Ambiguity int he contact between laboratory instruments and equations of quantum mechanics is formulated in terms of responses of the instruments to commands transmitted to them by a Classical digital Process-control Computer (CPC); in this way instruments are distinguished from quantum- mechanical models (sets of equations) that specify what is desired of the instruments. Results include: (1) a formulation of quantum mechanics adapted to computer- controlled instruments; (2) a lower bound on the precision of unitary transforms required for quantum searching and a lower bound on sample size needed to show that instruments implement a desired model at that precision; (3) a lower bound on precision of timing required of a CPC in directing instruments; (4) a demonstration that guesswork is necessary in ratcheting up the precision of commands.
Neural Networks and Neurocomputing provide a natural paradigm for parallel and distributed processing. Neurocomputing within the context of classical computation have been used for approximation and classification tasks with some success. In this paper we propose a model for Quantum Neurocomputation and explore some of its properties and potential applications to pattern recognition.
Recent progress in nano-meter structure and measurements is going to provide us the freedom to domesticate fast correlations between atoms in an ensemble, manifesting them at macroscopic level. Here, we show a possibility to generate an electron coherence within an atomic ensemble, via the quantum resonance due to parity inheriting dynamic dipole-dipole interaction. We built up a realistic Hamiltonian having a combinatorial probability factors for the dynamic dipole-dipole quantum resonance. This leads to the precise simulation of the process that will actually occur in nature obeying the energy conservation law. We also show a preliminary experimental data suggestive of the dynamic dipole-dipole mode. These results lead to our proposal of solid state room temperature quantum computer, e.g. by a solid state qubit system of arrayed quantum dots designed to resist against phase errors as well as bit errors.
In order to image recognition using a register-type quantum computer consisting of electronic spins, this paper presents a unitary transformation for quantum state image representation of input image, and another unitary transformation for matching (or similarity computation) between input image and reference image data. Moreover, it shows some improved image recognition algorithms by quantum computer, based on Gram-Schmidt's orthogonalization.
We review results of a recently developed model of a microscopic quantum system interacting with the macroscopic world components which are modeled by collections of bosonic modes. The interaction is via a general operator (Lambda) of the system, coupled to the creation and annihilation operators of the environment modes. We assume that in the process of a nearly instantaneous quantum measurement, the function of the environment involves two distinct parts: the pointer and the bath. Interaction of the system with the bath leads to decoherence such that the system and the pointer both evolve into a statistical mixture state described by the density matrix such that the system is in one of the eigenstates of (Lambda) with the correct quantum mechanical probability, whereas the expectation values of pointer operators retain amplified information on that eigenstate. We argue that this process represents the initial step of a quantum measurement.
We evaluate how quantum computing can be applied to security problems for software agents. Agent-based computing, which merges technological advances in artificial intelligence and mobile computing, is a rapidly growing domain, especially in applications such as electronic commerce, network management, information retrieval, and mission planning. System security is one of the more eminent research areas in agent-based computing, and the specific problem of protecting a mobile agent from a potentially hostile host is one of the most difficult of these challenges. In this work, we describe our agent model, and discuss the capabilities and limitations of classical solutions to the malicious host problem. Quantum computing may be extremely helpful in addressing the limitations of classical solutions to this problem. This paper highlights some of the areas where quantum computing could be applied to agent security.
We present a brief review of the current state of the art of quantum computation with trapped ions, with particular emphasis on the problems caused by `heating' of the ions' motional degrees of freedom.
The inclusive rate is considered as a disturbance measure in key distribution in quantum cryptography. Bennett's two- state protocol is addressed for the case in which a positive operator valued measure is implemented by the legitimate receiver in the presence of individual attack by a general unitary disturbing eavesdropping probe. The maximum Renyi information gain by the disturbing probe is calculated for given receiver error and inconclusive rates. It is demonstrated explicitly that less information is available to an eavesdropper at fixed inconclusive rate and error rate than is available at fixed error rate only.
Recently we proved that there are two non-isomorphic models of the calculus of quantum logic corresponding to an infinite-dimensional Hilbert space representation: an orthomodular lattice and a weakly orthomodular lattice. We also discovered that there are two non-isomorphic models of the calculus of classical logic: a distributive lattice (Boolean algebra) and a weakly distributive lattice. In this work we consider implications of these results to a quantum simulator which should mimic quantum systems by giving precise instructions on how to produce input state, how to evolve them, and how to read off the final states. We analyze which conditions quantum states of a quantum computer currently obey and which they should obey in order to enable full quantum computing, i.e., proper quantum mathematics. In particular we find several new conditions which lattices of Hilbert space subspaces must satisfy.
A quantum device simulating the human decision making process is introduced. It consists of quantum recurrent nets generating stochastic processes which represent the motor dynamics, and of classical neural nets describing the evolution of probabilities of these processes which represent the mental dynamics. The autonomy of the decision making process is achieved by a feedback from the mental to motor dynamics which changes the stochastic matrix based upon the probability distribution. This feedback replaces unavailable external information by an internal knowledge- base stored in the mental model in the form of probability distributions. As a result, the coupled motor-mental dynamics is described by a nonlinear version of Markov chains which can decrease entropy without an external source of information. Applications to common sense based decisions as well as to evolutionary games are discussed. An example exhibiting self-organization is computed using quantum computer simulation. Force on force and mutual aircraft engagements using the quantum decision maker dynamics are considered.
We are currently working on Semiconductor Cylinder Fibers (SCF), fibers with a thin semiconductor layer at the glass core glass cladding boundary. We hope that these fibers can eventually be used as both S aturable Absorbers (SA) and Fiber Light Amplifiers (FLA). We use a rod and tube method for fabricating these fibers. The three fabrication process steps, semiconductor deposition, collapse, and fiber drawing have been working well since the summer of 1 999. We have mathematical models for the fabrication process steps that allows us to calculate the required temperatures and pressures used. The fabrication process is very reproducible.
We extend definitions of the linear response functions of many-body theory to a system of Bose condensed atoms interacting with laser light. We use resulting corrections to the ground state energy of the system to investigate the possibility of detecting mesoscopic Schrodinger cat states.
The realization of a five-qubit nuclear-magnetic-resonance quantum computer is reported, from the design and synthesis of a suitable molecule through the implementation of pulse sequences on a multi-channel spectrometer. The quantum computer is shown to distinguish between balanced and constant functions on four bits, making use of quantum parallelism.