, 4 figures, Misprints are corrected. 3 figures for number sum
measurement are added. Discussion on manipulations are expanded. Calculations
for success probabilities are added. Fig.4 is adde
Continuous-Variable Quantum Teleportation with a Conventional Laser
We give a description of balanced homodyne detection (BHD) using a
conventional laser as a local oscillator (LO), where the laser field outside
the cavity is a mixed state whose phase is completely unknown. Our description
is based on the standard interpretation of the quantum theory for measurement,
and accords with the experimental result in the squeezed state generation
scheme. We apply our description of BHD to continuous-variable quantum
teleportation (CVQT) with a conventional laser to analyze the CVQT experiment
[A. Furusawa et al., Science 282, 706 (1998)], whose validity has been
questioned on the ground of intrinsic phase indeterminacy of the laser field
[T. Rudolph and B.C. Sanders, Phys. Rev. Lett. 87, 077903 (2001)]. We show that
CVQT with a laser is valid only if the unknown phase of the laser field is
shared among sender's LOs, the EPR state, and receiver's LO. The CVQT
experiment is considered valid with the aid of an optical path other than the
EPR channel and a classical channel, directly linking between a sender and a
receiver. We also propose a method to probabilistically generate a strongly
phase-correlated quantum state via continuous measurement of independent
lasers, which is applicable to realizing CVQT without the additional optical
path.Comment: 5 pages, 2 figure
Quantum diffraction and interference of spatially correlated photon pairs generated by spontaneous parametric down-conversion
We demonstrate one- and two-photon diffraction and interference experiments
utilizing parametric down-converted photon pairs (biphotons) and a transmission
grating. With two-photon detection, the biphoton exhibits a
diffraction-interference pattern equivalent to that of an effective single
particle that is associated with half the wavelength of the constituent
photons. With one-photon detection, however no diffraction-interference pattern
is observed. We show that these phenomena originate from the spatial quantum
correlation between the down-converted photons.Comment: 4 pages, 5 figure
Modelling ponatinib resistance in tyrosine kinase inhibitor-naive and dasatinib resistant BCR-ABL1+ cell lines
TKI resistance remains a major impediment to successful treatment of CML. In this study, we investigated the emerging modes of ponatinib resistance in TKI-naïve and dasatinib resistant BCR-ABL1+ cell lines. To investigate potential resistance mechanisms, ponatinib resistance was generated in BCR-ABL1+ cell-lines by long-term exposure to increasing concentrations of ponatinib. Two cell lines with prior dasatinib resistance demonstrated BCR-ABL1 kinase domain (KD) mutation(s) upon exposure to ponatinib. In one of these cell lines the T315I mutation had emerged during dasatinib exposure. When further cultured with ponatinib, the T315I mutation level and BCR-ABL1 mRNA expression level were increased. In the other cell line, compound mutations G250E/E255K developed with ponatinib exposure. In contrast, the ponatinib resistant cell lines that had no prior exposure to other TKIs (TKI-naïve) did not develop BCR-ABL1 KD mutations. Rather, both of these cell lines demonstrated Bcr-Abl-independent resistance via Axl overexpression. Axl, a receptor tyrosine kinase, has previously been associated with imatinib and nilotinib resistance. Ponatinib sensitivity was restored following Axl inhibition or shRNA-mediated-knockdown of Axl, suggesting that Axl was the primary driver of resistance and a potential target for therapy in this setting.Liu Lu, Chung Hoow Kok, Verity Ann Saunders, Jueqiong Wang, Jennifer Anne McLean, Timothy Peter Hughes, and Deborah Lee Whit
Demonstration of Feed-Forward Control for Linear Optics Quantum Computation
One of the main requirements in linear optics quantum computing is the
ability to perform single-qubit operations that are controlled by classical
information fed forward from the output of single photon detectors. These
operations correspond to pre-determined combinations of phase corrections and
bit-flips that are applied to the post-selected output modes of
non-deterministic quantum logic devices. Corrections of this kind are required
in order to obtain the correct logical output for certain detection events, and
their use can increase the overall success probability of the devices. In this
paper, we report on the experimental demonstration of the use of this type of
feed-forward system to increase the probability of success of a simple
non-deterministic quantum logic operation from approximately 1/4 to 1/2. This
logic operation involves the use of one target qubit and one ancilla qubit
which, in this experiment, are derived from a parametric down-conversion photon
pair. Classical information describing the detection of the ancilla photon is
fed-forward in real-time and used to alter the quantum state of the output
photon. A fiber optic delay line is used to store the output photon until a
polarization-dependent phase shift can be applied using a high speed Pockels
cell
Conditional generation of arbitrary multimode entangled states of light with linear optics
We propose a universal scheme for the probabilistic generation of an
arbitrary multimode entangled state of light with finite expansion in Fock
basis. The suggested setup involves passive linear optics, single photon
sources, strong coherent laser beams, and photodetectors with single-photon
resolution. The efficiency of this setup may be greatly enhanced if, in
addition, a quantum memory is available.Comment: 7 pages, 5 figure
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