Efficient Quantum Polar Coding

Polar coding, introduced 2008 by Arikan, is the first (very) efficiently encodable and decodable coding scheme whose information transmission rate provably achieves the Shannon bound for classical discrete memoryless channels in the asymptotic limit of large block sizes. Here we study the use of polar codes for the transmission of quantum information. Focusing on the case of qubit Pauli channels and qubit erasure channels, we use classical polar codes to construct a coding scheme which, using some pre-shared entanglement, asymptotically achieves a net transmission rate equal to the coherent information using efficient encoding and decoding operations and code construction. Furthermore, for channels with sufficiently low noise level, we demonstrate that the rate of preshared entanglement required is zero.Comment: v1: 15 pages, 4 figures. v2: 5+3 pages, 3 figures; argumentation simplified and improve

Design and microfabrication of a high-aspect-ratio PDMS microbeam array for parallel nanonewton force measurement and protein printing

Journal of Micromechanics and Microengineering, 17(3): pp. 623-632.Cell and protein mechanics has applications ranging from cellular development to tissue engineering. Techniques such as magnetic tweezers, optic tweezers, and atomic force microscopy have been used to measure cell deformation forces on the order of piconewtons to nanonewtons. In this study, an array of polymeric polydimethylsiloxane (PDMS) microbeams with diameters of 10-40μm and lengths of 118μm was fabricated from Sylgard® with curing agent concentrations ranging from 5% to 20%. Resulting spring constants were 100-300nN/μm. The elastic modulus of PDMS was determined experimentally at different curing agent concentrations and found to be 346kPa to 704kPa in a millimeter-scale array and ~1MPa in a microbeam array. Additionally, the microbeam array was used to print laminin for the purpose of cell adhesion. Linear and non-linear finite element analyses are presented and compared to the closed-from solution. Conclusion: The highly compliant, transparent, biocompatible PDMS may offer a method for more rapid throughput in cell and protein mechanics force measurement experiments with sensitivities necessary for highly compliant structures such as axons

Microfabrication procedure of PDMS microbeam array using photolithography for laminin printing and piconewton force transduction on axons

Paper presented at 28th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBS), New York, NY: Aug 30 - Sept 3, 2006.The purpose of this paper is to introduce our design for transducing forces on the order of tens of piconewtons by optically measuring deflection of a microfabricated beam tip as it pulls on an array of flexible structures such as axons in an array of lamininprinted neurons. To achieve this we have designed polymeric beams with spring constants on the order of 10pN/μm. We have fabricated circular microbeams with Sylgard® polydimethylsiloxane (PDMS). The elastic modulus of PDMS was determined experimentally using a microscale and a micrometer at different concentrations of curing agent and base agent and found to be on the order of 100kPa. The designed geometry is a 100x100 tapered microcone array with each beam having a length of 100μm, and a base diameter of 10 μm. A SU-8 negative photoresist is etched using photolithography and used as a mold for PDMS soft lithography. PDMS was injected into the mold and the array peeled from the mold

Towards a method for printing a network of chick forebrain neurons for biosensor applications

Paper presented at the 29th Annual International Conference of IEEE-EMBS, Engineering in Medicine and Biology Society, EMBC'07, Lyon, France.The primary goal of this work is to establish a robust, repeatable method for printing arrays of neurons. This work has two endpoints. One is to use a neural array as an experimental testbed for investigating neuronal cell growth hypotheses. The other endpoint is to enable the next generation of cell-based sensors. Herein we compare microcontact printing results previously published by our group with a new method of dip-pen printing. We present preliminary results for neurons growing on these microprinted arrays, assessing contact frequencies and growth characteristics

College of Engineering Drexel E-Repository and Archive (iDEA)

www.library.drexel.edu The following item is made available as a courtesy to scholars by the author(s) and Drexel University Library and may contain materials and content, including computer code and tags, artwork, text, graphics, images, and illustrations (Material) which may be protected by copyright law. Unless otherwise noted, the Material is made available for non profit and educational purposes, such as research, teaching and private study. For these limited purposes, you may reproduce (print, download or make copies) the Material without prior permission. All copies must include any copyright notice originally included with the Material. You must seek permission from the authors or copyright owners for all uses that are not allowed by fair use and other provisions of the U.S. Copyright Law. The responsibility for making an independent legal assessment and securing any necessary permission rests with persons desiring to reproduce or use the Material. Please direct questions to [email protected] F M Sasoglu, A J Bohl and B E Layton Microbeam array for nN force measurement Design and microfabrication a high-aspect-ratio PDMS microbeam array for parallel nanonewton force measurement and protein printin

Single-photon-multi-layer-interference lithography for high-aspect-ratio and three-dimensional SU-8 micro-/nanostructures

We report microstructures of SU-8 photo-sensitive polymer with high-aspect-ratio, which is defined as the ratio of height to in-plane feature size. The highest aspect ratio achieved in this work exceeds 250. A multi-layer and single-photon lithography approach is used in this work to expose SU-8 photoresist of thickness up to 100 μm. Here, multi-layer and time-lapsed writing is the key concept that enables nanometer localised controlled photo-induced polymerisation. We use a converging monochromatic laser beam of 405 nm wavelength with a controllable aperture. The reflection of the converging optics from the silicon substrate underneath is responsible for a trapezoidal edge profile of SU-8 microstructure. The reflection induced interfered point-spread-function and multi-layer-single-photon exposure helps to achieve sub-wavelength feature sizes. We obtained a 75 nm tip diameter on a pyramid shaped microstructure. The converging beam profile determines the number of multiple optical focal planes along the depth of field. These focal planes are scanned and exposed non-concurrently with varying energy dosage. It is notable that an un-automated height axis control is sufficient for this method. All of these contribute to realising super-high-aspect-ratio and 3D micro-/nanostructures using SU-8. Finally, we also address the critical problems of photoresist-based micro-/nanofabrication and their solutions

Molecular Modeling of the Axial and Circumferential Elastic Moduli of Tubulin

Microtubules play a number of important mechanical roles in almost all cell types in nearly all major phylogenetic trees. We have used a molecular mechanics approach to perform tensile tests on individual tubulin monomers and determined values for the axial and circumferential moduli for all currently known complete sequences. The axial elastic moduli, in vacuo, were found to be 1.25 GPa and 1.34 GPa for α- and β-bovine tubulin monomers. In the circumferential direction, these moduli were 378 MPa for α- and 460 MPa for β-structures. Using bovine tubulin as a template, 269 homologous tubulin structures were also subjected to simulated tensile loads yielding an average axial elastic modulus of 1.10 ± 0.14 GPa for α-tubulin structures and 1.39 ± 0.68 GPa for β-tubulin. Circumferentially the α- and β-moduli were 936 ± 216 MPa and 658 ± 134 MPa, respectively. Our primary finding is that that the axial elastic modulus of tubulin diminishes as the length of the monomer increases. However, in the circumferential direction, no correlation exists. These predicted anisotropies and scale dependencies may assist in interpreting the macroscale behavior of microtubules during mitosis or cell growth. Additionally, an intergenomic approach to investigating the mechanical properties of proteins may provide a way to elucidate the evolutionary mechanical constraints imposed by nature upon individual subcellular components