Key Laboratory of Fundamental Physical Quantities Measurement of Ministry of Education

Wuhan, China

Key Laboratory of Fundamental Physical Quantities Measurement of Ministry of Education

Wuhan, China
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Liu S.,Huazhong University of Science and Technology | Liu S.,Hubei University of Arts and Science | Li J.,Huazhong University of Science and Technology | Li J.,Key Laboratory of Fundamental Physical Quantities Measurement of Ministry of Education | And 2 more authors.
Optics Express | Year: 2013

We investigate the entanglement generation between two nitrogen-vacancy (NV) centers in diamond nanocrystal coupled to a high-Q counterpropagating twin whispering-gallery modes (WGMs) of a microtoroidal resonator. For looking into the degree and dynamics of the entanglement, we calculate the concurrence using the microscopic master equation approach. The influences of the coupling strength between the WGMs (or the size of the two spherical NV centers), the distance between two NV centers, the frequency detuning between the NV center and microresonator, and the initial state of the system on the dynamics of concurrence are discussed in detail. It is found that the maximum entanglement between the two NV centers can be created by properly adjusting these controllable system parameters. Our results may provide further insight into future solid-state cavity quantum electrodynamics (CQED) system for quantum information engineering. © 2013 Optical Society of America.


He L.,Huazhong University of Science and Technology | Li Y.,Huazhong University of Science and Technology | Zhang Q.,Huazhong University of Science and Technology | Lu P.,Huazhong University of Science and Technology | Lu P.,Key Laboratory of Fundamental Physical Quantities Measurement of Ministry of Education
Optics Express | Year: 2013

We propose an efficient method to generate an ultra-broadband supercontinuum by using a three-color field synthesized by a 1600 nm driving pulse and two weak (3200 nm and 400 nm) control pulses. The results show that the acceleration and ionization steps in the HHG process are simultaneously controlled in our scheme, which can not only broaden the bandwidth but also enhance the harmonic yields of the generated spectrum. Thus a high-efficiency supercontinuum with the photon energies ranging from 205 eV to 480 eV is observed. Based on our 3D propagation simulations, we show that the short quantum path of the supercontinuum is well phase-matched and can be selected under suitable propagation conditions. Thereby, the modulation due to quantum path interference is largely reduced and intense isolated sub-100 as pulses with tunable central wavelengths are directly obtained within water window spectral region. © 2013 Optical Society of America.


Li Y.,Huazhong University of Science and Technology | Zhu X.,Huazhong University of Science and Technology | Zhang Q.,Huazhong University of Science and Technology | Qin M.,Huazhong University of Science and Technology | And 2 more authors.
Optics Express | Year: 2013

We perform a quantum-orbit analysis for the dependence of high-order-harmonic yield on the driving field ellipticity and the polarization properties of the generated high harmonics. The electron trajectories responsible for the emission of particular harmonics are identified. It is found that, in elliptically polarized driving field, the electrons have ellipticity-dependent initial velocities, which lead to the decrease of the ionization rate. Thus the harmonic yield steeply decreases with laser ellipticity. Besides, we show that the polarization properties of the harmonics are related to the complex momenta of the electron. The physical origin of the harmonic ellipticity is interpreted as the consequence of quantum-mechanical uncertainty of the electron momentum. Our results are verified with the experimental results as well as the numerical solutions of the time dependent Schrödinger equation from the literature. © 2013 Optical Society of America.


Liu K.,Huazhong University of Science and Technology | Zhang Q.,Huazhong University of Science and Technology | Zhang Q.,Key Laboratory of Fundamental Physical Quantities Measurement of Ministry of Education | Lan P.,Huazhong University of Science and Technology | And 3 more authors.
Optics Express | Year: 2013

We have theoretically studied the effect of nuclear mass on electron localization in dissociating H2+ and its isotopes subjected to a few-cycle 3-μm pulse. Our results reveal an anomalous isotopic effect in which the degree of electron-directed reactivity can be even higher for heavier isotopes in the intense midinfrared field. We show, for the first time, the pronounced electron localization can be established through the interferences among the multi-photon coupling channels. Due to the relative enhancement of higher-order coupling channels with growing mass, the interference maxima at different kinetic energy of the spectra gradually become in phase, ultimately resulting in the larger dissociation asymmetries of heavier isotopes. © 2013 Optical Society of America.


Huang C.,Huazhong University of Science and Technology | Zhou Y.,Huazhong University of Science and Technology | Zhang Q.,Huazhong University of Science and Technology | Zhang Q.,Key Laboratory of Fundamental Physical Quantities Measurement of Ministry of Education | And 2 more authors.
Optics Express | Year: 2013

With the three-dimensional classical ensemble model, we investigate the correlated electron emission in nonsequential double ion-ization (NSDI) of argon atoms by few-cycle laser pulses. Our calculations well reproduce the experimentally observed cross-shaped structure in the correlated two-electron momentum spectrum [Nature Commun. 3, 813 (2012)]. By tracing these NSDI trajectories, we find that besides the process of recollision-induced excitation with subsequent ionization just before the next field maximum, the recollision ionization also significantly contributes to the cross-shaped structure. © 2013 Optical Society of America.


