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Search Results: 1 - 10 of 516844 matches for " Ite A. Yu "
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Observation of Single-Photon Switching
Yong-Fan Chen,Zen-Hsiang Tsai,Yu-Chen Liu,Ite A. Yu
Physics , 2005,
Abstract: We report an experimental demonstration of single-photon switching in laser-cooled $^{87}$Rb atoms. A resonant probe pulse with an energy per unit area of one photon per $\lambda^2/2\pi$ propagates through the optically thick atoms. Its energy transmittance is greater than 63% or loss is less than $e^{-1}$ due to the effect of electromagnetically induced transparency. In the presence of a switching pulse with an energy per unit area of 1.4 photons per $\lambda^2/2\pi$, the energy transmittance of the same probe pulse becomes less than 37% or $e^{-1}$. This substantial reduction of the probe transmittance caused by single switching photons has potential applications in single-photon-level nonlinear optics and the manipulation of quantum information.
An effective thermal-parametrization theory for the slow-light dynamics in a Doppler-broadened electomagnetically induced transparency medium
Shih-Wei Su,Yi-Hsin Chen,Shih-Chuan Gou,Ite A. Yu
Physics , 2011, DOI: 10.1088/0953-4075/44/16/165504
Abstract: We model the effects of atomic thermal motion on the propagation of a light pulse in an electromagnetically induced transparency medium by introducing a set of effectively temperature-dependent parameters, including the Rabi frequency of the coupling field, optical density and relaxation rate of the ground state coherence, into the governing equations. The validity of this effective theory is verified by the close agreement between the theoretical results and the experimental data.
Electromagnetic induced transparency and slow light in interacting quantum degenerate atomic gases
H. H. Jen,Bo Xiong,Ite A. Yu,Daw-Wei Wang
Physics , 2012, DOI: 10.1364/JOSAB.30.002855
Abstract: We systematically develop the full quantum theory for the electromagnetic induced transparency (EIT) and slow light properties in ultracold Bose and Fermi gases. It shows a very different property from the classical theory which assumes frozen atomic motion. For example, the speed of light inside the atomic gases can be changed dramatically near the Bose-Einstein condensation temperature, while the presence of the Fermi sea can destroy the EIT effect even at zero temperature. From experimental point of view, such quantum EIT property is mostly manifested in the counter-propagating excitation schemes in either the low-lying Rydberg transition with a narrow line width or in the D2 transitions with a very weak coupling field. We further investigate the interaction effects on the EIT for a weakly interacting Bose-Einstein condensate, showing an inhomogeneous broadening of the EIT profile and nontrivial change of the light speed due to the quantum many-body effects beyond mean field energy shifts.
Hiding Single Photons With Spread Spectrum Technology
Chinmay Belthangady,Chih-Sung Chuu,Ite A. Yu,G. Y. Yin,J. M. Kahn,S. E. Harris
Physics , 2010, DOI: 10.1103/PhysRevLett.104.223601
Abstract: We describe a proof-of-principal experiment demonstrating the use of spread spectrum technology at the single photon level. We show how single photons with a prescribed temporal shape, in the presence of interfering noise, may be hidden and recovered.
Phase-dependent double-Λ electromagnetically induced transparency
Yi-Hsin Chen,Pin-Ju Tsai,Ite A. Yu,Ying-Cheng Chen,Yong-Fan Chen
Physics , 2014,
Abstract: We theoretically investigate a double-{\Lambda} electromagnetically induced transparency (EIT) system. The property of the double-{\Lambda} medium with a closed-loop configuration depends on the relative phase of the applied laser fields. This phase-dependent mechanism differentiates the double-{\Lambda} medium from the conventional Kerr-based nonlinear medium, e.g., EIT-based nonlinear medium discussed by Harris and Hau [Phys. Rev. Lett. 82, 4611 (1999)], which depends only on the intensities of the applied laser fields. Steady-state analytical solutions for the phase-dependent system are obtained by solving the Maxwell-Bloch equations. In addition, we discuss efficient all-optical phase modulation and coherent light amplification based on the proposed double-{\Lambda} EIT scheme.
