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991.
This paper proposes a scheme for entanglement concentration of unknown triparticle W class states with a certain probability. This protocol is mainly based on the coincidences of single-photon detectors and requires single-photon detectors and linear optical elements. The scheme is feasible within current technology. 相似文献
992.
We have investigated the evolution of the atomic quantum entropy and the entanglement of atom-photon in the system with competing k-photon and l-photon transitions by means of fully quantum theory, and examined the effects of competing photon numbers (k and l), the relative coupling strength between the atom and the two-mode field (A/g), and the initial photon number of the field on the atomic quantum entropy and the entanglement of atom-photon. The results show that the multiphoton competing transitions or the large relative coupling strength can lead to the strong entanglement between atoms and photons. The maximal atom-photon entanglement can be prepared via the appropriate selection of system parameters and interaction time. 相似文献
993.
A controlled quantum teleportation scheme of an N-particle unknown state via three-particle W1 states 下载免费PDF全文
In this paper a controlled quantum teleportation scheme of an N-particle unknown state is proposed when N groups of three-particle W1 states are utilized as quantum channels. The quantum information of N-particle unknown state is transmitted from the sender to the recipient under the control of all supervisors. It can be realized with a certain probability. After the sender makes Bell-state measurements and the supervisors perform the computational basis measurements, the recipient will introduce auxiliary particles and carry out unitary transformations depending on classical information from the sender and the supervisors. Finally, the computational basis measurement will be performed by the recipient to confirm whether the teleportation succeeds or not. The successful completion of the scheme relies on all supervisors' cooperation. In addition, the fidelity and security of the scheme are discussed. 相似文献
994.
质量起源——量子色动力学与质量起源 总被引:1,自引:0,他引:1
……有读者可能会问:我们是不是离题了?既然量子色动力学中的胶子是无质量的,而夸克虽然有质量,但其质量是不可约化的。那么,量子色动力学与质量起源这一主题又能有什么关系呢?应该说,这是一个很合理的疑问。但量子色动力学的奇妙之处就在于,它形式上异常简洁,内涵却惊人地丰富。它宛如一坛绝世的佳酿,越品就越是回味无穷。在谈论质量起源问题的时侯,人们往往把注意力放在包含希格斯机制的电弱统一理论上,因为希格斯机制在登场伊始就打出了质量产生机制的响亮广告。但事实上我们将会看到,看似与质量起源问题无关的量子色动力学对这一问题有着非常独特而精彩的回答,从某种意义上讲,这一回答才是标准模型范围内的最佳回答。…… 相似文献
995.
996.
We present an experimentally feasible one-step discrimination scheme on Bell bases with trapped ions, and then generalize it to the case of N-ion Greenberger-Horne-Zeilinger (GHZ) bases. In the scheme, all the orthogonal and complete N-ion GHZ internal states can be exactly discriminated only by one step, and thus it takes very short time. Moreover, the scheme is insensitive to thermal motion and dose not require the individual addressing of the ions. The Bell-state and GHZ-state one-step discrimination scheme can be widely used in quantum information processing based on ion-trap set-up. 相似文献
997.
Ordered InAs Quantum Dots with Controllable Periods Grown on Stripe-Patterned GaAs Substrates 下载免费PDF全文
GaAs (001) substrates are patterned by electron beam lithography and wet chemical etching to control the nucleation of lnAs quantum dots (QDs). InAs dots are grown on the stripe-patterned substrates by solid source molecular beam epitaxy. A thick buffer layer is deposited on the strip pattern before the deposition of InAs. To enhance the surface diffusion length of the In atoms, InAs is deposited with low growth rate and low As pressure. The AFM images show that distinct one-dimensionally ordered InAs QDs with homogeneous size distribution are created, and the QDs preferentiMly nucleate along the trench. With the increasing amount of deposited InAs and the spacing of the trenches, a number of QDs are formed beside the trenches. The distribution of additional QDs is long-range ordered, always along the trenchs rather than across the spacing regions. 相似文献
998.
fficient Scheme for Implementing a Fredkin Gate via Resonant Interaction with Two-Mode Cavity Quantum Electrodynamics 总被引:1,自引:0,他引:1 下载免费PDF全文
A scheme for implementing a Fredkin gate with an atom sent through a microwave cavity is proposed. The scheme is based on the resonant atom-cavity interaction so that the gating time is sharply short, which is important in view of decoherence. 相似文献
999.
Quantum Phase Transition and Ferromagnetic Spin Correlation in Parallel Double Quantum Dots 下载免费PDF全文
We investigate electronic transport through a parallel double quantum dot (DQD) system with strong on-site Coulomb interaction, as well as the interdot tunnelling. By applying numerical renormalization group method, the ground state of the system and the transmission probability at zero temperature are obtained. For a system of quantum dots with degenerate energy levels and small interdot tunnel coupling, the spin correlations between the DQDs is ferromagnetic, and the ground state of the system is a spin-1 triplet state. The linear conductance will reach the unitary limit (2e^2/h) due to the Kondo effect at low temperature. As the interdot tunnel coupling increases, there is a quantum phase transition from ferromagnetic to anti-ferromagnetic spin correlation in DQDs and the linear conductance is strongly suppressed. 相似文献
1000.
Remote interactions between two d-dimensional distributed quantum systems: nonlocal generalized quantum control-NOT gate and entanglement swapping 下载免费PDF全文
We present a systematic simple method to implement a generalized quantum control-NOT (CNOT) gate on two d-dimensional distributed systems. First, we show how the nonlocal generalized quantum CNOT gate can be implemented with unity fidelity and unity probability by using a maximally entangled pair of qudits as a quantum channel. We also put forward a scheme for probabilistically implementing the nonlocal operation with unity fidelity by employing a partially entangled qudit pair as a quantum channel. Analysis of the scheme indicates that the use of partially entangled quantum channel for implementing the nonlocal generalized quantum CNOT gate leads to the problem of 'the general optimal information extraction'. We also point out that the nonlocal generalized quantum CNOT gate can be used in the entanglement swapping between particles belonging to distant users in a communication network and distributed quantum computer.[第一段] 相似文献