共查询到20条相似文献,搜索用时 15 毫秒
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We study the possibility of implementing a two-qubit controlled-NOT gate operation in a structure consisting of two semiconductor double quantum dots placed in a high-Q optical microcavity and governed by a resonant laser field. The effect of relaxation processes on the dynamics of the two-electron system is discussed. The dissipation rates allowing quantum error correction algorithms to be used are determined. The existing additional excitation channel (laser pulse) is shown to weaken the effect of the nonideality of the cavity on the evolution of the states. Optimal electron coupling coefficients in the quantum dots with control fields are fitted, in which the controlled qubit is switched with the highest probability and the gate implementation takes several hundreds of picoseconds. 相似文献
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在双模腔QED系统中用原子-腔共振相互作用实现三量子比特Toffoli门 总被引:1,自引:1,他引:0
提出了一种在腔QED系统中用一个五能级原子通过原子-腔共振相互作用实现三量子比特Toffoli 门的方案。在提出的方案当中,两个量子化的腔模充当控制比特,而原子的两个低能态构成目标比特。数值结果表明,当同时考虑原子高能态的自发辐射和腔模的衰减对量子门的保真度的影响时,腔场的衰减是主要的噪声来源。讨论了原子-光场耦合常数的偏差对三量子比特Toffoli 门保真度的影响以及方案在实验上的可行性。 相似文献
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Ludwik Kranz Edyta N. Osika Serajum Monir Yu-Ling Hsueh Lukas Fricke Samuel J. Hile Yousun Chung Joris G. Keizer Rajib Rahman Michelle Y. Simmons 《Advanced functional materials》2024,34(8):2307285
Precision-placed atom qubits in silicon offer a unique means to confine electrons and control their spins with extreme accuracy, which can be leveraged to construct powerful quantum computers. To date atom qubits in silicon have been successfully realized using electrons hosted either on a single phosphorus atom or on a multi-donor quantum dot. Here, a novel molecular regime is explored in which electrons are bound to two donor dots separated by ≈8 nm in a natural silicon substrate. The molecular state, provided by these spatially separated donors, is used to study with exquisite precision the impact of confinement potential on the electronic and spin properties of qubits. Unique spin filling measurements, performed on up to five electrons, confirm how electrons are shared between both sites of the molecule, forming hybridized molecular states. The precise atomic locations of the donor atoms in the silicon lattice are determined by combining the experimental electron spin resonance spectra and the state-of-the-art atomistic modeling of multi-electron wave-functions in presence of realistic electric fields. The donor molecule studied in this work exhibits excellent qubit properties and addresses the impact that the confinement potential has, at the atomic scale, on the desired properties of electron spin qubits. 相似文献
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《Applied Superconductivity, IEEE Transactions on》2009,19(1):2-13
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Alberto Pretel John H. Reina William R. Aguirre-Contreras 《Microelectronics Journal》2008,39(3-4):682-684
Within the density matrix formalism, we report on the quantum control of the excitonic coherences in quantum dots coupled to a single mode field resonant semiconductor cavity. We use an external classical laser field to drive the dynamical response of the excitonic states. Dissipation mechanisms associated with the cavity field and the excitonic states are explicitly included in the model. Our numerical simulations of the excitonic dynamics are in good agreement with recent experimental reports. Furthermore, we compute and show how to tailor such a dynamics in the presence of the laser field by means of controlling the detuning between the laser and the cavity field frequencies. The results are analyzed with a view to implementing quantum control of local qubit operations. 相似文献
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Fariel Shafee 《Microelectronics Journal》2006,37(11):1321-1324
