6,285 research outputs found
Synthesis of Quantum Logic Circuits
We discuss efficient quantum logic circuits which perform two tasks: (i)
implementing generic quantum computations and (ii) initializing quantum
registers. In contrast to conventional computing, the latter task is nontrivial
because the state-space of an n-qubit register is not finite and contains
exponential superpositions of classical bit strings. Our proposed circuits are
asymptotically optimal for respective tasks and improve published results by at
least a factor of two.
The circuits for generic quantum computation constructed by our algorithms
are the most efficient known today in terms of the number of expensive gates
(quantum controlled-NOTs). They are based on an analogue of the Shannon
decomposition of Boolean functions and a new circuit block, quantum
multiplexor, that generalizes several known constructions. A theoretical lower
bound implies that our circuits cannot be improved by more than a factor of
two. We additionally show how to accommodate the severe architectural
limitation of using only nearest-neighbor gates that is representative of
current implementation technologies. This increases the number of gates by
almost an order of magnitude, but preserves the asymptotic optimality of gate
counts.Comment: 18 pages; v5 fixes minor bugs; v4 is a complete rewrite of v3, with
6x more content, a theory of quantum multiplexors and Quantum Shannon
Decomposition. A key result on generic circuit synthesis has been improved to
~23/48*4^n CNOTs for n qubit
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Human Primordial Germ Cells Are Specified from Lineage-Primed Progenitors.
In vitro gametogenesis is the process of making germline cells from human pluripotent stem cells. The foundation of this model is the quality of the first progenitors called primordial germ cells (PGCs), which in vivo are specified during the peri-implantation window of human development. Here, we show that human PGC (hPGC) specification begins at day 12 post-fertilization. Using single-cell RNA sequencing of hPGC-like cells (hPGCLCs) differentiated from pluripotent stem cells, we discovered that hPGCLC specification involves resetting pluripotency toward a transitional state with shared characteristics between naive and primed pluripotency, followed by differentiation into lineage-primed TFAP2A+ progenitors. Applying the germline trajectory to TFAP2C mutants reveals that TFAP2C functions in the TFAP2A+ progenitors upstream of PRDM1 to regulate the expression of SOX17. This serves to protect hPGCLCs from crossing the Weismann's barrier to adopt somatic cell fates and, therefore, is an essential mechanism for successfully initiating in vitro gametogenesis
Revisiting LFSMs
Linear Finite State Machines (LFSMs) are particular primitives widely used in
information theory, coding theory and cryptography. Among those linear
automata, a particular case of study is Linear Feedback Shift Registers (LFSRs)
used in many cryptographic applications such as design of stream ciphers or
pseudo-random generation. LFSRs could be seen as particular LFSMs without
inputs.
In this paper, we first recall the description of LFSMs using traditional
matrices representation. Then, we introduce a new matrices representation with
polynomial fractional coefficients. This new representation leads to sparse
representations and implementations. As direct applications, we focus our work
on the Windmill LFSRs case, used for example in the E0 stream cipher and on
other general applications that use this new representation.
In a second part, a new design criterion called diffusion delay for LFSRs is
introduced and well compared with existing related notions. This criterion
represents the diffusion capacity of an LFSR. Thus, using the matrices
representation, we present a new algorithm to randomly pick LFSRs with good
properties (including the new one) and sparse descriptions dedicated to
hardware and software designs. We present some examples of LFSRs generated
using our algorithm to show the relevance of our approach.Comment: Submitted to IEEE-I
On the Information Engine of Circuit Design
This paper addresses a new approach to find a spectrum of information
measures for the process of digital circuit synthesis. We consider the problem
from the information engine point of view. The circuit synthesis as a whole and
different steps of the design process (an example of decision diagram is given)
are presented via such measurements as entropy, logical work and information
vitality. We also introduce new information measures to provide better
estimates of synthesis criteria. We show that the basic properties of
information engine, such as the conservation law of information flow and the
equilibrium law of information can be formulated.Comment: 4 pages, 1 figure, 2 tables, MWSCAS'0
Construction of dynamic stochastic simulation models using knowledge-based techniques
Over the past three decades, computer-based simulation models have proven themselves to be cost-effective alternatives to the more structured deterministic methods of systems analysis. During this time, many techniques, tools and languages for constructing computer-based simulation models have been developed. More recently, advances in knowledge-based system technology have led many researchers to note the similarities between knowledge-based programming and simulation technologies and to investigate the potential application of knowledge-based programming techniques to simulation modeling. The integration of conventional simulation techniques with knowledge-based programming techniques is discussed to provide a development environment for constructing knowledge-based simulation models. A comparison of the techniques used in the construction of dynamic stochastic simulation models and those used in the construction of knowledge-based systems provides the requirements for the environment. This leads to the design and implementation of a knowledge-based simulation development environment. These techniques were used in the construction of several knowledge-based simulation models including the Advanced Launch System Model (ALSYM)
Workflow resource pattern modelling and visualization
Workflow patterns have been recognized as the theoretical basis to modeling recurring problems in workflow systems. A form of workflow patterns, known as the resource patterns, characterise the behaviour of resources in workflow systems. Despite the fact that many resource patterns have been discovered, people still preclude them from many workflow system implementations. One of reasons could be obscurityin the behaviour of and interaction between resources and a workflow management system. Thus, we provide a modelling and visualization approach for the resource patterns, enabling a resource behaviour modeller to intuitively see the specific resource patterns involved in the lifecycle of a workitem. We believe this research can be extended to benefit not only workflow modelling, but also other applications, such as model validation, human resource behaviour modelling, and workflow model visualization
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