Liu W.,Huazhong University of Science and Technology | Wang K.,Huazhong University of Science and Technology | Wang K.,Key Laboratory of Fundamental Physical Quantities Measurement of Ministry of Education | Liu Z.,Huazhong University of Science and Technology | And 3 more authors.
Nano Letters | Year: 2013

We report a direct observation on the laterally emitted surface second harmonic generation (SHG) in a single ZnTe nanowire. The highly directional surface SHG radiates vertically to the nanowire growth-axis with a high conversion efficiency of 5 × 10-6 and a low divergence angle of 4. Polarization state, emission intensity, and direction of the surface SHG are found to be dependent on the polarization of the pumping laser, which is further confirmed by numerical simulations. The laterally emitted surface SHG with a high efficiency and low divergence angle has great potential for short-wavelength nanolasers, nonlinear microscopic imaging, and polarization-dependent photonic integrating. © 2013 American Chemical Society.


Zhou Y.,Huazhong University of Science and Technology | Huang C.,Huazhong University of Science and Technology | Liao Q.,Huazhong University of Science and Technology | Lu P.,Huazhong University of Science and Technology | Lu P.,Key Laboratory of Fundamental Physical Quantities Measurement of Ministry of Education
Physical Review Letters | Year: 2012

With a classical ensemble model that includes electron correlations during the whole ionization process, we investigate strong-field sequential double ionization of Ar by elliptically polarized pulses at the quantitative level. The experimentally observed intensity-dependent three-band or four-band structures in the ion momentum distributions are well reproduced with this classical model. More importantly, the experimentally measured ionization time of the second electrons by A.N. Pfeiffer et al., which cannot be predicted by the standard independent-electron model, is quantitatively reproduced by this fully classical correlated model. The success of our work encourages classical descriptions and interpretations of the complex multielectron effects in strong-field ionization where nonperturbative quantum approaches are currently not feasible. © 2012 American Physical Society.


Zhang D.,Wuhan Polytechnic University | Yu R.,Wuhan Institute of Technology | Li J.,Huazhong University of Science and Technology | Li J.,Key Laboratory of Fundamental Physical Quantities Measurement of Ministry of Education | And 2 more authors.
Optics Communications | Year: 2014

A scheme of two-dimensional atom localization is proposed based on the phase-sensitive probe absorption and gain in a four-level atomic system with a closed-loop configuration. Due to the spatially dependent atom-field interaction, the position probability distribution of the atom can be directly determined by measuring the resulting absorption and gain spectra of the weak probe laser field. It is found that the phase-sensitive property of the atomic system significantly improves the localization behavior. Especially the maximal probability of finding the atom at a particular position within the sub-wavelength domain of the standing waves can arrive at unity by appropriate choice of the system parameters. © 2014 Elsevier B.V.


Zhou Y.,Huazhong University of Science and Technology | Huang C.,Huazhong University of Science and Technology | Lu P.,Huazhong University of Science and Technology | Lu P.,Key Laboratory of Fundamental Physical Quantities Measurement of Ministry of Education
Optics Express | Year: 2012

We theoretically investigated sequential double ionization (SDI) of Ar by the nearly circularly polarized laser pulses with a fully correlated classical ensemble model. The ion momentum distributions of our numerical results at various laser intensities and pulse durations agree well with the experimental results. The experimentally observed multi-electron effects embodied in the joint momentum spectrum of the two electrons is also reproduced by our correlated classical calculations. Interestingly, our calculations show that the angular distribution of the first photoelectron from the trajectories which eventually suffer SDI differs from the distribution of the photoelectrons from above-threshold ionization trajectories. This observation provides additional evidence of multi-electron effects in strong field SDI. © 2012 Optical Society of America.


Li J.,Huazhong University of Science and Technology | Li J.,Key Laboratory of Fundamental Physical Quantities Measurement of Ministry of Education | Yu R.,Wuhan Institute of Technology | Ding C.,Henan University | And 2 more authors.
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2014

Optical-frequency combs consisting of equally spaced sharp lines in frequency space have triggered substantial advances in optical-frequency metrology and precision measurements and in applications such as laser-based gas sensing and molecular fingerprinting. Here, we propose a scheme to generate a type of optical-frequency combs and convert them from one cavity to the other in a hybrid optical system composed of a pair of coupled photonic crystal cavities called a photonic molecule (PM) and a single semiconductor quantum dot (QD) embedded in one cavity of the molecule. Optical-frequency combs are formed by the interaction between a cavity mode and a continuous-wave (CW) two-tone driving laser consisting of a pump field and a seed field via QD-induced strong nonlinearity. In this situation, the initial input pump and seed CW lasers can interact among each other and produce optical higher-order sidebands with equal spacing via parametric frequency conversion provided by QD-induced nonlinear optical effects. Using numerical simulations, it is clearly shown that the beat frequency of the two-tone components plays an important role in determining the comb spacing and matched frequency combs can be formed in the PM. We also demonstrate that the present interacting QD-PM system can serve as a platform to generate large-scale quantum entanglement between two comb modes. The results obtained here may be useful for real experiments in a photonic crystal platform. © 2014 American Physical Society.

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