We present a simple method of obtaining a completely entangled lattice of qubits, using a modified form of the controlled-NOT quantum gates connecting nearest neighbors, which we have studied earlier. In this fully entangled case, for computational economy a slightly modified form of the c-NOT gate is used, which inverts the phase as well as the state of the controlled qubit when the controlling qubit is excited. It too gives a manifestly unitary transition matrix for each updating of the network, while keeping all the numbers produced in the operations real. The dynamics leads to a completely entangled state of the qubits. Simulation shows a surprising property of the dynamics of the network, viz. the possibility of obtaining the initial state by a method of back-projecting the complicated entangled states that evolve after many updatings of the entire network. We prove that it is not possible for a sequence of unitary operators working on a net to make it move from an aperiodic regime to a periodic one, unlike some classical cases where phase-locking happens in course of evolution. However, we show that it is possible to introduce periodic orbits to sets of initial states, which may be useful in forming dynamic pattern recognition systems. 相似文献
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量子位叠加态的防错纠错编码 总被引:10,自引:2,他引:8
提出用单个量子位的叠加态进行量子编码,采用分组纠错方法,设置纠错量子线路;用8个量子们编码时,建立同态量子位对模型,简化了量子编码。 相似文献
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A scheme to generate terahertz radiation by an array of quantum dots localized at the center of a semiconducting heterostructure is developed. Electrons are injected into the active part due to the source and drain Fermi energy difference induced by a dc electric field. The structure is placed inside a microcavity stimulating the electronic transition in the quantum dots accompanied by the emission of a photon to the cavity mode. This process is optimized using the filters formed by the quantum wells, which facilitate the electron density concentration in a quantum dot. The electromagnetic field radiated by the cavity in the waveguide can be used for a local effect on the charge qubits. The parameters of such a source depend on the working characteristics of the quantum dots and cavity. 相似文献
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A theoretical investigation is presented into the coherent dynamics of a charge qubit in the form of two tunnel-coupled quantum dots containing a single electron, with the logic states represented by electron orbitals localized at the quantum dots. Analytical expressions are derived for the evolution of a one-or two-qubit system in an applied field. The system and field parameters are evaluated in terms of performing basic one-qubit operations. The possibility is explored for implementing the CNOT operation in a two-qubit system driven by error-free or error-prone control pulses. 相似文献
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基于超导量子电路系统,我们提出了通过量子非 破坏性测量的方法来实现光子的量子态制备。由约 瑟夫森结构成的两能级超导量子比特,在与腔耦合的情况下,其能级会产生斯塔克位移,位 移的大小与腔 内光子数成正比。利用超导量子比特能级位移受到腔内光子影响这一性质,在波导与超导量 子比特耦合的 情况下,通过波导中光子透过率的测量,从而判断出腔内的光子数。这种测量方式对腔内的 光子不产生影 响,因而是量子非破坏性测量,进而实现腔内光子的量子态制备。此外,我们还讨论了相关 参数对制备效 果的影响,在此基础之上,提出了通过反馈重复测量的方法来提高制备效率,从而实现目标 量子态的快速制备。 相似文献
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Programmable quantum logic gates using teleportation with non-maximally entangled states 总被引:1,自引:0,他引:1 下载免费PDF全文
A scheme is proposed for involving programmable quantum logic gates via teleportation,which is a unique technique in quantum mechanics.In our scheme,considering the inevitable decoherence caused by noisy environment,the quantum states are not maximally entangled.We show the implementation of single qubit quantum gates and controlled-NOT(C-NOT) gate,which are universal quantum gates.Hence,any quantum gate can be implemented by using teleportation withnon-maximally entangled states.Furthermore,two schemes in differet connections of universal gates are proposed and compared,and our results show the parallel connection outperforms the cascade connection. 相似文献
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提出了一种利用两粒子最大纠缠态和三粒子部分纠缠态作为量子通道,成功实现量子隐形传态的方案,其中作为通道的三粒子部分纠缠态可以由一般的GHZ态经过一个H门和CNOT门得到,并且与以往一般的三粒子通道相比,它可以传输更多的信息给接收者。发送者Alice在以Bell基为底的基础上对手中的粒子进行测量,然后把测量结果通过经典信道告诉控制者Charlie,Charlie以非最大纠缠Bell基为底,对粒子进行测量,把结果告诉接收者Bob,最后Bob对粒子进行相应的幺正变换,即可得到最初态。此方案采用非最大纠缠态作为量子通道,在Charlie的控制下,有可能实现传输概率100%的完美传输。 相似文献
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本文给出了量子门的符号化表示形式,将n量子线路表示成一个控制位符号向量和一个低阶受控量子门的组合,避免了使用高维矩阵的巨大存储开销.对无循环格雷码生成算法进行扩展,提出了n元k定位二进制数生成算法.提出了快速量子仿真算法FQSA,将输入状态向量分组,用同一酉算子对各组进行矩阵向量乘积运算,从而快速产生输出状态向量.相比其他通用量子仿真算法,FQSA节省了存储空间,并具有最优的时间复杂度.仿真QFT表明,较当前最好的分治算法,FQSA极大降低了运行时间,提高了可仿真量子比特数. 相似文献
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