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1.
We firstly give a nonlocal method for generating pair coherent state with two traveling wave fields in distinct districts. The experimental scheme proposed is based on a two-mode photon number matching process, which employs weak cross-Kerr media and on/off detection. Then we discuss the details for implementing this scheme, showing that it is robust against the low quantum efficiency of photon detectors and offers nearly perfect pair coherent states. Finally, we show how a two-mode Schrödinger cat state and a generalized two-mode correlated photon number state can be prepared via this matching process.  相似文献   

2.
This Letter is devoted to the building of coherent states from arguments based on classical action–angle variables. First, we show how these classical variables are associated to an algebraic structure in terms of Poisson brackets. In the quantum context these considerations are implemented by ladder type operators and a structure known as spectrum generating algebra. All this allows to generate coherent states and thereby the correspondence of classical–quantum properties by means of the aforementioned underlying structure. This approach is illustrated with the example of the one-dimensional Pöschl–Teller potential system.  相似文献   

3.
We investigate coherent exciton transitions in GaAs/Al x Ga1–x As quantum wells using subpicosecond four-wave-mixing spectroscopy. In a first part, we show that the four-wave-mixing lineshape deviates considerably from earlier predictions when the detailed structure of the excitons is taken into account, and we study the density dependence and excitation energy dependence in detail. In a second part, we discuss the observation of quantum beats due to the coherent superposition of different excitonic transitions and show how the analysis of the lineshape can yield information about relaxation processes.Dedicated to H.-J. Queisser on the occasion of his 60th birthday  相似文献   

4.
In this paper, we study quantum teleportation of atomic states via a hybrid entangled state (HES) involving an atom and a cavity field. And we investigate how to implement controlled phase (CP) gates between atomic internal states and coherent states of cavity field. We also discuss the methods of distinguishing coherent states |±α〉in a cavity. Finally, a brief discussion about the feasibility of this scheme in experiment is presented.  相似文献   

5.
Generation of pair and bi-pair coherent states   总被引:1,自引:0,他引:1  
A method for the generation of pair coherent states of a two-mode cavity field is presented. It is based on the nondegenerate two-photon Jaynes-Cummings model. We also show how we can produce bi-pair coherent states of four modes located in two cavities using such a model.  相似文献   

6.
In this paper, we introduce the definition of a new kind of continuous-variable-type entangled coherent states, called double-mode excited entangled coherent states through acting creation operators on the double-mode entangled coherent states. We briefly present how to produce them from the two mode ECSs through an interaction between laser and atoms. We further focus on studying the fidelity of the states and discussing the influence of photon excitations on fidelity.  相似文献   

7.
丁达夫 《声学学报》1980,5(4):270-278
在无限均匀介质中,能量集中辐射问题已在“指向性”的几何概念下解决。而在浅海分层介质中,能量集中辐射自然是与浅海传播算子相匹配的相干辐射。
本文就三种典型水文条件分析了垂直线形相干声源的相干辐射增益:
1.在均匀层,Weston C区内,相干辐射增益是每10倍程5dB,相当于相干声源在Weston B区和Weston C区保持波导传播;
2.在负梯度,当相干声源的聚焦深度对准浅处目标,可以获得显著的相干辐射增益;
3.在负跃层,相干辐射穿透跃层和束缚层下波的能力显著强于点源辐射的相应能力;
4.相干声源无单程相关损失。  相似文献   

8.
We describe a mathematical formalism and numerical algorithms for identifying and tracking slowly mixing objects in nonautonomous dynamical systems. In the autonomous setting, such objects are variously known as almost-invariant sets, metastable sets, persistent patterns, or strange eigenmodes, and have proved to be important in a variety of applications. In this current work, we explain how to extend existing autonomous approaches to the nonautonomous setting. We call the new time-dependent slowly mixing objects coherent sets as they represent regions of phase space that disperse very slowly and remain coherent. The new methods are illustrated via detailed examples in both discrete and continuous time.  相似文献   

9.
It has been recently demonstrated that a pump pulse can generate coherent charge fluctuations in a superconductor through a stimulated Raman process [Mansart, et al., Proc. Natl. Acad. Sci. USA 110, 4539 (2013)]. Here, we present a tutorial review of the basic phenomena involved and show how the technique bears a strong analogy with nuclear magnetic resonance and electron paramagnetic resonance. The reflectivity of the system gets modulated by the coherent charge fluctuation of the condensate. A resonance at the Mott scale allows to identify a high-energy excitation which is coupled to the superconducting quasiparticles.  相似文献   

