We introduce the bivariate Hermite polynomials Hmn on quantum optics theory,using ［a,a*］=1.We explain the origin of Hmn and derive some operator identities involving Hmn. By virtue of the IWOP method we prove the orthogonal and completeness of Hmn, and using Hmn we derive the P-representation of normal ordered operators.

High order nonclassical properties of the squeezed vacuum state,such as high order squeezing,high order anti-bunching,and the second order sub-Poissonian photon statistics,are investigated.The effects of the squeezing parameter on these nonclassical properties are discussed by numerical calculations.The results obtained show that it displays high order squeezing and the fourth order anti-bunching,and they are all strengthened with increase of the squeezing parameter.On the other hand,it does not display the first,the second,the third anti bunching,as well as the first and the second order sub-Poissonian photon statistics.

We investigate a protocol of the telecloning of 1→M probabilistic quantum cloning of two states,and derive the success probability.Compared with the standard teleportation that is required to use up two particles for transmitting one particle,our protocol can greatly save the number of the sources of entangled states.The protocol can be regarded as a development of the well-known B92 protocol in quantum cryptography.

Quantum interference (QI) and Autler-Townes splitting (ATS) are two different effects in atom-field interaction systems.In an electromagnetically induced transparency (EIT) system,when the intensity of the coupling field is moderate,these two effects exist simultaneously.The coupling field Rabi frequency is generally responsible for distinguishing them,and Akaike information criterion (AIC) can be used to quantificationally determine their relative weights.Here,we investigate the manipulation of QI with dephasing in atomic systems based on AIC method.We find that by adjusting the dephasing rates,the transition between QI and ATS,and the transition between destructive and constructive interference can be observed.The precision control of dephasing can be realized by using the phase correlation between the coupling and probe fields,allowing the changing of the weights of QI and ATS,and the greatly enhancement of QI.This enhancement effect has a practical significance on quantum technology.

For the problem of low speed of data reconciliation in the current continuous-variable quantum key distribution, this paper proposes a multi-dimensional data reconciliation scheme based on GPU and OpenCL heterogeneous computing. Moreover, we fatherly propose a static two-way cross-linked list storage hyperscale LDPC check matrix to meet the special requirements of the OpenCL′s special regulations. Experimental simulation results show that when the code length is 2×105, under the premise of ensuring effective data reconciliation in same code rate, the average decoding rate of the GPU can reach 4.2 times that of the CPU at the expense of sacrificing some precision.

In this paper,we have investigated a system that is composed of a ∧-type three-level atom and a ∨-type three-level atom with a single-mode photon field.Under the initial state of one atom is exticed state and the other one is in the ground state,the evolution of the state vector of the system is delivered.The entanglement between atoms is described by using the negative eigenvalues of the partially transposed density matrix,the effects of the interatomic dipole-dipole interaction strength and photon number on the atoms entanglement evolution are analyzed by means of numerical calculation.The results show that: The interatomic dipole-dipole interaction enhances entanglement between atoms,while photon number decreases entanglement between atoms.

We present an entanglement concentration protocol (ECP) for unknown less-entangled states resorting to the quantum-dot spins in double-sided optical microcavities.The protocol exploits an error-detected mechanism to overcome local computational errors,which is intrinsically robust to experimental imperfections and more practical than previous ECPs for QDs.We discuss the performance of the ECP with current experimental parameters,and the results show a success probability of 45％ for the present scheme without recycling can be achieved.The ECP could provide a promising building block for solid-state quantum repeaters and quantum networks in the future.

