Transversality is a simple and effective method for implementing quantum computation faulttolerantly. However, no quantum error-correcting code (QECC) can transversally implement a quantum universal gate set (Eastin and Knill, Phys. Rev. Lett., 102, 110502). Since reversible classical computation is often a dominating part of useful quantum computation, whether or not it can be implemented tran...

The concept of a quantum computer was invented in the beginning of the 1980s as a quantum generalization of the reversible classical computer. After discoveries in the middle of the 1990s of quantum algorithms, which would solve some problems considered intractable for classical computers, the field of quantum computing has developed rapidly. A wide range of quantum systems are investigated for...

We propose an on-demand single-photon source for quantum cryptography using a metal–insulator–semiconductor quantum dot capacitor structure. The main component in the semiconductor is a p-doped quantum well, and the cylindrical gate under consideration is only nanometres in diameter. As in conventional metal–insulator–semiconductor capacitors, our system can also be biased into the inversion re...

Creation of large-scale W state quantum networks is a key step for realization of various quantum information tasks. Regarding the photonics technology, a simple optical setup was proposed for the fusion of two W states. Recently it was shown that via a single Fredkin gate, this basic so-called fusion setup can be enhanced. However the main problem was that the probability of success of realiza...

In this paper, we study the quantum computation realized by an interaction-free measurement (IFM). Using Kwiat et al.’s interferometer, we construct a two-qubit quantum gate that changes one particle’s trajectory according to whether or not the other particle exists in the interferometer. We propose a method for distinguishing Bell-basis vectors, each of which consists of a pair of an electron ...

We present a detailed error analysis of a Rydberg blockade mediated controlled-NOT quantum gate between two neutral atoms as demonstrated recently in Isenhower et al. [Phys. Rev. Lett. 104, 010503 (2010)] and Zhang et al. [ Phys. Rev. A 82, 030306 (2010)]. Numerical solutions of a master equation for the gate dynamics, including all known sources of technical error, are shown to be in good agre...

Quantum logic gates must perform properly when operating on their standard input basis states, as well as when operating on complex superpositions of these states. Experiments using superconducting qubits have validated the truth table for particular implementations of e.g. the controlled-NOT gate 1,2 , but have not fully characterized gate operation for arbitrary superpositions of input states...

The dynamics of a generic quantum XOR gate operation involving two interacting qubits being coupled to a bath of quantum harmonic oscillators is explored. By use of the formally exact quasiadiabatic-propagator path-integral methodology we study the time-resolved evolution of this interacting and decohering two-qubit system in presence of time-dependent external fields. The quality of the XOR ga...

Most aggressively scaled metal-oxide-semiconductor field-effect (MOSFET) transistors have characteristics dimensions entering now in the nanometer scale [1]. In this context, multi-gate nanowire MOSFET’s are considered as the most promising candidates for ultimate CMOS integration, because of their efficient electrostatic coupling between the surrounding gate electrode and the conduction channe...

Implementing precise operations on quantum systems is one of the biggest challenges for building quantum devices in a noisy environment. Dynamical decoupling attenuates the destructive effect of the environmental noise, but so far, it has been used primarily in the context of quantum memories. Here, we experimentally demonstrate a general scheme for combining dynamical decoupling with quantum l...