Synchronously-pumped OPO coherent Ising machine: benchmarking and prospects

The coherent Ising machine (CIM) is a network of optical parametric oscillators (OPOs) that solves for the ground state of Ising problems through OPO bifurcation dynamics. Here, we present experimental results comparing the performance of the CIM to quantum annealers (QAs) on two classes of NP-hard optimization problems: ground state calculation of the Sherrington-Kirkpatrick (SK) model and MAX-CUT. While the two machines perform comparably on sparsely-connected problems such as cubic MAX-CUT, on problems with dense connectivity, the QA shows an exponential performance penalty relative to CIMs. We attribute this to the embedding overhead required to map dense problems onto the sparse hardware architecture of the QA, a problem that can be overcome in photonic architectures such as the CIM

Bringing the Good Food Purchasing Program to Buffalo, Challenges and Lessons Learned

The Good Food Purchasing Program (GFPP) builds on locally established community initiatives and goals to leverage institutional purchasing with the hope of transforming the food system. The program focuses on five core values: local economies, nutrition, a valued workforce, environmental sustainability, and animal welfare. The City of Buffalo shows tremendous potential to benefit from the GFPP. In the Buffalo Niagara region alone, “public institutions feed 163,000 public school students, 89,000 college students, and 6,000 correctional facility inmates each year—a total of 258,000 people.” Los Angeles, California has demonstrated the positive effects that the GFPP has had on the local food system. In order to bring the program to the City of Buffalo a better understanding of the program is necessary. The goal of this report is to aid the organizations in Buffalo who are working to bring the GFPP to the city. The report does this by outlining the time and steps involved in the program, identifying opportunities and challenges, identifying lessons learned, and providing recommendations

Synchronously-pumped OPO coherent Ising machine: benchmarking and prospects

The coherent Ising machine (CIM) is a network of optical parametric oscillators (OPOs) that solves for the ground state of Ising problems through OPO bifurcation dynamics. Here, we present experimental results comparing the performance of the CIM to quantum annealers (QAs) on two classes of NP-hard optimization problems: ground state calculation of the Sherrington-Kirkpatrick (SK) model and MAX-CUT. While the two machines perform comparably on sparsely-connected problems such as cubic MAX-CUT, on problems with dense connectivity, the QA shows an exponential performance penalty relative to CIMs. We attribute this to the embedding overhead required to map dense problems onto the sparse hardware architecture of the QA, a problem that can be overcome in photonic architectures such as the CIM

Exceptional surgeries on alternating knots

We give a complete classification of exceptional surgeries on hyperbolic alternating knots in the 3-sphere. As an appendix, we also show that the Montesinos knots M (-1/2, 2/5, 1/(2q + 1)) with q at least 5 have no non-trivial exceptional surgeries. This gives the final step in a complete classification of exceptional surgery on arborescent knots.Comment: 30 pages, 19 figures. v2: recomputation performed via the newest version of hikmot, v3: revised according to referees' comments, to appear in Comm. Anal. Geo

Multiple inflation and the WMAP 'glitches' II. Data analysis and cosmological parameter extraction

Detailed analyses of the WMAP data indicate possible oscillatory features in the primordial curvature perturbation, which moreover appears to be suppressed beyond the present Hubble radius. Such deviations from the usual inflationary expectation of an approximately Harrison-Zeldovich spectrum are expected in the supergravity-based 'multiple inflation' model wherein phase transitions during inflation induce sudden changes in the mass of the inflaton, thus interrupting its slow-roll. In a previous paper we calculated the resulting curvature perturbation and showed how the oscillations arise. Here we perform a Markov Chain Monte Carlo fitting exercise using the 3-year WMAP data to determine how the fitted cosmological parameters vary when such a primordial spectrum is used as an input, rather than the usually assumed power-law spectrum. The 'concordance' LCDM model is still a good fit when there is just a 'step' in the spectrum. However if there is a 'bump' in the spectrum (due e.g. to two phase transitions in rapid succession), the precision CMB data can be well-fitted by a flat Einstein-de Sitter cosmology without dark energy. This however requires the Hubble constant to be h ~ 0.44 which is lower than the locally measured value. To fit the SDSS data on the power spectrum of galaxy clustering requires a ~10% component of hot dark matter, as would naturally be provided by 3 species of neutrinos of mass ~0.5 eV. This CHDM model cannot however fit the position of the baryon acoustic peak in the LRG redshift two-point correlation function. It may be possible to overcome these difficulties in an inhomogeneous Lemaitre-Tolman-Bondi cosmological model with a local void, which can potentially also account for the SN Ia Hubble diagram without invoking cosmic acceleration.Comment: 27 pages, 18 figures (RevTex); Tables revised to include the \chi^2 and "Akaike information criterion" in comparison of cosmological models; Fits to WMAP3 EE spectrum shown; Additional references added; Accepted for publication in in Phys Rev

Space Complexity Analysis of RSA and ECC Based Security Algorithms in Cloud Data

Cloud computing is an important development trend in information technology all over the world. Nowadays, the cloud data security technique exploits the symmetric encryption and asymmetric encryption algorithms within the capability of the stronger authentication techniques. A major risk of data security in cloud computing environment becomes a serious problem by reason of the data which is stored diversely over the cloud. Both the data security and privacy are the two main characteristics of cloud information technologies for user’s concern. We discuss in this paper, a number of existing techniques used to provide security in the field of cloud computing on the basis of different parameters. It will be helpful to improve assure the security of data storage in a cloud environment

Funnels in Energy Landscapes

Local minima and the saddle points separating them in the energy landscape are known to dominate the dynamics of biopolymer folding. Here we introduce a notion of a "folding funnel" that is concisely defined in terms of energy minima and saddle points, while at the same time conforming to a notion of a "folding funnel" as it is discussed in the protein folding literature.Comment: 6 pages, 3 figures, submitted to European Conference on Complex Systems 200

Kinetics of the Wako-Saito-Munoz-Eaton Model of Protein Folding

We consider a simplified model of protein folding, with binary degrees of freedom, whose equilibrium thermodynamics is exactly solvable. Based on this exact solution, the kinetics is studied in the framework of a local equilibrium approach, for which we prove that (i) the free energy decreases with time, (ii) the exact equilibrium is recovered in the infinite time limit, and (iii) the folding rate is an upper bound of the exact one. The kinetics is compared to the exact one for a small peptide and to Monte Carlo simulations for a longer protein, then rates are studied for a real protein and a model structure.Comment: 4 pages, 4 figure