P. L. Knight

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We describe how a quantum system composed of a cavity eld interacting with a movable mirror can be utilized to generate a large variety of nonclassical states of both the cavity eld and the mirror. First we consider state preparation of the cavity eld. The system dynamics will prepare a single mode of the cavity eld in a multicomponent Schrodinger cat(More)
We introduce the quantum quincunx, which physically demonstrates the quantum walk and is analogous to Galton’s quincunx for demonstrating the random walk. In contradistinction to the theoretical studies of quantum walks over orthogonal lattice states, we introduce quantum walks over nonorthogonal lattice states (specifically, coherent states on a circle) to(More)
The last few years have seen impressive progress in the experimental demonstration of quantum information processing [1]. Among the growing number of possible physical scenarios for these demonstrations, the system of laser-cooled trapped ions still remains one of the most experimentally attractive [2–5] (for reviews of iontrap quantum computing, see e.g.(More)
We study numerically the generation of high-order harmonics by two-center molecules for arbitrary angles between the molecular axis and the laser polarization axis. For fixed angle, the harmonic spectrum exhibits a minimum at a frequency which is independent of the laser parameters. The amplitude of each harmonic is strongly angle dependent, and a(More)
We investigate the problem of factorization of large numbers on a quantum computer which we imagine to be realized within a linear ion trap. We derive upper bounds on the size of the numbers that can be factorized on such a quantum computer. These upper bounds are independent of the power of the applied laser. We investigate two possible ways to implement(More)
We argue from the point of view of statistical inference that the quantum relative entropy is a good measure for distinguishing between two quantum states ~or two classes of quantum states! described by density matrices. We extend this notion to describe the amount of entanglement between two quantum systems from a statistical point of view. Our measure is(More)
In this paper we show how the fault–tolerant error correction scheme recently proposed by DiVincenzo and Shor may be improved. Our scheme, unlike the earlier one, can also deal with a single error that might occur during the gate operations that are required for the implementation of the error correction and not only in–between the gates and hence presents(More)
A thermal field, which frequently appears in problems of decoherence, provides us with minimal information about the field. We study the interaction of the thermal field and a quantum system composed of two qubits and find that such a chaotic field with minimal information can nevertheless entangle the qubits which are prepared initially in a separable(More)