We investigate the generation and the evolution of continuous-variable(CV) entanglement from a laserdriven four-state atom inside a doubly resonant cavity under Raman excitation.Two transitions in the four-state atom ...We investigate the generation and the evolution of continuous-variable(CV) entanglement from a laserdriven four-state atom inside a doubly resonant cavity under Raman excitation.Two transitions in the four-state atom independently interact with the two cavity modes,while two other transitions are driven by coupling laser fields.By including the atomic relaxation as well as cavity losses,we show that the CV entanglement with large mean number of photons can be generated in our scheme.We also show that the intensity of the coupling laser fields can influence effectively the entanglement period of the cavity field.Different from the conventional resonant excitation scheme where zero one-photon detuning are required,it is found that the intensity and period of entanglement between the two cavity modes as well as the total mean photon number of the cavity field can be adjusted by properly modulating the frequency detuning.展开更多
We report Raman lasing and the optical analog of electromagnetically-induced-transparency(EIT) in a whispering-gallery-mode(WGM) microtoroid resonator embedded in a low refractive index polymer matrix together with a ...We report Raman lasing and the optical analog of electromagnetically-induced-transparency(EIT) in a whispering-gallery-mode(WGM) microtoroid resonator embedded in a low refractive index polymer matrix together with a tapered fiber coupler. The microtoroid resonator supports both single mode and multimode Raman lasing with low power thresholds. Observations of Fano and EIT-like phenomena in a packaged microresonator will enable high resolution sensors and can be used in networks where slow-light effect is needed. These results will open up new possibilities for portable, robust, and stable WGM microlasers and resonator-based sensors for applications in various environments.展开更多
In this work, we report the electrical field tuning of magneto-phonon resonance in monolayer graphene under magnetic fields up to 9 T. It is found that the carrier concentration can drastically affect the G （E2g） ph...In this work, we report the electrical field tuning of magneto-phonon resonance in monolayer graphene under magnetic fields up to 9 T. It is found that the carrier concentration can drastically affect the G （E2g） phonon response to a varying magnetic field through a pronounced magneto-phonon resonance （MPR）. In charge neutral or slightly doped monolayer graphene, both the energy and the line width of the E2g phonon show clear variation with magnetic fields. This is attributed to magneto-phonon resonance between magnetoexcitations and the E2g phonons. In contrast, when the Fermi level of the monolayer graphene is far away from the Dirac point, the G band shows weak magnetic dependence and exhibits a symmetric line-shape. This suggests that the magneto-phonon coupling around 4 T has been switched off due to the Pauli blocking of the inter-Landau level excitations. Moreover, the G band asymmetry caused by Fano resonance between excitonic many-body states and the E2g phonons is observed. This work offers a way to study the magnetoexcitation phonon interaction of materials through magneto-Raman spectroscopy with an external electrical field.展开更多
基金Supported by National Natural Science Foundation of China under Grant Nos.10704017,11074036 and 10874050National Fundamental Research Program of China Grant No.2007CB936300
文摘We investigate the generation and the evolution of continuous-variable(CV) entanglement from a laserdriven four-state atom inside a doubly resonant cavity under Raman excitation.Two transitions in the four-state atom independently interact with the two cavity modes,while two other transitions are driven by coupling laser fields.By including the atomic relaxation as well as cavity losses,we show that the CV entanglement with large mean number of photons can be generated in our scheme.We also show that the intensity of the coupling laser fields can influence effectively the entanglement period of the cavity field.Different from the conventional resonant excitation scheme where zero one-photon detuning are required,it is found that the intensity and period of entanglement between the two cavity modes as well as the total mean photon number of the cavity field can be adjusted by properly modulating the frequency detuning.
基金supported by the US Army Research Office(ARO)(W911NF-12-1-0026 and W911NF1710189)
文摘We report Raman lasing and the optical analog of electromagnetically-induced-transparency(EIT) in a whispering-gallery-mode(WGM) microtoroid resonator embedded in a low refractive index polymer matrix together with a tapered fiber coupler. The microtoroid resonator supports both single mode and multimode Raman lasing with low power thresholds. Observations of Fano and EIT-like phenomena in a packaged microresonator will enable high resolution sensors and can be used in networks where slow-light effect is needed. These results will open up new possibilities for portable, robust, and stable WGM microlasers and resonator-based sensors for applications in various environments.
文摘In this work, we report the electrical field tuning of magneto-phonon resonance in monolayer graphene under magnetic fields up to 9 T. It is found that the carrier concentration can drastically affect the G （E2g） phonon response to a varying magnetic field through a pronounced magneto-phonon resonance （MPR）. In charge neutral or slightly doped monolayer graphene, both the energy and the line width of the E2g phonon show clear variation with magnetic fields. This is attributed to magneto-phonon resonance between magnetoexcitations and the E2g phonons. In contrast, when the Fermi level of the monolayer graphene is far away from the Dirac point, the G band shows weak magnetic dependence and exhibits a symmetric line-shape. This suggests that the magneto-phonon coupling around 4 T has been switched off due to the Pauli blocking of the inter-Landau level excitations. Moreover, the G band asymmetry caused by Fano resonance between excitonic many-body states and the E2g phonons is observed. This work offers a way to study the magnetoexcitation phonon interaction of materials through magneto-Raman spectroscopy with an external electrical field.
