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Perfect state transfer in quantum spin networks.
It is shown that 2log3N is the maximal perfect communication distance for hypercube geometries if one allows fixed but different couplings between the qubits, then perfect state transfer can be achieved over arbitrarily long distances in a linear chain.
Quantum Computation and Shor's Factoring Algorithm
The authors give an exposition of Shor's algorithm together with an introduction to quantum computation and complexity theory, and discuss experiments that may contribute to its practical implementation.
Quantum computers and dissipation
We analyse dissipation in quantum computation and its destructive impact on the efficiency of quantum algorithms. Using a general model of decoherence, we study the time evolution of a quantum
Perfect Transfer of Arbitrary States in Quantum Spin Networks
We propose a class of qubit networks that admit perfect state transfer of any two-dimensional quantum state in a fixed period of time. We further show that such networks can distribute arbitrary
Improvement of frequency standards with quantum entanglement
The optimal precision of frequency measurements in the presence of decoherence is discussed. We analyze different preparations of n two-level systems as well as different measurement procedures. We
Universality in quantum computation
We show that in quantum computation almost every gate that operates on two or more bits is a universal gate. We discuss various physical considerations bearing on the proper definition of
Machines, logic and quantum physics
Galileo's introduction of mathematically formulated, testable theories into physics marked the transition from the Aristotelian conception of physics to its modern status as a theoretical, conjectural and empirical science.
Geometric quantum computation using nuclear magnetic resonance
A nuclear magnetic resonance experiment is performed in which a conditional Berry phase is implemented, demonstrating a controlled phase shift gate, and suggests the possibility of an intrinsically fault-tolerant way of performing quantum gate operations.
Entanglement-based secure quantum cryptography over 1,120 kilometres
Entanglement-based QKD is demonstrated between two ground stations separated by 1,120 kilometres at a finite secret-key rate of 0.12 bits per second, without the need for trusted relays, which increases the secure distance on the ground tenfold but also increases the practical security of QKKD to an unprecedented level.