Showing papers by "Guang-Can Guo published in 1998"
TL;DR: In this article, the authors constructed a probabilistic quantum cloning machine by a general unitary reduction operation, which yielded faithful copies of the input states with a postselection of the measurement results.
Abstract: We construct a probabilistic quantum cloning machine by a general unitary-reduction operation. With a postselection of the measurement results, the machine yields faithful copies of the input states. It is shown that the states secretly chosen from a certain set $S\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}{|{\ensuremath{\Psi}}_{1}〉,|{\ensuremath{\Psi}}_{2}〉,\dots{},|{\ensuremath{\Psi}}_{n}〉}$ can be probabilistically cloned if and only if $|{\ensuremath{\Psi}}_{1}〉,|{\ensuremath{\Psi}}_{2}〉,\dots{},\mathrm{and}|{\ensuremath{\Psi}}_{n}〉$ are linearly independent. We derive the best possible cloning efficiencies. Probabilistic cloning has a close connection with the problem of identification of a set of states, which is a type of $n+1$ outcome measurement on $n$ linearly independent states. The optimal efficiencies for this type of measurement are obtained.
377 citations
TL;DR: In this article, the authors make the assumption that all quantum bits (qubits) interact with the same environment rather than the assumption of separate environments for different qubits, and they find that the qubits decohere collectively.
Abstract: Decoherence in quantum-computer memory due to the inevitable coupling to the external environment is examined. We make the assumption that all quantum bits (qubits) interact with the same environment rather than the assumption of separate environments for different qubits. It is found that the qubits decohere collectively. For some kinds of entangled input states, no decoherence occurs at all in the memory, even if the qubits are interacting with the environment. Based on this phenomenon, a scheme is proposed for reducing the collective decoherence. We also discuss possible implications of this decoherence model for quantum measurements.
246 citations
TL;DR: In this paper, it was shown that two non-orthogonal states secretly chosen from a certain set can be faithfull in a probabilistic fashion through a unitary evolution together with a measurement.
95 citations
TL;DR: In this article, the explicit conditions for independent decoherence were derived from a practical quantum register consisting of many qubits, and they were used to derive the conditions for quantum error correction schemes.
Abstract: In quantum error correction schemes, it is usually assumed that the qubits are decohered independently. Starting from a practical decoherence model of the quantum register consisting of many qubits, we derive the explicit conditions for independent decoherence.
10 citations
TL;DR: In this paper, the atom number of a Bose condensate was measured using a quantum non-deflating measurement method, and the number of the atoms in the Bose number was determined.
6 citations
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TL;DR: In this paper, a scheme based on realistic quantum computer models is described for suppressing noise in quantum computation without the cost of stringent quantum computing resources, which can be used to make arbitrarily accurate quantum computation possible.
Abstract: To make arbitrarily accurate quantum computation possible, practical realization of quantum computers will require suppressing noise in quantum memory and gate operations to make it below a threshold value. A scheme based on realistic quantum computer models is described for suppressing noise in quantum computation without the cost of stringent quantum computing resources.
2 citations
TL;DR: In this article, the Bose-Einstein condensate is associated with a one-dimensional nonlinear Schrodinger equation and a soliton solution, and the influence of the initial condition on the solution is discussed.
1 citations