Experimental verification of the commutation relation for Pauli spin operators using single-photon quantum interference

We report experimental verification of the commutation relation for Pauli spin operators using quantum interference of the single-photon polarization state. By superposing the quantum operations $\sigma_z \sigma_x$ and $\sigma_x \sigma_z$ on a single-photon polarization state, we have experimentally implemented the commutator, $[\sigma_{z}, \sigma_{x}]$, and the anticommutator, $\{\sigma_{z}, \sigma_{x}\}$, and have demonstrated the relative phase factor of $\pi$ between $\sigma_z \sigma_x$ and $\sigma_x \sigma_z$ operations. The experimental quantum operation corresponding to the commutator, $[\sigma_{z}, \sigma_{x}]=k\sigma_y$, showed process fidelity of 0.94 compared to the ideal $\sigma_y$ operation and $|k|$ is determined to be $2.12\pm0.18$.Comment: 4pages, 3 figure

Reversing the Weak Quantum Measurement for a Photonic Qubit

We demonstrate the conditional reversal of a weak (partial-collapse) quantum measurement on a photonic qubit. The weak quantum measurement causes a nonunitary transformation of a qubit which is subsequently reversed to the original state after a successful reversing operation. Both the weak measurement and the reversal operation are implemented linear optically. The state recovery fidelity, determined by quantum process tomography, is shown to be over 94% for partial-collapse strength up to 0.9. We also experimentally study information gain due to the weak measurement and discuss the role of the reversing operation as an information erasure

Realizing Physical Approximation of the Partial Transpose

The partial transpose by which a subsystem's quantum state is solely transposed is of unique importance in quantum information processing from both fundamental and practical point of view. In this work, we present a practical scheme to realize a physical approximation to the partial transpose using local measurements on individual quantum systems and classical communication. We then report its linear optical realization and show that the scheme works with no dependence on local basis of given quantum states. A proof-of-principle demonstration of entanglement detection using the physical approximation of the partial transpose is also reported.Comment: 5 pages with appendix, 3 figure

Experimental Implementation of the Universal Transpose Operation

The universal transpose of quantum states is an anti-unitary transformation that is not allowed in quantum theory. In this work, we investigate approximating the universal transpose of quantum states of two-level systems (qubits) using the method known as the structural physical approximation to positive maps. We also report its experimental implementation in linear optics. The scheme is optimal in that the maximal fidelity is attained and also practical as measurement and preparation of quantum states that are experimentally feasible within current technologies are solely applied.Comment: 4 pages, 4 figure

Plastic Shrinkage Properties of Natural Fiber Reinforced Shotcrete

Recently, natural hemp fibers have been developed for use in wet or dry mix shotcrete instead of conventional synthetic fibers made from petroleum. Synthetic fibers, which is mainly in polypropylene, has been used for controlling an initial shrinkage cracking in concrete, however, the effect was poor showing a severe plastic shrinkage cracking. Plastic shrinkage cracking is a nonstructural crack that occurs due to the surface drying of concrete in a plastic condition due to rapid evaporation of bleeding water. The volume reduction due to plastic shrinkage and the resulting tensile stress exceeds the tensile strength of the concrete. In particular, plastic shrinkage cracking occurs mainly in large surface area members. It may be evolved from the surface to a considerable depth, or in the case of a very thin structure, it may go all over the depth of the member. In addition, since it is long enough to be easily distinguished by naked eyes and cracks are generated widely, it is not aesthetically pleasing and anxiety about the stability of the concrete can be increased. Also, the plastic shrinkage crack accelerates penetration of chloride and moisture, causing corrosion of the reinforcing bar, and durability of the concrete is lowered. The theoretical effect of natural fibers on plastic shrinkage cracks is that when natural fibers are mixed into concrete, they become wet by absorbing the water. Then, in the pumping, water in the wet natural fiber is supplied to the concrete by the pumping pressure to increase the pumpability. Re-absorbing the water after spraying increases the adhesion and build-up thickness. The absorbed water could be supplied to the shotcrete and resulted in reducing a plastic shrinkage and dry shrinkage. This paper investigates the plastic shrinkage properties of shotcrete containing natural fibers. A series of experimental program were conducted to analysis the theoretical background and to select the optimized natural fiber content

Epidemiology and Investigation of Foot‐and‐Mouth Disease (FMD) in the Republic of Korea

This chapter describes about the experience of dealing with FMD outbreaks in the Republic of Korea. We explain what is FMD, the concept of epidemiological investigation on outbreak sites of FMD, including the episode of detecting the index case for seven epidemics occurred since 2000, and information obtained from investigation in Korea. In any case, farmers’ attitude (recognize clinical signs and report suspected cases) played the essential role in determining size and duration of epidemics. A rapid and correct diagnosis including clinical examination and laboratory test for confirmation is also important

Phosphorus in the Young Supernova Remnant Cassiopeia A

Phosphorus (^(31)P), which is essential for life, is thought to be synthesized in massive stars and dispersed into interstellar space when these stars explode as supernovae (SNe). Here, we report on near-infrared spectroscopic observations of the young SN remnant Cassiopeia A, which show that the abundance ratio of phosphorus to the major nucleosynthetic product iron (^(56)Fe) in SN material is up to 100 times the average ratio of the Milky Way, confirming that phosphorus is produced in SNe. The observed range is compatible with predictions from SN nucleosynthetic models but not with the scenario in which the chemical elements in the inner SN layers are completely mixed by hydrodynamic instabilities during the explosion