Quantum computers achieve a speed-up by placing quantum bits (qubits) in superpositions of different states. However, it has recently been appreciated that quantum mechanics also allows one to 'superimpose different operations'. Furthermore, it has been shown that using a qubit to coherently control the gate order allows one to accomplish a task--determining if two gates commute or anti-commute...

Given a gate set S universal for quantum computing, the problem of decomposing a unitary operator U into a circuit over S is known as the synthesis problem. This problem can be solved exactly, if U belongs to the set of circuits generated by S. Otherwise, it can be solved approximately, by finding a circuit U ′ such that ||U ′ −U || < for some chosen precision > 0. The synthesis problem is impo...

A planar double gate quantum wire transistor (QWT) is proposed and demonstrated. The transistor uses a narrow wire gate placed inside the gap of a split gate to create a single one-dimensional ( 1D) quantum wire (QW) . We demonstrate theoretically and experimentally that the wire gate can create a QW potential with a better confinement and therefore larger subband separations than that in other...

In this contribution I survey some topics of current interest in the properties of quantum gates and their assembly into interesting quantum circuits. It may be noted that this paper, like a large fraction of the others to be found in this volume of contributions to the ITP conference on Quantum Coherence and Decoherence, is about quantum computation and, apparently, not about quantum coherence...

abstract: this paper is the first study on the impact of ambient temperature on the electrical characteristics and high frequency performances of double gate armchair graphene nanoribbon field effect transistor (gnrfet). the results illustrate that the gnrfet under high temperature (ht-gnrfet) has the highest cut-off frequency, lowest sub-threshold swing, lowest intrinsic delay and power delay ...

A conditional geometric phase shift gate, which is fault tolerant to certain types of errors due to its geometric nature, was realized recently via nuclear magnetic resonance(NMR) under adiabatic conditions. By the adiabatic requirement, the result is inexact unless the Hamiltonian changes extremely slowly. However, in quantum computation, everything must be completed within the decoherence tim...

A conditional geometric phase shift gate, which is fault tolerant to certain types of errors due to its geometric nature, was realized recently via nuclear magnetic resonance(NMR) under adiabatic conditions. By the adiabatic requirement, the result is inexact unless the Hamiltonian changes extremely slowly. However, in quantum computation, everything must be completed within the decoherence tim...