Superadiabatic STIRAP: population transfer and quantum rotation gates

Stimulated Raman Adiabatic Passage is an important pro- cess for population transfer as well as for implementing quantum gates. This process requires large Rabi frequencies, which is an undesirable in many experimental applications. To overcome this problem transition- less (superadiabatic) STIRAP was proposed. In this paper we study the role of superadiabatic STIRAP in two examples, population transfer and quantum rotation gates. The effect of dephasing was also investigated by computing the fidelity. We have shown that the damping of the excited state has a little effect but the dephasing of the ground state leads to imperfect population transfer and imperfect rotation gates

Rotation gates with controlled adiabatic evolutions in open systems

Single quantum rotation gates can be perfectly implemented in a closed system using the controlled adiabatic evolutions process proposed by Itay Hen that may lead to build some quantum circuit blocks [Phys. Rev. A, 022309 (2015)]. These adiabatic evolutions yield to vanishing geometric phases. In this work, we extended Itay’s work by considering a more realistic model where the qubits are subjected to decoherence effects during the adiabatic evolution process. We demonstrate that, in the case of an open system, the decoherence leads to nonvanishing geometric phases and drastically reduces the performance of the quantum rotation gates bellow the fidelity target (0.999)

Single-qubit Rotation Gate Using Three-level Lambda Systems

Abstract: In this paper we investigate the effect of time separation and delay between two f-STIRAP on single-qubit rotation gate based on Lacour et al (2006 Opt. Commun. 264 362). The f-STIRAP is a basic method used to adiabatically transfer population between lower states, where the two pulses terminate simultaneously while maintaining a constant ratio of amplitudes. Furthermore, we obtain numerically the optimal values for the time separation and delay for a perfect single-qubit rotation gate

Atomic coupler with two-mode squeezed vacuum state

We investigate the entanglement transfer from the two-mode squeezed state (TMS) to the atomic system by studying the dependence of the negativity on the coupling between the modes of the waveguides. This study is very important since the entanglement is an important feature which has no classical counterpart and it is the main resource of quantum information processing. We use a linear coupler which is composed of two waveguides placed close enough to allow exchanging energy between them via evanescent waves. Each waveguide includes a localized atom

The computational power of Watson-Crick grammars: Revisited

A Watson-Crick finite automaton is one of DNA computational models using the Watson-Crick complementarity feature of deoxyribonucleic acid (DNA). We are interested in investigating a grammar counterpart of Watson-Crick automata. In this paper, we present results concerning the generative power of Watson-Crick (regular, linear, context-free) grammars. We show that the family of Watson-Crick context-free languages is included in the family of matrix languages

Quantum rotation gates with controlled nonadiabatic evolutions

Quantum gates can be implemented adiabatically and nonadiabatically. Many schemes used at least two sequentially implemented gates to obtain an arbitrary one-qubit gate. Recently, it has been shown that nonadiabatic gates can be realized by single-shot implementation. It has also been shown that quantum gates can be implemented with controlled adiabatic evolutions. In this paper, we combine the advantage of single-shot implementation with controlled adiabatic evolutions to obtain controlled nonadiabatic evolutions. We also investigate the robustness to different types of errors. We find that the fidelity is close to unity for realistic decoherence rate

Watson–Crick context-free grammars: Grammar simplifications and a parsing algorithm

A Watson–Crick (WK) context-free grammar, a context-free grammar with productions whose right-hand sides contain nonterminals and double-stranded terminal strings, generates complete double-stranded strings under Watson–Crick complementarity. In this paper, we investigate the simplification processes of Watson–Crick context-free grammars, which lead to defining Chomsky like normal form for Watson–Crick context-free grammars. The main result of the paper is a modified CYK (Cocke–Younger–Kasami) algorithm for Watson–Crick context-free grammars in WK-Chomsky normal form, allowing to parse double-stranded strings in O(n^6) time

Enhancing photon generation in cavity through antiresonant terms of the vacuum Rabi coupling

The Rabi model describes the simplest interaction between a two-level system and a bosonic mode beyond the rotating wave approximation. The antiresonant terms that result from this coherent interaction play an important role. In this paper, we go beyond the rotating wave approximation even for the interaction with vacuum. This leads to the 'incoherent' antiresonant terms. Using the master equation which includes both coherent and incoherent antiresonant terms, we numerically compute the mean photon number and show that these incoherent antiresonant terms enhance the generation of mean photon number. Moreover we study numerically the effect of the detuning and show that it also enhances the generation of photons. Finally, we generalize our result to two two-level and two-mode systems

Quantum properties of the three-mode squeezed operator: triply concurrent parametric amplifiers

In this paper, we study the quantum properties of the three-mode squeezed operator. This operator is constructed from the optical parametric oscillator based on the three concurrent $\chi^{(2)}$ nonlinearities. We give a complete treatment for this operator including the symmetric and asymmetric nonlinearities cases. The action of the operator on the number and coherent states are studied in the framework of squeezing, second-order correlation function, Cauchy-Schwartz inequality and single-mode quasiprobability function. The nonclassical effects are remarkable in all these quantities. We show that the nonclassical effects generated by the asymmetric case--for certain values of the system parameters--are greater than those of the symmetric one. This reflects the important role for the asymmetry in the system. Moreover, the system can generate different types of the Schr\"odinger-cat states.Comment: 21 pages, 14 figures; comments are most welcom

Introduction to mathematical statistics

This is the course taught to second year students during the semester 1 2016/2017 at Department of Computer Science, Kulliyyah of Information and Communication Technology, International Islamic University Malaysia. This is the last semester this course is offered. This course is an introductory to mathematical statistics. It is based on the textbook: Introduction to Mathematical Statistics and Its Applications by Richard J. Larsen and Morris L. Marx. We focus on random variables, estimation, and hypothesis testing. We also show how to simulate some of the probability density functions using R language which is an open source and can be downloaded for free