Probabilistic teleportation of an arbitrary pure state of two atoms

In the context of microwave cavity QED, this paper proposes a new scheme for teleportation of an arbitrary pure state of two atoms. The scheme is very different from the previous ones which achieve the integrated state measurement, it deals in a probabilistic but simplified way. In the scheme, no additional atoms are involved and thus only two atoms are required to be detected. The scheme can also be used for the teleportation of arbitrary pure states of many atoms or two-mode cavities.     

Nonclassical Properties in the Resonant Interaction of a Three Level A-type Atom with Two-mode Coherent state

A potential scheme is proposed to deterministically generate complete sets of entangled photons in the context of cavity quantum electrodynamics （QED）. The scheme includes twice interactions of atoms with cavities, in which the first interaction is made in two-mode optical cavities and the second one exists in a microwave cavity. In the optical cavities the atoms are resonant with the cavity modes, while the detuned interaction of the atoms with a singlemode of the microwave cavity is driven by a classical field. The favorable features of our scheme include ： （ 1 ） it is very straightforward in implementation because we carry out the scheme by only sending atoms through the cavities. The requirement for the implementation is very close to the reach of current cavity QED techniques. （2） The com- plete set of the entangled two- or more-photon states can be generated deterministically by our scheme, and the implementation time remains constant with the size of the entangled photon states. （3） Our scheme is more efficient than previous proposals with cavities, and the generated photons may be collected much more efficiently, due to cavities, than previous proposals by spontaneous emission.     

Non-Geometric Conditional Phase Gate by Quantum Zeno Dynamics in Laser-Excited Nitrogen-Vacancy Centers

Based on the quantum Zeno dynamics,we propose a two-qubit non-geometric conditional phase gate between two nitrogen-vacancy centers coupled to a whispering-gallery mode cavity.The varying phases design of periodic laser can be used for realizing non-geometric conditional phase gate,and the cavity mode is virtually excited during the gate operation.Thus,the fidelity of the gate operation is insensitive to cavity decay and the fluctuation of the preset laser intensity.The numerical simulation with a realistic set of experimental parameters shows that the gate fidelity 0.987 can be within reached in the near future.     

Cavity loss induced generation of W states

The existence of decoherence-free subspace （DFS） has been discussed widely. In this paper, we propose an alternative scheme for generating the four-atom W states by manipulating DF qubits. The atoms are divided into two pairs and trapped in two separate optical cavities. Manipulation of atoms within DFS may generate a two-atom maximally entangled state in an individual cavity, which is a stable state. After driving the system out of DFS, the atoms will interact resonantly with the cavity field. The photons leaking from the cavities interfere at the beamsplitter, which destroys which-path information, and are finally detected by one of the detectors, leading to the generation of a W state. In addition, the numerical simulation indicates that the fidelity of the prepared state can, for a very wide parameter regime, be very close to unity.     

Nonclassical properties in the resonant interaction of a three level Λ-type atom with two-mode field in coherent state

In this paper, we study the nonclassical properties of the electromagnetic field resulting from the interaction of a three-level Λ-type atom with a two-mode field initially in the coherent state, such as squeezing properties and sub-Poisson statistics. We show that the squeezing can be enhanced by selective atomic measurement.     

Faithfully probabilistic teleportation of an unknown atomic state and cavity field state with a single measurement

This paper shows that, based on the single-photon JC model depicting the resonant interaction of a two-level atom with a single cavity mode, an unknown atomic state and cavity photon superposition state can be faithfully telcported with only a single measurement. The scheme is probabilistie, its success lies on the event that the sender atom （or the medi-atom, for teleportation of cavity field state） is detected in the higher state. The scheme is in contrast to the previous ones of using a maximally two-particle entangled state as quantum channel.[第一段]     

Generation of entanglement molecules via weak coherent field in cavity QED

This paper presents a method for generating entanglement molecules, which is introduced by Dur (2001 Phys. Rev. A). In this scheme, N ladder-type three-level atoms are sent through a resonant weak coherent cavity field, then the system states are measured. And the system field may collapse onto some possible types of entanglement molecules. Meanwhile it discusses about the interaction time from the experimental point of view, and compare the result with the previous scheme proposed by Huang (2004 J. Phys. B: At. Mol. Opt. Phys.).     

Engineering three-dimensional maximally entangled states for two modes in a bimodal cavity

An alternative scheme is proposed for engineering three-dimensional maximally entangled states for two modes of a superconducting microwave cavity. In this scheme, an appropriately prepared four-level atom is sent through a bimodal cavity. During its passing through the cavity, the atom is coupled resonantly with two cavity modes simultaneously and addressed by a classical microwave pulse tuned to the required transition. Then the atomic states are detected to collapse two modes onto a three-dimensional maximally entangled state. The scheme is different from the previous one in which two nonlocal cavities are used. A comparison between them is also made.