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Optimal two-qubit operation is of significance to quantum information processing. An efficient scheme is proposed for realizing the shortcut to adiabatic two-qubit state swap in a superconducting circuit quantum electrodynamics (QED) via effective drivings. Two superconducting qutrits are coupled to a common cavity field and individual classical drivings. Based on two Gaussian-type Rabi drivings, two-qubit state swap can be adiabatically implemented within a reduced three-state system. To speed up the operation, these two original Rabi drivings are modified in the framework of shortcuts to adiabaticity, instead of adding an extra counterdiabatic driving. Moreover, owing to a shorter duration time, the decoherence effects on the accelerated quantum operation can be mitigated significantly. The strategy could offer an optimized method to construct fast and robust quantum operations on superconducting qubits experimentally.

In this paper, we have studied the evolution curve of two-level atomic system that the initial state is excited state. At the different of environmental reservoir models, which include the single Lorentzian, ideal photon band-gap, double Lorentzian and square Lorentzian reservoir, we researched the influence of these environmental reservoir models on the evolution of energy level population. At static no modulation, comparing the four environmental models, the atomic energy level population oscillation of square Lorentzian reservoir model is fastest, and the atomic system decoherence is slowest. Under dynamic modulation, comparing the photon band-gap model with the single Lorentzian reservoir model, no matter what form of dynamic modulation, the time of atoms decay to the ground state is longer for the photonic band-gap model. These conclusions make the idea of using the environmental change to modulate the coherent evolution of atomic system become true.

In this paper, we have studied the multiphoton transition Jaynes-Cummings model (N = 1, 2, 3, 4, 5, 6), and researched the effect of initial state superposition coefficient $C_{1}$ , the initial photon number n, the transition photon number N, and the quantum discord $\delta $ on the quantum entanglement degrees, and given the quantum entanglement degrees curves with time evolution. We obtain some results, which should have important significance in the quantum computing and quantum information.

With the nonlinear Jaynes-Cummings model, we have studied the atom and light field quantum entanglement of multiphoton transition in nonlinear medium, and researched the effect of the transition photon number N and the nonlinear coefficient χ on the quantum entanglement degrees. We have given the quantum entanglement degrees curves with time evolution, we find when the transition photon number N increases, the entanglement degrees oscillation get faster. When the nonlinear coefficient α > 0, the entanglement degrees oscillation get quickly, the nonlinear term is disadvantage of the atom and light field entanglement, and when the nonlinear coefficient α

In this paper, we have proposed S U(2) non-Abelian electromagnetism gauge theory. In the theory, photon has self-interaction and interaction between them, which can explain photon entanglement phenomenon in quantum information. Otherwise, we find there are three kinds photons γ +, γ − and γ 0, they have electric charge + e γ , − e γ and 0, respectively, these prediction are accordance with some experiment results.

Entanglement is a fundamental feature of quantum theory as well as a key resource for quantum computing and quantum communication, but the entanglement mechanism has not been found at present. We think when the two subsystems exist interaction directly or indirectly, they can be in entanglement state. such as, in the Jaynes-Cummings model, the entanglement between the atom and the light field comes from their interaction. In this paper, we have studied the entanglement mechanism of electron-electron and photon-photon, which are from the spin-spin interaction. We found their total entanglement states are relevant both space state and spin state. When two electrons or two photons are far away, their entanglement states should be disappeared even if their spin state is entangled.

In this paper, we give two spinor wave equations of free electromagnetic field, corresponding to the reducibility and irreducibility representations D (10)+D (01) and D (10) of the proper Lorentz group, which are the differential equations of space-time one order. The spinor equations are covariant and are equivalent to Maxwell equations.

In this paper, we study two-photon interference with the approach of photon quantum theory, with specific attention to the two-photon interference experiment carried out by Milena D'Angelo et al. (Phys. Rev. Lett 87:013602, 2001). We find the theoretical result is accordance with experiment data.

In this paper, we propose finite temperature Dirac equation, which can describe the quantum systems in an arbitrary temperature for a relativistic particle of spin-1/2. When the temperature T=0, it become Dirac equation. With the equation, we can study the relativistic quantum systems in an arbitrary temperature., Comment: arXiv admin note: text overlap with arXiv:1005.2751, arXiv:hep-ph/0004125, arXiv:hep-ph/0005272 by other authors

To enhance the efficiency of eavesdropping detection in the “Ping-Pong” protocol, an improved “Ping-Pong” protocol based on five-qubit GHZ state and classical CNOT operation is presented. The five-qubit GHZ state is used to detect eavesdroppers, and the classical CNOT operation served as one-time-pad is used to ensure the security of the protocol. In the security analysis, the method of the entropy theory is introduced, and three detection strategies are compared quantitatively by using the constraint between the information eavesdroppers can obtain and the interference introduced. If the eavesdropper obtains the same amount of information, she must face a larger detection probability in the proposed scheme than the other two, and if obtains all the information, the detection rate of the original Ping-Pong protocol is 50%; the second protocol which used two particles of EPR pair as detection particles is also 50%; while the presented protocol is 92%. At last, the security of the proposed protocol is discussed. The analysis results indicate that the protocol in this paper is more secure than the other two.

We propose some nonlinear Schrodinger equations by adding some higher order terms to the Lagrangian density of Schrodinger field, and obtain the Gross-Pitaevskii (GP) equation and the logarithmic form equation naturally. In addition, we prove the coefficient of nonlinear term is very small, i.e., the nonlinearity of Schrodinger equation is weak.

We provide a quantum approach description of neutron single and double-slit diffraction, with specific attention to the cold neutron diffraction ($\lambda \approx 20$\AA) carried out by Zeilinger et al. in 1988. We find the theoretical results are good agreement with experimental data., Comment: 10 pages

In this paper, we give the quantum wave equations of single photon when it is in the free or medium space. With these equations, we can study light interference and diffraction with quantum approach. Otherwise, they can be applied in quantum optics and photonic crystal., Comment: 8 pages, 0 figures