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We present schemes for deterministically generating multi-qubit electron-spin entangled cluster states by the giant circular birefringence, induced by the interface between the spin of a photon and the spin of an electron confined in a quantum dot embedded in a double-sided microcavity. Based on this interface, we construct the controlled phase flip (CPF) gate deterministically which is performed on electron-spin qubits and is the essential component of the cluster-state generation. As one of the universal gates, the CPF gate constructed can also be utilized in achieving scalable quantum computing. Besides, we propose the entanglement concentration protocol to reconstruct a partially entangled cluster state into a maximally entangled one, resorting to the projection measurement on an ancillary photon. By iterating the concentration scheme several times, the maximum success probability can be achieved. The fidelities and experimental feasibilities are analyzed with respect to currently available techniques, indicating that our schemes can work well in both the strong and weak (Purcell) coupling regimes.

We study the pump-probe response in an optomechanical cavity accommodating an ensemble of two-level atoms interacting with a cavity mode, which is pumped by a strong driving field and probed by a weak signal field. The atomic excitation is examined without taking any approximations and may be in any regimes ranging from the low limit to the high limit for a given collective coupling constant between the atomic ensemble and the cavity mode. This then results in different absorption and dispersion spectra (such as optomechanically induced transparency, Fano-resonance, normal-mode splitting) when the excitation transfer from cavity mode to atomic ensemble is controlled to change from ineffective to effective. This indicates that a hybrid optomechanical response is indeed determined by the excitation of the atomic ensemble embedded in the optomechanical cavity. It is also of interest that the output signal component and the inside atomic polarization show either synchronous or asynchronous behaviors depending on how the atom-field detuning is chosen, i.e. equal to the mechanical resonator frequency or its negative. Such features may open up an effective avenue in coherently manipulating the internal atomic polarization via the external signal field, and vice versa.

Raman spectra of acetone's carbonyl stretching in 16 solvents were measured, and were also calculated by self-consistent reaction field (SCRF) method in Gaussian03. The frequency shift in experiment was analyzed by donor-acceptor model, Kirkwood model and SCRF model respectively. Among them, the donor-acceptor model can explain the shift very well. The SCRF method can do it also, while not as well as the donor-acceptor model, but is better than Kirkwood model. Correlating the mechanisms of the 3 methods, it was found that the donor-acceptor model is powerful in explaining the vibrational spectra of molecular bond, which is nucleophilic reagent. The SCRF model considers not only the influence of dielectric constant epsilon, but also the influence of the bulk and the structure of molecule etc. Although the model is complex and difficult to calculate, but it takes many factors into account, so the calculated results accord with experiment better than the Kirkwood model. The main parameter of the Kirkwood model is epsilon, so it is very simple and easy to calculate, nonetheless the trend of frequency shift can still be reflected, indicating that the dielectric constant epsilon is a main character affecting the frequency shift.

The visible absorption spectra of p-benzoquinone (PBQ) in CS2 were measured, and a weak absorption band around 507 nm attributed to n-pi* singlet-triplet transition was denonstrated. Using the resonance Raman effect excited in liquid-core optical fiber which can enhance Raman intensity by 6-9 orders of magnitude, the authors obtained the 514.5 nm excited resonance Raman (RR) spectra of PBQ at 1439 cn(-1) in the concentration range from 10(-3) to 10(-6) mol x L(-1). The new characteristic RR band is attributed to the symmetric C==O stretch (v(C==O)) of n-pi* singlet-triplet transition of PBQ. The resonance Raman shift is blue-shifted with decreasing concentration. The results of this paper are helpful for understanding the relationship between the electric structure and the photophysical properties of PBQ, and for obtaining more abundant structural information of molecules.