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Comment on "Nonadiabatic Conditional Geometric Phase Shift with NMR"  [PDF]
LiXiang Cen,XinQi Li,YiJing Yan
Physics , 2002,
Abstract: We clarify that the nonadiabatic scheme based on a parallel extension of the adiabatic scenario cannot realize the desired goal of quantum computation.
The nonadiabatic conditional geometric phase shift in a coiled fiber system
螺旋光纤系统中非绝热条件几何相移

SHEN Jian-qi,Zhuang Fei,
沈建其
,庄飞

物理学报 , 2005,
Abstract: The nonadiabatic conditional geometric phase gate is required in the topological quantum computation in order to overcome the conflict between the requirement of adiabatic condition(to avoid the severe distortion from the nonadiabaticity to the results) and the removal of decoherence effects. It was demonstrated that the effective Hamiltonian that describes the propagation of photon fields inside the coiled fiber is just the Wang Matsumoto type of Hamiltonian. Thus, the coiled fiber system will automatically generate the nonadiabatic conditional geometric phase shift. In addition, it was shown that the dynamical phase(resulting from the effective Hamiltonian) acquired by the polarized photons vanishes, and the conditional initial state can be easily prepared only by controlling the initial wave vector of photons. In a word, the coiled fiber system can automatically satisfy the requirements and conditions, which were proposed by Wang and Matsumoto in order to create the nonadiabatic conditional geometric phase shift in their NMR scheme.
Geometric phase shift in quantum computation using superconducting nanocircuits: nonadiabatic effects  [PDF]
Shi-Liang Zhu,Z. D. Wang
Physics , 2002, DOI: 10.1103/PhysRevA.66.042322
Abstract: The nonadiabatic geometric quantum computation may be achieved using coupled low-capacitance Josephson juctions. We show that the nonadiabtic effects as well as the adiabatic condition are very important for these systems. Moreover, we find that it may be hard to detect the adiabatic Berry's phase in this kind of superconducting nanocircuits; but the nonadiabatic phase may be measurable with current techniques. Our results may provide useful information for the implementation of geometric quantum computation.
Conditional AIC under Covariate Shift with Application to Small Area Prediction  [PDF]
Yuki Kawakubo,Shonosuke Sugasawa,Tatsuya Kubokawa
Statistics , 2015,
Abstract: In this paper, we consider the problem of selecting explanatory variables of fixed effects in linear mixed models under covariate shift, which is the situation that the values of covariates in the predictive model are different from those in the observed model. We construct a variable selection criterion based on the conditional Akaike information introduced by Vaida and Blanchard (2005) and the proposed criterion is generalization of the conditional AIC in terms of covariate shift. We especially focus on covariate shift in small area prediction and show usefulness of the proposed criterion through empirical studies.
Non-adiabatic conditional geometric phase shift with NMR  [PDF]
Wang Xiang-Bin,Matsumoto Keiji
Physics , 2001, DOI: 10.1103/PhysRevLett.87.097901
Abstract: Conditional geometric phase shift gate, which is fault tolerate to certain errors due to its geometric property, is made by NMR technique recently under adiabatic condition. By the adiabatic requirement, the result is inexact unless the Hamiltonian changes extremely slowly in the process. However, in quantum computation, everything has to be completed within the decoherence time. High running speed of every gate in quantum computation is demanded because the power of quantum computer can be exponentially proportional to the maximum number of logic gate operation that can be taken sequentially within the decoherence time. Adiabatic condition makes any fast conditional Berry phase(cyclic adiabatic geometric phase) shift gate impossible. Here we show that by using a new designed sequence of simple operations with an additional vertical magnetic field, the conditional geometric phase shift can be done non-adiabatically. Therefore geometric quantum computation can be done in the same speed level of usual quantum computation.
Demonstration of conditional quantum phase shift between ions in a solid  [PDF]
J. J. Longdell,M. J. Sellars,N. B. Manson
Physics , 2004, DOI: 10.1103/PhysRevLett.93.130503
Abstract: Due to their potential for long coherence times, dopant ions have long been considered promising candidates for scalable solid state quantum computing. However, the demonstration of two qubit operation has proven to be problematic, largely due to the difficulty of addressing closely spaced ions. Here we use optically active ions and optical frequency addressing to demonstrate a conditional phase shift between two qubits.
On the nonadiabatic geometric quantum gates  [PDF]
Wang Xiang-Bin,Matsumoto Keiji
Physics , 2001,
Abstract: Motivated for the fault tolerant quantum computation, quantum gate by adiabatic geometric phase shift is extensively investigated. In this paper, we demonstrate the nonadiabatic scheme for the geometric phase shift and conditional geometric phase shift. Essentially, the new scheme is simply to add an appropriate additional field. With this additional field, the state evolution can be controlled exactly on a dynamical phase free path. Geometric quantum gates for single qubit and the controlled NOT gate for two qubits are given.
Nonreciprocal transmission of neutrons through the noncoplanar magnetic system  [PDF]
D. A. Tatarskiy,A. V. Petrenko,S. N. Vdovichev,O. G. Udalov,Yu. V. Nikitenko,A. A. Fraerman
Physics , 2014,
Abstract: We report on observation of the time reversal symmetry breaking in unpolarized neutrons scattering experiment. Neutron transmittivity through the system consisting of two magnetic mirrors placed in an external magnetic field is measured. Time reversal symmetry holds for coplanar magnetic configuration, meaning that transmitted intensity does not change when interchanging neutron source and detector. Contrarily, for noncoplanar magnetic configuration the time reversal symmetry breaks down. In this case the transmitted intensity changes when interchanging the source and detector. The observed time reversal symmetry breaking is the consequence of the one of the most fundamental properties of quantum mechanics, namely the non-commutativity of spin algebra.
Far-off resonance conditional phase-shifter using the ac-Stark shift  [PDF]
N. A. Proite,D. D. Yavuz
Physics , 2009, DOI: 10.1016/j.optcom.2009.05.031
Abstract: We propose a simple technique that achieves a conditional phase shift of pi radians between two weak lasers with energies at the 1000-photon level. The key idea is to set up a V-system with two far-off resonant lasers by coupling the ground state to two excited electronic states. The lasers interact through the ac Stark shift of the ground state and thereby acquire a large conditional phase shift.
Nonadiabatic tapered optical fiber for biosensor applications
Hamid Latifi,Mohammad I. Zibaii,Seyed M. Hosseini,Pedro Jorge
Photonic Sensors , 2012, DOI: 10.1007/s13320-012-0086-z
Abstract: A brief review on biconical tapered fiber sensors for biosensing applications is presented. A variety of configurations and formats of this sensor have been devised for label free biosensing based on measuring small refractive index changes. The biconical nonadiabatic tapered optical fiber offers a number of favorable properties for optical sensing, which have been exploited in several biosensing applications, including cell, protein, and DNA sensors. The types of these sensors present a low-cost fiber biosensor featuring a miniature sensing probe, label-free direct detection, and high sensitivity.
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