We study theoretically the Gaussian laser pump field and dump field conditions for producing ultracold cesium molecules from ultracold atomic condensates by the two-color photoassociation through the stimulated Raman adiabatic passage (STIRAP) in a tunneling four-level structure.An excited molecule |bk〉 is produced in an outer excited state from the ultracold atoms at the initial state |a〉 via the pump field.Then,the excited molecule |bk〉 is converted to the inner excited molecule |bv0〉by the tunneling coupling.Furthermore,the dump field drives |bv0〉 to the ground molecular state |g〉.In this progress,the detuning of pump field Δp is fixed at -(0.16 cm-1)32,and the detuning of dump field Δd is satisfied with the two-photon resonance condition,which can be obtained from the dark state solutions of the coupled mean-field equations.In the two-color photo association,we can control the two effective Rabi frequencies (Ω0p,Ω0d),the delay coefficient (α) and the width (T) of the two laser fields and obtain the high conversion efficiency (η≥0.9) as the optimum conditions of the pump and dump fields.In the meantime,the population dynamics of atoms and stable bound ground molecules with the conversion efficiency at 0.919 are investigated at specific parameters,where Ω0p=600×105 s-1、Ω0d=160×105 s-1、α=1.9、T=0.9×10-4 s.The unequal effective Rabi frequencies (Ω0p ≠Ω0d) are to the benefit of the coherent transfer from the atoms to the ground molecules through the STIRAP for the wide ranges of the delay coefficient and the width.Furthermore,we also investigate comparatively the cases of the small and large equal effective Rabi frequencies (Ω0p=Ω0d) for maintaining the delay coefficient and the width.The results have demonstrated that the conversion efficiencies are decreased sharply.Therefore,only the matched the effective Rabi frequencies,the delay coefficient and the width of the two laser fields can convert efficiently the ultracold atoms to the stable ground ultracold molecules.

After the study of vortex distribution of the Bose-Einstein condensates in a rotating harmonic plus Gaussian trap the virtual time evolution method,we get the effects of the rotational angular frequency and the interaction intensity between atoms on the vortex distribution,and corresponding effects on the distribution of quantized vortices,ghost vortices and hidden vortices in the condensate.In addition to the ordinary quantized and ghost vortices,the hidden vortices are distributed along the central barrier.When the interaction intensity is constant,the number of visible vortex and hidden vortex increases with the increase of rotation angular frequency.When the rotation angular frequency is constant,the number of visible vortices increases with the increase of the interaction intensity between atoms,but the number of hidden vortices does not change.We find that the Feynman rule can be satisfied only when visible and hidden vortices are both considered.

In this paper,a metal-insulator-metal (MIM) type surface plasmonic waveguide (SPW)supporting multiple Fano resonances is designed,which is composed of a bus MIM waveguide with a stub resonator coupled with concentric double ring resonator (CDRR).The influence of coupling distance,stub height,and ring radius on Fano resonance is investigated with the finite element method(FEM).At the same time,the physical mechanism of multiple Fano resonances is analyzed according to magnetic field distribution.In addition,by changing the refractive index of the medium filled in CDRR,the application of the designed structure in the field of refractive index sensor is investigated.The results show that the sensitivity is up to 1 400 nm／RIU,and the figure of merit (FOM) is larger than 1 380.Finally,the slow-light characteristics of the structure are investigated,and it is found that the maximum group refractive index in the vicinity of the Fano peak is about 11.4 and the maximum delay time is about 0.076 ps.The designed waveguide structure has potential applications in the fields of nanoscale filters,refractive index sensors,and slow light devices and so on.

In this paper,a metal-insulator-metal (MIM) surface plasmonic waveguide(SPW) structure based on concentric nanoring resonators is designed,of which the outer resonator is a perfect ring,and the inner one has a narrow slit.The numerical and analytical methods are used to investigate thetransmission characteristics under different structural parameters.It is found that when the split width is θ=5° and its rotation angle is φ=45°,a clear plasmonic induced absorption (PIA) effect is emerged at the wavelength of 674 nm.Based on this result,the application of the proposed waveguide structure in the area of refractive index sensor is studied at first.The result shows that the sensitivity is larger than 600 nm／RIU,and its maximum figure of merit (FOM) is about 700.Second,the characteristics of fast-and slow-light effects are studied,and it is shown that optical delay time of about -0.081 ps is occurred at the PIA transmission dip,which means the larger abnormal dispersion and fast-light effect.While optical delay time of about 0.045 ps and 0.043 ps occur at the two transmission peaks on both sides of the PIA dip,which means the larger normal dispersion and slow-light effect.This surface plasmonic optical waveguide structure has potential application prospects in the fields of nano refractive index sensors,nano filters,nano all-optical switches,and on-chip integrating of nano optical devices.