24 research outputs found
Optimal cloning of single photon polarization by coherent feedback of beam splitter losses
Light fields can be amplified by measuring the field amplitude reflected at a
beam splitter of reflectivity R and adding a coherent amplitude proportional to
the measurement result to the transmitted field. By applying the quantum
optical realization of this amplification scheme to single photon inputs, it is
possible to clone the polarization states of photons. We show that optimal
cloning of single photon polarization is possible when the gain factor of the
amplification is equal to the inverse squareroot of 1-R.Comment: 10 pages, including 1 figure, extended from letter to full paper, to
be published in New Journal of Physic
Gain tuning and fidelity in continuous variable quantum teleportation
The fidelity of continuous variable teleportation can be optimized by
changing the gain in the modulation of the output field. We discuss the gain
dependence of fidelity for coherent, vacuum and one photon inputs and propose
optimal gain tuning strategies for corresponding input selections.Comment: 23 pages, 10 figure
Information extraction and quantum state distortions in continuous variable quantum teleportation
We analyze the loss of fidelity in continuous variable teleportation due to
non-maximal entanglement. It is shown that the quantum state distortions
correspond to the measurement back-action of a field amplitude measurement.
Results for coherent states and for photon number states are presented.Comment: 4 pages Latex, contribution to the proceedings of the ISQM'01
conference held August 27th to 30th in Toky
Fidelity and information in the quantum teleportation of continuous variables
Ideally, quantum teleportation should transfer a quantum state without
distortion and without providing any information about that state. However,
quantum teleportation of continuous electromagnetic field variables introduces
additional noise, limiting the fidelity of the quantum state transfer. In this
article, the operator describing the quantum state transfer is derived. The
transfer operator modifies the probability amplitudes of the quantum state in a
shifted photon number base by enhancing low photon numbers and suppressing high
photon numbers. This modification of the statistical weight corresponds to a
measurement of finite resolution performed on the original quantum state. The
limited fidelity of quantum teleportation is thus shown to be a direct
consequence of the information obtained in the measurement.Comment: 10 pages, including one figure, minor clarifications and added
referenc
Continuous variable teleportation of single photon states
The properties of continuous variable teleportation of single photon states
are investigated. The output state is different from the input state due to the
non-maximal entanglement in the EPR beams. The photon statistics of the
teleportation output are determined and the correlation between the field
information beta obtained in the teleportation process and the change in photon
number is discussed. The results of the output photon statistics are applied to
the transmission of a qbit encoded in the polarization of a single photon.Comment: 14 pages, including 6 figure
TTC26/DYF13 is an intraflagellar transport protein required for transport of motility-related proteins into flagella
Cilia/flagella are assembled and maintained by the process of intraflagellar transport (IFT), a highly conserved mechanism involving more than 20 IFT proteins. However, the functions of individual IFT proteins are mostly unclear. To help address this issue, we focused on a putative IFT protein TTC26/DYF13. Using live imaging and biochemical approaches we show that TTC26/DYF13 is an IFT complex B protein in mammalian cells and Chlamydomonas reinhardtii. Knockdown of TTC26/DYF13 in zebrafish embryos or mutation of TTC26/DYF13 in C. reinhardtii, produced short cilia with abnormal motility. Surprisingly, IFT particle assembly and speed were normal in dyf13 mutant flagella, unlike in other IFT complex B mutants. Proteomic and biochemical analyses indicated a particular set of proteins involved in motility was specifically depleted in the dyf13 mutant. These results support the concept that different IFT proteins are responsible for different cargo subsets, providing a possible explanation for the complexity of the IFT machinery. DOI: http://dx.doi.org/10.7554/eLife.01566.00
Information losses in continuous-variable quantum teleportation
It is shown that the information losses due to the limited fidelity of continuous variable quantum teleportation are equivalent to the losses induced by a beam splitter of appropriate reflectivity