Dynamics of slow light and light storage in a Doppler-broadened electromagnetically-induced-transparency medium: A numerical approach
Shih-Wei Su,Yi-Hsin Chen,Shih-Chuan Gou,Tzyy-Leng Horng,Ite A. Yu
Physics , 2011, DOI: 10.1103/PhysRevA.83.013827
Abstract: We present a numerical scheme to study the dynamics of slow light and light storage in an electromagneticallyinduced- transparency (EIT) medium at finite temperatures. Allowing for the motional coupling, we derive a set of coupled Schr\"{o}dinger equations describing a boosted closed three-level EIT system according to the principle of Galilean relativity. The dynamics of a uniformly moving EIT medium can thus be determined by numerically integrating the coupled Schr\"odinger equations for atoms plus one ancillary Maxwell-Schr\"odinger equation for the probe pulse. The central idea of this work rests on the assumption that the loss of ground-state coherence at finite temperatures can be ascribed to the incoherent superposition of density matrices representing the EIT systems with various velocities. Close agreements are demonstrated in comparing the numerical results with the experimental data for both slow light and light storage. In particular, the distinct characters featuring the decay of ground-state coherence can be well verified for slow light and light storage. This warrants that the current scheme can be applied to determine the decaying profile of the ground-state coherence as well as the temperature of the EIT medium.
Radiation trapping inside a hollow-core photonic crystal fiber
H. H. Jen,Chang-Yi Wang,Kevin C. J. Lee,Yi-Hsin Chen,Ite A. Yu
Physics , 2014,
Abstract: We report the radiation trapping effect inside a hollow-core photonic crystal fiber (PCF). An optical dipole trap was used to load and confine the atoms in the PCF without contacting the wall of the fiber. The transmission of a probe light propagating through the PCF was studied experimentally and theoretically. With the experimental results and theoretical predictions, we conclude that the radiation trapping can play a significant role and should be taken into account in the spectroscopic measurements inside the PCF.
Few-Photon All-Optical π Phase modulation Based on a Double-Λ System
Yen-Chun Chen,Hao-Chung Chen,Hsiang-Yu Lo,Bing-Ru Tsai,Ite A. Yu,Ying-Cheng Chen,Yong-Fan Chen
Physics , 2013,
Abstract: We propose an efficient all-optical phase modulation based on a double-{\Lambda} system and demonstrate a {\pi} phase shift of a few-photon pulse induced by another few-photon pulse in cold rubidium atoms with this scheme. By changing the phases of the applied laser fields, one can control the property of the double-{\Lambda} medium. This phase-dependent mechanism makes the double-{\Lambda} system different form the conventional cross-Kerr-based system which only depends on the applied laser intensities. The proposed scheme provides a new route to generate strong nonlinear interactions between photons, and may have potential for applications in quantum information technologies.
Stationary Light Pulses without Bragg Gratings
Yen-Wei Lin,Hung-Chih Chou,Thorsten Peters,Wen-Te Liao,Hung-Wen Cho,Pei-Chen Guan,Ite A. Yu
Physics , 2008, DOI: 10.1103/PhysRevLett.102.213601
Abstract: The underlying mechanism of the stationary light pulse (SLP) was identified as a band gap being created by a Bragg grating formed by two counter-propagating coupling fields of similar wavelength. Here we present a more general view of the formation of SLPs, namely several balanced four-wave mixing processes sharing the same ground-state coherence. Utilizing this new concept we report the first experimental observation of a bichromatic SLP at wavelengths for which no Bragg grating can be established. We also demonstrate the production of a SLP directly from a propagating light pulse without prior storage. Being easily controlled externally makes SLPs a very versatile tool for low-light-level nonlinear optics and quantum information manipulation.
Stationary Light Pulses in Cold Atomic Media
Wen-Te Liao,Yen-Wei Lin,Thorsten Peters,Hung-Chih Chou,Jian-Siung Wang,Pei-Chen Kuan,Ite A. Yu
Physics , 2008, DOI: 10.1103/PhysRevLett.102.213601
Abstract: Stationary light pulses (SLPs), i.e., light pulses without motion, are formed via the retrieval of stored probe pulses with two counter-propagating coupling fields. We show that there exist non-negligible hybrid Raman excitations in media of cold atoms that prohibit the SLP formation. We experimentally demonstrate a method to suppress these Raman excitations and realize SLPs in laser-cooled atoms. Our work opens the way to SLP studies in cold as well as in stationary atoms and provides a new avenue to low-light-level nonlinear optics.
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