Chen Ai-Xi

Synthesis, Tribological and Hydrolysis Stability Study of Novel Benzotriazole Borate Derivative

Benzotriazole and borate derivatives have long been used as multifunctional additives to lubricants. A novel, environmentally friendly additive borate ester (NHB), which contains boron, ethanolamine, and benzotriazole groups in one molecule, was synthesized by a multi-step reaction, and its tribological properties in rapeseed oil (RSO) were investigated by a four-ball tribometer. The hydrolysis stability of the additive was investigated by half-time and open observation methods, and the mechanism of hydrolysis stability was discussed through Gaussian calculation. The novel compound NHB showed excellent performance under extreme pressure, against wearing, and in reducing friction, and its hydrolysis time is more than 1,220 times, which is better than that of triethyl borate. The mass ratio of NHB is bigger than that of the mixed liquid of triethyl borate and ethanolamine. The lone electron of amino N atoms forms a coordination effect with the B atom to compensate for the shortage of electrons in the B atom and to improve the hydrolysis stability of NHB. The surface morphology and the traces of different elements in the tribofilms formed with 1.0 wt.% NHB in were detected with scanning electron microscopy(SEM), energy dispersive X-ray spectroscopy (EDX)and X-ray photoelectron spectroscopy(XPS). The results shown that the additive caused a tribochemical reaction with the steel ball surface during the lubricating process. A mixed boundary lubrication film that contains organic nitrogen and inorganic salts, such as BN, B2O3, FeOx, Fe–O–B, and FeB, was also formed, and the formation of the lubricating film improved the tribological properties of the base oil.

Distillation of bi-partite entanglement from W state with cavity QED

Following the theoretical protocol described by Fortescue and Lo [Fortescue B and Lo H K 2007 Phys. Rev. Lett. 98 260501], we present a scheme in which one can distill maximally entangled bi-partite states from a tri-partite W state with cavity QED. Our scheme enables the concrete physical system to realize its protocol. In our scheme, the rate distillation also asymptotically approaches one. Based on the present cavity QED techniques, we discuss the experimental feasibility.

Influences of control coherence and decay coherence on optical bistability in a semiconductor quantum well

We discuss the influences of two different types of mechanisms of quantum coherence on optical bistability in a semiconductor quantum well structure. In the first mechanism, only quantum coherence induced by the resonant coupling of a strong control laser is considered. In the second mechanism, the decay coherence is taken into account under the condition where the control field is weak. In two different cases, optical bistability can be obtained through choosing appropriate physical parameters. Our studies show quantum coherence makes the optical nonlinear effect of the system become stronger, which takes an important role in the process of generating optical bistability. A semiconductor quantum well with flexibility and easy integration in design could potentially be exploited in real solid-state devices.

High efficient scheme for remote state preparation with cavity QED

In this paper, a scheme is proposed for remote state preparation (RSP) with cavity quantum electrodynamics (QED). In our scheme, two observers share two-atom nonmaximally entangled state as quantum channels and can realize remote preparation of state of an atom. We also propose a generalization for remote preparation of N-atom entangled state by (N+1)-atom GHZ-like state (N ≥ 2). By this scheme, one single-atom projective measurement is enough for the RSP of a qubit or N-atom entangled state, and the probability of success for RSP is unity. Furthermore, we have considered the case where observers use W-like state as quantum channels to realize RSP of a qubit. We compare our scheme with existing ones.

Influence of the Stark Shift on Entanglement Sudden Death and Birth in Cavity QED

We investigate the entanglement dynamics of two two-level atoms interacting with two vacuum fields of two spatially separated cavities with the Stark effects by employing the concurrence. It is shown that the entanglement sudden death (ESD) and birth (ESB) could be controlled by adjusting the Stark-shift parameters. If the Stark-shift parameters are chosen appropriately, then ESD and ESB phenomena will appear. In addition, the appearance of ESD before or after ESB depends on the Stark-shift values.

Tribological and antioxidation synergistic effect study of sulfonate-modified nano calcium carbonate.

A middle base number sulphonate-modified nano calcium carbonate (SMC) with an average size of 35 nm was synthesized, and its tribological and antioxidation synergistic behaviors with ashless antioxidant N-phenyl-α-naphthylamine (T531) in hydrogenated oil (5Cst) were evaluated. The results demonstrate that adding this synethesized additive even at a low amount (<2.0 wt.%) can evidently improve its load-carrying capacity by 1.5 times and enhance its antiwear performance; in addition, the friction-reducing effect of additive in the high load was better than that in low load. The SMC have a good synergistic antioxidation effect with T531, which verifies the nano calcium carbonate compound was a kind of multifunctional and high-performance additive. The chemical composition of the rubbing surface which formed on the boundary film was analyzed by using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results indicating that the excellent antiwear and load-carrying performance could be attributed to the forming of boundary lubrication film which composed of calcium carbonate, oxides, ferrites, sulphide and FeSO4, and so on. Its ability to increase oxidation free energy of base oil is the main reason for increasing its antioxidant collaboration property with ashless antioxidant T531.

Teleportation of N-qubit W State without Bell-State Measurement via Selective Resonant Interaction in Cavity QED

We present a scheme in which the N-atom W state is teleported by employing the selective interaction of a cavity field with a driven three-level atom in the A configuration and detecting a single atom in one of the ground states. The long-lived W state is teleported from atom A to atom B when the atoms B and A are sent through a cavity successively and atom A is then detected. The advantage is that the present one does not involve the Bell-state measurement and is robust against the atomic spontaneous emission.

Optical bistability and multistability in a three-level Δ-type atomic system under the nonresonant condition

Under nonresonant condition,we theoretically investigate the optical bistability(OB) and multistability(OM) behaviors in a three-level ∧-type system using a microwave field driving a hyperfine transition between two lower states inside the unidirectional ring cavity.The results show that the optical bistability behavior can be controlled by adjusting the intensity and the frequency detuning of the coupling field,respectively.It is also found that the microwave field plays an important role in achieving the multistability.The influence of the atomic cooperation parameter on the OM behavior is discussed at last.

Remote Operation on Quantum State Among Multiparty

In this paper, a scheme is proposed for performing remote operation on quantum state among multiparty. We use three-particle GHZ state as quantum channels to prepare a state operator, which describes quantum correlation between states and operations. Based on the special characteristic of the state operator, observers can perform unitary operation on a system that is away from observers. Our studies show this process is deterministic. We further consider remote operation among N spatially distributed observers, and the results show the successful realization of remote operation needs collective participation of N parties, that is, there exists strong correlation among multiparty. In addition, we investigate the case in which observers share a three-particle W state as quantum channels to perform remote operation and studies find this process is probabilistic.

Unconditional secure two-way quantum dense key distribution

In this paper, we present a two-way quantum dense key distribution protocol. With double check modes, our scheme is secure regardless of the presence of noises. And with a quantum teleportation process, secret message can be encoded deterministically even if the quantum channel is highly lossy. Therefore, our scheme can be used in a realistic quantum channel regardless of the presence of noises and channel losses.