10.
We show how increasing spatial interaction leads to the merging of coherent structures from chaos in some systems of coupled map lattices. This phenomenon reflects the arising of new ground states in the corresponding model of statistical mechanics. If we further increase the coupling then, new ground states appear showing the coexistence of a large-scale coherent structure with a small-scale chaotic motion. This allows us to propose a generalization of the notion of spatial intermittency.  相似文献   

11.
WANG Bo 《理论物理通讯》2008,49(6):1599-1602
We propose a potential scheme of preparing Schrödinger-cat state of the cavity mode by placing an rf-superconducting quantum interference device (rf-SQUID) in a single-mode microwave cavity. By properly adjusting the detuning and the strength regarding the radiation fields, we show how to generate single-mode Schrödinger-cat state. Generalizing this method we discuss the generation of the engtangled coherent states. The experimental feasibility of our scheme is discussed under consideration of the cavity decay.  相似文献   

12.
Longo P  Busch K 《Optics letters》2012,37(11):1793-1795
We present a theoretical analysis of pulse propagation in a waveguide with a side-coupled Kerr nonlinear cavity. As a specific application, we demonstrate how the nonlinearity has a profound influence on transport properties of a photon-added coherent state. We find that the fields provided by the coherent states facilitate a tunable nonlinearity on the few-photon level, allowing for a robust gating of single photons.  相似文献   

13.
F. Bagarello 《Physics letters. A》2008,372(41):6226-6231
We propose an extension of supersymmetric quantum mechanics which produces a family of isospectral Hamiltonians. Our procedure slightly extends the idea of intertwining operators. Several examples of the construction are given. Further, we show how to build up vector coherent states of the Gazeau-Klauder type associated to our Hamiltonians.  相似文献   

14.
We derive analytical expressions for the single mode quantum field state at the individual output ports of a beam splitter when a single-photon Fock state and a coherent state are incident on the input ports. The output states turn out to be a statistical mixture between a displaced Fock state and a coherent state. Consequently we are able to find an analytical expression for the corresponding Wigner function. Because of the generality of our calculations the obtained results are valid for all passive and lossless optical four port devices. We show further how the results can be adapted to the case of the Mach-Zehnder interferometer. In addition we consider the case for which the single-photon Fock state is replaced with a general input state: a coherent input state displaces each general quantum state at the output port of a beam splitter with the displacement parameter being the amplitude of the coherent state.  相似文献   

15.
We show how the time-continuous coherent state path integral breaks down for both the single-site Bose-Hubbard model and the spin-path integral. Specifically, when the Hamiltonian is quadratic in a generator of the algebra used to construct coherent states, the path integral fails to produce correct results following from an operator approach. As suggested by previous authors, we note that the problems do not arise in the time-discretized version of the path integral.  相似文献   

16.
We propose a scheme for measuring the Berry phase in the vibrational degree of freedom of a trapped ion. Starting from the ion in a vibrational coherent state we show how to reverse the sign of the coherent state amplitude by using a purely geometric phase. This can then be detected through the internal degrees of freedom of the ion. Our method can be applied to preparation of entangled states of the ion and the vibrational mode.  相似文献   

17.
Superradiance, the enhanced collective emission of energy from a coherent ensemble of quantum systems, has been typically studied in atomic ensembles. In this work we study theoretically the enhanced emission of energy from coherent ensembles of harmonic oscillators. We show that it should be possible to observe harmonic oscillator superradiance for the first time in waveguide arrays in integrated photonics. Furthermore, we describe how pairwise correlations within the ensemble can be measured with this architecture. These pairwise correlations are an integral part of the phenomenon of superradiance and have never been observed in experiments to date.  相似文献   

18.
We study the effect of a strong, oscillating driving field on the dynamics of ultracold bosons held in an optical lattice. Modeling the system as a Bose-Hubbard model, we show how the driving field can be used to produce and maintain a coherent atomic current by controlling the phase of the intersite tunneling processes. We investigate both the stroboscopic and time-averaged behavior using Floquet theory, and demonstrate that this procedure provides a stable and precise method of controlling coherent quantum systems.  相似文献   

19.
20.

In this article, we propose a new kind of quantum states based on acting the number operator M times \( {\hat{n}}^M \) on the coherent state. We term this state the Mth coherent state, based on the value of the power M. We find that it is strongly similar to the coherent state as the analysis of the photonic statistical distributions and the overlap with the coherent state illustrate. Also, we find that it asymptotically reaches the minimum uncertainty and has a localized behavior in the Husimi function. However, in contrast to coherent state, the Mth coherent state has strong nonclassical features such as antibunching and squeezing for a relatively long range. Other parameters and measurements are discussed and studied. Finally, we highlight the similarity between the higher orders of the near coherent states and the Mth coherent states in order to potentially generate our proposed state.

  相似文献   

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