Analysis of N-qubit Perfect Controlled Teleportation Schemes from the Controller\u27s Point of View

We quantitatively analyze and evaluate the controller\u27s power in N-qubit controlled teleportation schemes. We calculate the minimum control power required to ensure the controller\u27s authority such that the teleportation fidelity without the controller\u27s permission is no more than the classical bound. We revisit several typical controlled teleportation schemes from the controller\u27s point of view and evaluate the control power in these schemes. We find that for teleporting arbitrary N-qubit states, each controller should control at least N bits of useful information to ensure his or her authority over the protocol. We also discuss the general rules that must be satisfied by controlled teleportation schemes to ensure both teleportation fidelity and control power

Control power in perfect controlled teleportation via partially entangled channels

We analyze and evaluate perfect controlled teleportation via three-qubit entangled channels from the point of view of the controller. The key idea in controlled teleportation is that the teleportation is performed only with the participation of the controller. We calculate a quantitative measure of the controller's power and establish a lower bound on the control power required for controlled teleportation. We show that the maximally entangled GHZ state is a suitable channel for controlled teleportation of arbitrary single qubits - the controller's power meets the bound and the teleportation fidelity without the controller's permission is no better than the fidelity of a classical channel. We also construct partially entangled channels that exceed the bound for controlled teleportation of a restricted set of states called the equatorial states. We calculate the minimum entanglement required in these channels to exceed the bound. Moreover, we find that in these restricted controlled teleportation schemes, the partially entangled channels can outperform maximally entangled channels with respect to the controller's power. Our results provide a new perspective on controlled teleportation schemes and are of practical interest since we propose useful partially entangled channels.Comment: 5 page, Physical Review A 201

Determining the nature of white dwarfs from low-frequency gravitational waves

An extreme-mass-ratio system composed of a white dwarf (WD) and a massive black hole can be observed by the low-frequency gravitational wave detectors, such as the Laser Interferometer Space Antenna (LISA). When the mass of the black hole is around $10^4 \sim 10^5 M_\odot$, the WD will be disrupted by the tidal interaction at the final inspiraling stage. The event position and time of the tidal disruption of the WD can be accurately determined by the gravitational wave signals. Such position and time depend upon the mass of the black hole and especially on the density of the WD. We present the theory by using LISA-like gravitational wave detectors, the mass-radius relation and then the equations of state of WDs could be strictly constrained (accuracy up to $0.1\%$). We also point out that LISA can accurately predict the disruption time of a WD, and forecast the electromagnetic follow-up of this tidal disruption event.Comment: 7 pages, 2 figure

Particle engineering via surface modification during micronization for pharmaceutical applications

Improving the dissolution rate of Biopharmaceutics Classification System (BCS) class II drugs is an important research area. Micronization which can increase the specific surface area is a promising method to improve the dissolution rate. Micronization alone, however, can lead to downstream processing problems related to poor flow and dispersion properties. The importance of the flowability of pharmaceutical powders is well-documented in the literature. It is, therefore, important to develop a method that can simultaneously overcome these processing issues and allow for micronizing the API. In this work, dry particle coating technique is investigated in the context of micronizing API powders and overcoming problems associated with the micronized fine powders due to their strong cohesive forces. Consequently, the main objective of this dissertation is to investigate if simultaneous micronization and dry coating process (SM-DC) is beneficial for pharmaceutical applications. The work addresses and answers several important issues as discussed next. First, using ibuprofen as a test-case, it is shown that flow properties and dissolution rate were significantly improved when micronization was performed along with dry coating (SM-DC process). Additionally, co-grinding with water-soluble polymer during micronization was considered and led to further dissolution rate improvement and increased bulk density. The surface modified, micronized powders also showed improved dispersion, significantly higher bulk densities, reduced electrostatic charging, and higher flowability compared to the pure micronized sample. Next, these dry coated fine API powders were formulated into blends with different API loadings. The results showed that the blends containing dry coated API powders had excellent flowability and high bulk density. In contrast, blends containing uncoated APIs had poor flow and lower bulk densities. As the API loading increased, the difference between dry coated and uncoated blends was more pronounced. Tablets prepared from dry coated API blends exhibited superior compactibility and dissolution profiles, particularly for higher drug loadings. This illustrated the advantages of the dry coating during API micronization, without any adverse impact on tabletting operations and tablet properties. Next, an in-depth understanding of the effect of milling and dry coating on the surface properties of milled ibuprofen powders was investigated. Inverse Gas Chromatography technique was used and the dispersive surface energy of pure milled powders was heterogeneous in nature. In contrast, dry coating with nano-particles was found to quench the high energy sites and make the surface energy of the powders comparatively uniform and the average values similar to that of the nano-particle used for the dry coating. Last, a simple shear test based method was developed to estimate the granular Bond number to evaluate the performance of dry coating. This technique eliminates the usual need of detailed, time consuming particle scale characterization via atomic force microscopy. Estimated Bond numbers were compared and verified with those calculated from IGC method. Further, estimated Bond number was correlated with the bulk flow properties. The overall effect of dry coating (changing both the surface energy and nano-scale asperities) can be well demonstrated using the estimated Bond numbers. By addressing these four issues, the main hypothesis of the thesis, dry coating applied to the micronization process is beneficial to the pharmaceutical application, is proven