802,309 research outputs found
Morphological Computation: Nothing but Physical Computation
The purpose of this paper is to argue against the claim that morphological computation is substantially different from other kinds of physical computation. I show that some (but not all) purported cases of morphological computation do not count as specifically computational, and that those that do are solely physical computational systems. These latter cases are not, however, specific enough: all computational systems, not only morphological ones, may (and sometimes should) be studied in various ways, including their energy efficiency, cost, reliability, and durability. Second, I critically analyze the notion of âoffloadingâ computation to the morphology of an agent or robot, by showing that, literally, computation is sometimes not offloaded but simply avoided. Third, I point out that while the morphology of any agent is indicative of the environment that it is adapted to, or informative about that environment, it does not follow that every agent has access to its morphology as the model of its environment
Quantum computation and the physical computation level of biological information processing
On the basis of introspective analysis, we establish a crucial requirement
for the physical computation basis of consciousness: it should allow processing
a significant amount of information together at the same time. Classical
computation does not satisfy the requirement. At the fundamental physical
level, it is a network of two body interactions, each the input-output
transformation of a universal Boolean gate. Thus, it cannot process together at
the same time more than the three bit input of this gate - many such gates in
parallel do not count since the information is not processed together. Quantum
computation satisfies the requirement. At the light of our recent explanation
of the speed up, quantum measurement of the solution of the problem is
analogous to a many body interaction between the parts of a perfect classical
machine, whose mechanical constraints represent the problem to be solved. The
many body interaction satisfies all the constraints together at the same time,
producing the solution in one shot. This shades light on the physical
computation level of the theories that place consciousness in quantum
measurement and explains how informations coming from disparate sensorial
channels come together in the unity of subjective experience. The fact that the
fundamental mechanism of consciousness is the same of the quantum speed up,
gives quantum consciousness a potentially enormous evolutionary advantage.Comment: 13 page
Physical-resource demands for scalable quantum computation
The primary resource for quantum computation is Hilbert-space dimension.
Whereas Hilbert space itself is an abstract construction, the number of
dimensions available to a system is a physical quantity that requires physical
resources. Avoiding a demand for an exponential amount of these resources
places a fundamental constraint on the systems that are suitable for scalable
quantum computation. To be scalable, the number of degrees of freedom in the
computer must grow nearly linearly with the number of qubits in an equivalent
qubit-based quantum computer.Comment: This paper will be published in the proceedings of the SPIE
Conference on Fluctuations and Noise in Photonics and Quantum Optics, Santa
Fe, New Mexico, June 1--4, 200
Machines, Logic and Quantum Physics
Though the truths of logic and pure mathematics are objective and independent
of any contingent facts or laws of nature, our knowledge of these truths
depends entirely on our knowledge of the laws of physics. Recent progress in
the quantum theory of computation has provided practical instances of this, and
forces us to abandon the classical view that computation, and hence
mathematical proof, are purely logical notions independent of that of
computation as a physical process. Henceforward, a proof must be regarded not
as an abstract object or process but as a physical process, a species of
computation, whose scope and reliability depend on our knowledge of the physics
of the computer concerned.Comment: 19 pages, 8 figure
Computation in Physical Systems: A Normative Mapping Account
The relationship between abstract formal procedures and the activities of actual physical systems has proved to be surprisingly subtle and controversial, and there are a number of competing accounts of when a physical system can be properly said to implement a mathematical formalism and hence perform a computation. I defend an account wherein computational descriptions of physical systems are high-level normative interpretations motivated by our pragmatic concerns. Furthermore, the criteria of utility and success vary according to our diverse purposes and pragmatic goals. Hence there is no independent or uniform fact to the matter, and I advance the âanti-realistâ conclusion that computational descriptions of physical systems are not founded upon deep ontological distinctions, but rather upon interest-relative human conventions. Hence physical computation is a âconventionalâ rather than a ânaturalâ kind
Noise in One-Dimensional Measurement-Based Quantum Computing
Measurement-Based Quantum Computing (MBQC) is an alternative to the quantum
circuit model, whereby the computation proceeds via measurements on an
entangled resource state. Noise processes are a major experimental challenge to
the construction of a quantum computer. Here, we investigate how noise
processes affecting physical states affect the performed computation by
considering MBQC on a one-dimensional cluster state. This allows us to break
down the computation in a sequence of building blocks and map physical errors
to logical errors. Next, we extend the Matrix Product State construction to
mixed states (which is known as Matrix Product Operators) and once again map
the effect of physical noise to logical noise acting within the correlation
space. This approach allows us to consider more general errors than the
conventional Pauli errors, and could be used in order to simulate noisy quantum
computation.Comment: 16 page
- âŠ