A central problem in quantum computation is to understand which quantum circuits are useful for exponential speed-ups over classical computation. We address this question in the setting of query complexity and show that for almost any sufficiently long quantum circuit one can construct a black-box problem which is solved by the circuit with a constant number of quantum queries, but which requir...

Alexandre Blais, Jay Gambetta, A. Wallraff, D. I. Schuster, S. M. Girvin, M. H. Devoret, and R. J. Schoelkopf Departments of Applied Physics and Physics, Yale University, New Haven, Connecticut 06520, USA Département de Physique et Regroupement Québécois sur les Matériaux de Pointe, Université de Sherbrooke, Sherbrooke, Québec, Canada J1K 2R1 Department of Physics, ETH Zurich, CH-8093 Zürich, S...

   In this paper we propose a simulation study to carry out dynamic analysis of CNTFET-based digital circuit, introducing in the semi-empirical compact model for CNTFETs, already proposed by us, both the quantum capacitance effects and the sub-threshold currents. To verify the validity of the obtained results, a comparison with Wong model was carried out. Our mode...

We present an efficient family of quantum circuits for a fundamental primitive in quantum information theory, the Schur transform. The Schur transform on n d dimensional quantum systems is a transform between a standard computational basis to a labelling related to the representation theory of the symmetric and unitary groups. If we desire to implement the Schur transform to an accuracy of ǫ, t...

Electromagnetic waves are ideal candidates for transmitting information in a quantum network as they can be routed rapidly and efficiently between locations using optical fibres or microwave cables. Yet linking quantum-enabled devices with cables has proved difficult because most cavity or circuit quantum electrodynamics systems used in quantum information processing can only absorb and emit si...

We review the first experiment on dynamic transport in a phase-coherent quantum conductor. In our discussion, we highlight the use of time-dependent transport as a means of gaining insight into charge relaxation on a mesoscopic scale. For this purpose, we studied the ac conductance of a model quantum conductor, i.e. the quantum RC circuit. Prior to our experimental work, Büttiker et al (1993 Ph...

G. Haack,1 F. Helmer,2 M. Mariantoni,3 F. Marquardt,4 and E. Solano5,6 1Département de Physique Théorique, Université de Genève, CH-1211 Genève 4, Switzerland 2Department of Physics, ASC and CeNS, Ludwig-Maximilians-Universität, Theresienstrasse 37, 80333 München, Germany 3Department of Physics, University of California, Santa Barbara, California 93106, USA 4Institut für Theoretische Physik, Un...

A type II GaSb quantum ring solar cell is fabricated and measured under the concentrated sunlight. The external quantum efficiency confirms the extended absorption from the quantum rings at long wavelength coinciding with the photoluminescence results. The short-circuit current of the quantum ring devices is 5.1% to 9.9% more than the GaAs reference's under various concentrations. While the qua...

Quantum-circuit optimization is essential for any practical realization of quantum computation, in order to beat decoherence. We present a scheme for implementing the final stage in the compilation of quantum circuits, i.e. for finding the actual physical realizations of the individual modules in the quantum-gate library. We find that numerical optimization can be efficiently utilized in order ...