363 research outputs found
High-fidelity teleportation beyond the no-cloning limit and entanglement swapping for continuous variables
We experimentally demonstrate continuous-variable quantum teleportation
beyond the no-cloning limit. We teleport a coherent state and achieve the
fidelity of 0.700.02 that surpasses the no-cloning limit of 2/3.
Surpassing the limit is necessary to transfer the nonclassicality of an input
quantum state. By using our high-fidelity teleporter, we demonstrate
entanglement swapping, namely teleportation of quantum entanglement, as an
example of transfer of nonclassicality.Comment: revised version, 4 pages, 4 figure
Light-cone Gauge NSR Strings in Noncritical Dimensions
Light-cone gauge NSR string theory in noncritical dimensions should
correspond to a string theory with a nonstandard longitudinal part.
Supersymmetrizing the bosonic case [arXiv:0909.4675], we formulate a
superconformal worldsheet theory for the longitudinal variables X^{\pm},
\psi^{\pm}. We show that with the transverse variables and the ghosts combined,
it is possible to construct a nilpotent BRST charge.Comment: 22 pages, 1 figur
Noncommutative Yang-Mills in IIB Matrix Model
We show that twisted reduced models can be interpreted as noncommutative
Yang-Mills theory. Based upon this correspondence, we obtain noncommutative
Yang-Mills theory with D-brane backgrounds in IIB matrix model. We propose that
IIB matrix model with D-brane backgrounds serve as a concrete definition of
noncommutative Yang-Mills. We investigate D-instanton solutions as local
excitations on D3-branes. When instantons overlap, their interaction can be
well described in gauge theory and AdS/CFT correspondence. We show that IIB
matrix model gives us the consistent potential with IIB supergravity when they
are well separated.Comment: 21pages, LaTeX, no figures, typos correcte
Experimental verification of a fully inseparable tripartite continuous-variable state
A continuous-variable tripartite entangled state is experimentally generated
by combining three independent squeezed vacuum states and the variances of its
relative positions and total momentum are measured. We show that the measured
values violate the separability criteria based on the sum of these quantities
and prove the full inseparability of the generated state.Comment: 5 pages, 4 figure
A method for finding the background potential of quantum devices from scanning gate microscopy data using machine learning
The inverse problem of estimating the background potential from measurements of the local density of states is a challenging issue in quantum mechanics. Even more difficult is to do this estimation using approximate methods such as scanning gate microscopy (SGM). Here, we propose a machine-learning-based solution by exploiting adaptive cellular neural networks (CNNs). In the paradigmatic setting of a quantum point contact, the training data consist of potential-SGM functional relations represented by image pairs. These are generated by the recursive Green’s function method. We demonstrate that the CNN-based machine learning framework can predict the background potential corresponding to the experimental image data. This is confirmed by analyzing the estimated potential with image processing techniques based on the comparison between the charge densities and those obtained using different techniques. Correlation analysis of the images suggests the possibility of estimating different contributions to the background potential. In particular, our results indicate that both charge puddles and fixed impurities contribute to the spatial patterns found in the SGM data. Our work represents a timely contribution to the rapidly evolving field of exploiting machine learning to solve difficult problems in physics
Improved scientific ballooning applied to the cryo-sampling experiment at Syowa Station
On January 3, 1998, a large balloon (30000 m^3) was successfully launched at Syowa Station for the cryo-sampling of the stratospheric atmosphere. The sampling system splashed down in the Liitzow-Holm Bay and recovered by icebreaker SHIRASE. The cryo-sampling at Antarctica was the first trial in the world and the recovery of a heavy payload was also the first challenge at Syowa Station. A lot of new ballooning technologies were applied to this operation, such as compact balloon launching equipments, a reliable recovery system, a handy ground radio station for the balloon tracking and data acquisition and so forth. The realtime flight data could be received at National Institute of Polar Research (NIPR) in Tokyo by using the computer network via INMARSAT. At NIPR the collaboration members could monitor the entire process of the experiment at Syowa Station in detail and send some instructions and advice. This balloon experiment showed an extended possibility of a large scale scientific ballooning at Syowa Station. This paper deals with those newly developed balloon engineering technologies
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