A digital control system for high level acoustic noise generation

As part of the modernization of the Acoustic Test Facility at Lockheed Missiles and Space Company, Sunnyvale, a digital acoustic control system was designed and built. The requirements imposed by Lockheed on the control system and the degree to which those requirements were met are discussed. Acceptance test results as well as some of the features of the digital control system not found in traditional manual control systems are discussed

Intra-organizational integration and innovation: organizational structure, environmental contingency and R&D performance

It is widely thought that intra-firm integration has a positive effect on organizational performance, especially in environments characterized by complex and uncertain information. However, counter arguments suggest that integration may limit flexibility and thereby reduce performance in the face of uncertainty. Research and development activities of a firm are especially likely to face complex and uncertain information environments. Following prior work in contingency theory, this paper analyzes the effects of intra-organizational integration on manufacturing firms’ innovative performance. Based on a survey of R&D units in US manufacturing firms and patent data from the NBER patent database, we examine the relation between mechanisms for linking R&D to other units of the firm and the relative innovativeness of the firm. Furthermore, we argue that the impact of integration may vary by the importance of secrecy in protecting firms’ innovation advantages. We find that intra-firm integration is associated with higher self-reported innovativeness and more patents. We also find some evidence that this effect is moderated by the appropriability regime the firm faces, with the benefits of cross-functional integration being weaker in industries where secrecy is especially important. These results both support and develop the contingency model of organizational performance.Innovation; Organizations; Contingency theory;

Quantum Algorithms for Fermionic Quantum Field Theories

Extending previous work on scalar field theories, we develop a quantum algorithm to compute relativistic scattering amplitudes in fermionic field theories, exemplified by the massive Gross-Neveu model, a theory in two spacetime dimensions with quartic interactions. The algorithm introduces new techniques to meet the additional challenges posed by the characteristics of fermionic fields, and its run time is polynomial in the desired precision and the energy. Thus, it constitutes further progress towards an efficient quantum algorithm for simulating the Standard Model of particle physics.Comment: 29 page

Quantum Algorithms for Quantum Field Theories

Quantum field theory reconciles quantum mechanics and special relativity, and plays a central role in many areas of physics. We develop a quantum algorithm to compute relativistic scattering probabilities in a massive quantum field theory with quartic self-interactions (phi-fourth theory) in spacetime of four and fewer dimensions. Its run time is polynomial in the number of particles, their energy, and the desired precision, and applies at both weak and strong coupling. In the strong-coupling and high-precision regimes, our quantum algorithm achieves exponential speedup over the fastest known classical algorithm.Comment: v2: appendix added (15 pages + 25-page appendix

Quantum Computation of Scattering in Scalar Quantum Field Theories

Quantum field theory provides the framework for the most fundamental physical theories to be confirmed experimentally, and has enabled predictions of unprecedented precision. However, calculations of physical observables often require great computational complexity and can generally be performed only when the interaction strength is weak. A full understanding of the foundations and rich consequences of quantum field theory remains an outstanding challenge. We develop a quantum algorithm to compute relativistic scattering amplitudes in massive phi-fourth theory in spacetime of four and fewer dimensions. The algorithm runs in a time that is polynomial in the number of particles, their energy, and the desired precision, and applies at both weak and strong coupling. Thus, it offers exponential speedup over existing classical methods at high precision or strong coupling

BQP-completeness of Scattering in Scalar Quantum Field Theory

Recent work has shown that quantum computers can compute scattering probabilities in massive quantum field theories, with a run time that is polynomial in the number of particles, their energy, and the desired precision. Here we study a closely related quantum field-theoretical problem: estimating the vacuum-to-vacuum transition amplitude, in the presence of spacetime-dependent classical sources, for a massive scalar field theory in (1+1) dimensions. We show that this problem is BQP-hard; in other words, its solution enables one to solve any problem that is solvable in polynomial time by a quantum computer. Hence, the vacuum-to-vacuum amplitude cannot be accurately estimated by any efficient classical algorithm, even if the field theory is very weakly coupled, unless BQP=BPP. Furthermore, the corresponding decision problem can be solved by a quantum computer in a time scaling polynomially with the number of bits needed to specify the classical source fields, and this problem is therefore BQP-complete. Our construction can be regarded as an idealized architecture for a universal quantum computer in a laboratory system described by massive phi^4 theory coupled to classical spacetime-dependent sources.Comment: 41 pages, 7 figures. Corrected typo in foote