【作者】 王俊；

【导师】 叶柳；

【作者基本信息】 安徽大学 ， 原子与分子物理， 2007， 硕士

【摘要】 量子信息学是量子力学和信息科学结合的产物，它主要是利用微观粒子作为载体，凭借量子力学所特有的一些性质可以解决许多经典信息所不能够完成的信息处理功能，充分显示了经典信息科学所无法比拟的优势。量子信息学主要包括量子通信和量子计算两个部分，量子通信是量子信息学的重要分支，包括量子隐形传送、量子密集编码、量子秘密分享等。在量子信息的研究中，需要对量子信息进行处理，那么量子硬件必不可少。已经提出的方案中，腔量子电动力学(腔QED)方案是其中之一。目前在量子信息处理的过程中，两大主要障碍是量子态的消相干问题和联合Bell态测量的实验实现问题。这两个问题在腔QED方案中都得到了很好的解决。正因为腔QED方案的这一优势，使其成为最有前景的量子硬件设计方案之一。本文将进一步研究腔QED技术在量子信息处理中的应用。当然，我们的目光主要集中在对多量子比特信息的处理上，主要研究多体纠缠态的制备方法和对多量子比特信息的处理，我们的研究主要取得了以下几项成果：1．用不同的腔QED系统制备了多粒子纠缠态：1)基于原子和腔场的大失谐相互作用，我们提出了制备多原子纠缠态的方案，同样我们的方案也可以推广到传送N原子的情况。由于本方案中，原子的跃迁频率和腔场频率是大失谐的，因此，可以有效克服光场消相干影响，而且在原子通过腔的过程中，腔场只是虚激发，不需要在原子和腔之间传递量子信息，这样对腔的品质因子的要求大大的降低了。2)同样是原子和腔场非共振的情况，然而我们附加了一个特定频率的经典场作为驱动，这样也可以得到多原子纠缠态。而且这个方案也可以推广到N个原子的情况。这个方案的优势就在于它对原子的初态没有什么要求，而且操作起来也很简单。2．利用腔QED技术实现了两原子任意态的隐型传送；提出了基于原子和腔场的大失谐相互作用传送未知两原子任意态的方案。我们的方案可以用单原子测量取代原本复杂且难以实现的联合Bell态测量；在原子通过腔的过程中，腔场只是虚激发，不需要在原子和腔场之间传递量子信息，这样可以有效地克服光场消相干影响，因而对腔的品质因子的要求就大大降低了。3．利用腔QED技术实现了一个控制非门操作。在这个方案中，我们按照量子隐形传送的步骤成功地实现了一个控制非门操作。方案中需要用到的联合Bell态测量，我们仍然用大失谐腔加经典场的方法来解决。由于多比特量子门在量子信息处理中非常有用，因此我们的研究是非常有意义的。更多还原

【Abstract】 Quantum information theory is an inter-discipline of quantum mechanics and information theory, which is competent in some of impossible task within the classical information science. Quantum information theory shows the superiorities beyond compare in classical information. Quantum information theory includes quantum computation and quantum communication, quantum communication is a way of effective information transmission using quantum state as information unit, including quantum teleportation, quantum dense coding, quantum secret sharing, etc.In the study of quantum information, to implement quantum information processing means to operate the qubit, then quantum hardware is needed. The kinds of hardware for quantum information are various, and one of them is the Cavity QED. We know that there are two problems in the quantum information processing, one problem is the decoherent of quantum state, and the other is implementing the joint measurement of Bell-state. Both of the two problems are well solved in the scheme of cavity QED. Just because of this advantage, cavity QED becomes one of the most promising candidates serving as hardware of quantum information.In this paper, we will study the applications of the technology of cavity QED in quantum information. Of cause, our view is focus on the study of processing multi-qubit information. We study how to generating the multi-atom entangled state and propose some scheme to processing the quantum information on the two-atom system. The results of our study are mainly given as follows,1. Generate multi-atom entangled states via different cavity QED system,1) We propose a scheme for the generation of multi-atom entanglement via high-detuned cavity QED. This scheme can also be extended to generate the entanglement between N atoms. Because there is a large detuning between the atom and the cavity field, during the interaction within the cavity, the cavity is only virtually excited, thus there is no quantum information transfer between the atomic system and cavity field. So the requirement on the quality factor of the cavity is greatly loosened. 2) We propose another scheme for the generation of multi-atom entanglement via nonresonant cavity QED system. The distinct different from the above scheme is that we apply a classic field with certain frequency to driven the interaction between two atoms when they are sent into the cavity. By this way, we can also obtain the multi-atom entanglement. The advantage of this scheme is that there is no request of the initial states of atoms, and the whole process of the generation is very simple.2. We propose an experimentally feasible scheme for teleportation of unknown two-atom state via nonresonant cavity QED. In our scheme, the joint measurement is replaced by the single-atom measurement, because we apply a classic field with certain frequency to driven the interaction between two atoms when they are sent into the cavity. The successful probability of our scheme is 1.3. We propose a scheme for implement a special control-not (C-not) gate, which is based on the quantum teleportation. Our scheme is also based on the technology of nonresonant cavity QED, thus the joint measurement can be replaced by the single-atom measurement as we apply a classic field to driven the interaction. Because the multi-qubit gate is useful in the quantum information processing, our study is valuable.更多还原