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We present a detailed analysis of the impact on quantum modular exponentiation of architectural features and possible concurrent gate execution. Various arithmetic algorithms are evaluated for execution time, potential concurrency, and space trade-offs. We find that to exponentiate an n-bit number, for storage space 100n ͑20 times the minimum 5n͒, we can(More)
We evaluate the performance of quantum arithmetic algorithms run on a distributed quantum computer (a quantum multicomputer). We vary the node capacity and I/O capabilities, and the network topology. The tradeoff of choosing between gates executed remotely, through "teleported gates" on entangled pairs of qubits (telegate), versus exchanging the relevant(More)
The quantum superposition principle states that an entity can exist in two different states simultaneously, counter to our 'classical' intuition. Is it possible to understand a given system's behaviour without such a concept? A test designed by Leggett and Garg can rule out this possibility. The test, originally intended for macroscopic objects, has been(More)
The epitaxial film of the highly enriched 76 Ge isotope (average mass 75.63) was grown on an intrinsic Ge(111) substrate in an ultrahigh vacuum system (base pressure 10 Ϫ11 mbar) by molecular beam epi-taxy at a substrate temperature of 720 K, well below the threshold for bulk interdiffusion [H. D. Fuchs et al., Phys. Rev. B 51, 16817 (1995)]. Before and(More)
We evaluate the performance of quantum arithmetic algorithms run on a distributed quantum computer (a quantum multicomputer). We vary the node capacity and I/O capabilities, and the network topology. The tradeoff of choosing between gates executed remotely, through “teleported gates” on entangled pairs of qubits (telegate), versus exchanging the(More)
Quantum computation requires qubits that can be coupled in a scalable manner, together with universal and high-fidelity one- and two-qubit logic gates. Many physical realizations of qubits exist, including single photons, trapped ions, superconducting circuits, single defects or atoms in diamond and silicon, and semiconductor quantum dots, with single-qubit(More)
We show how the execution time of algorithms on quantum computers depends on the architecture of the quantum computer, the choice of algorithms (including subroutines such as arithmetic), and the " clock speed " of the quantum computer. The primary architectural features of interest are the ability to execute multiple gates concurrently, the number of(More)
Entanglement is the quintessential quantum phenomenon. It is a necessary ingredient in most emerging quantum technologies, including quantum repeaters, quantum information processing and the strongest forms of quantum cryptography. Spin ensembles, such as those used in liquid-state nuclear magnetic resonance, have been important for the development of(More)
Using ultraviolet-laser assisted local-electrode atom-probe ͑UV-LEAP͒ tomography, we obtain three-dimensional ͑3D͒ atom-by-atom images of isotopically modulated 28 Si and 30 Si ultrathin layers having thicknesses in the range of 5–30 nm. The 3D images display interfaces between the different monoisotopic layers with an interfacial width of ϳ1.7 nm, thus(More)
Large-scale quantum computers must be built upon quantum bits that are both highly coherent and locally controllable. We demonstrate the quantum control of the electron and the nuclear spin of a single (31)P atom in silicon, using a continuous microwave magnetic field together with nanoscale electrostatic gates. The qubits are tuned into resonance with the(More)