arXiv subjects

Szu-Cheng Cheng

Publications and source records attributed to Szu-Cheng Cheng.

21 records · Page 2Linked to original sources

arXiv2008

Collective Excitations of Rotating Dipolar Fermi Gases in the Fractional Quantum Hall Regime

We apply the magneto-roton theory of the fractional quantum Hall effect to study the collective excitation spectrum of rotating dipolar Fermi gases. The predicted spectrum has a finite energy gap in the long wavelength limit and a roton minimum at finite wave vector. The roton minimum being deepened from filling factor 1/3 to filling factor 1/5 is a signature of incipient crystallization near filling factor 1/7. We also demonstrate that there are no low-lying single-particle excitations below the roton mode. The fractional-quantum-Hall fluid rotating dipolar fermions behaves as an incompressible superfluid at low temperature.

cond-mat.mes-hall↗

arXiv2008

Fractional phenomena of the spontaneous emission of a two-level atom in photonic crystals

We suggest a better mathematical method, fractional calculus, for studying the behavior of the atom-field interaction in photonic crystals. By studying the spontaneous emission of an atom in a photonic crystal with one-band isotropic model, we found that the long-time inducing memory of the spontaneous emission is a fractional phenomenon. This behavior could be well described by the fractional calculus. And the results show no steady photon-atom bound state for the atomic resonant transition frequency lying in the proximity of allowed band edge which is encountered in the previous study [J. Opt. B: Quantum Semiclass. Opt. {\bf 5}, R43 (2003)]. The correctness of this result is validated by the ``cut-off smoothing'' density of photon states (DOS) with fractional calculus. By obtaining a rigorous solution without the multiple-valued problem for the system, we show the method of fractional calculus has logically concise property.

cond-mat.mtrl-sci↗

arXiv2008

Coherent control of spontaneous emission of a three-level atom in a coherent photonic band gap reservoir

By studying the fluorescence and optical properties of a three-level system, we propose a new point of view on the coherent control of these spectra. With the definite phase difference between the fields of the air band and dielectric band in photonic band gap (PBG) reservoirs, the spectra of spontaneous emission, absorption, and dispersion exhibit the coherent property and quantum interference effect. This coherent interference depending on the position of the embedded atom and the width of band gap causes the coupling of the free-space light and the PBG light to result in blue shift of spectra and the appearance of dark lines and kinks. By coherently controlling the position-dependent dispersion, we can tune the frequency of slow light.

cond-mat.mtrl-sci↗