Slow and stored light and optical depth

Creation of two-photon states via interactions between Rydberg atoms during light storage

We propose a new method to create two-photon states in a controllable way using interaction between the Rydberg atoms during the storage and retrieval of slow light. A distinctive feature of the suggested procedure is that the slow light is stored into a superposition of two atomic coherences under conditions of electromagnetically induced transparency (EIT). Interaction between the atoms during the storage period creates entangled pairs of atoms in a superposition state that is orthogonal to the initially stored state. Restoring the slow light from this new atomic state one can produce a two …

Coherent propagation of a single photon in a lossless medium: $0π$ pulse formation, slow photon, storage and retrieval in multiple temporal modes

Single-photon coherent optics represents a fundamental importance for the investigation of quantum light-matter interactions. While most work has considered the interaction in the steady-state regime, here we demonstrate that a single-photon pulse shorter than any relaxation time in a medium propagates without energy loss and is consistently transformed into a zero-area pulse. A general analytical solution is found for photon passage through a cold ensemble of $Λ$-type atoms confined inside a hollow core of a single-mode photonic-crystal fiber. We use the robust far off-resonant Raman scheme t…

Stationary light in atomic media

When ensembles of atoms interact with coherent light fields a great many interesting and useful effects can be observed. In particular, the group velocity of the coherent fields can be modified dramatically. Electromagnetically induced transparency is perhaps the best known example, giving rise to very slow light. Careful tuning of the optical fields can also produce stored light where a light field is mapped completely into a coherence of the atomic ensemble. In contrast to stored light, in which the optical field is extinguished, stationary light is a bright field of light with a group veloc…

Slow and fast light behavior of single photons from a quantum dot interacting with the excited state hyperfine structure of the Cesium D1-line

Hybrid interfaces between distinct quantum systems play a major role in the implementation of quantum networks. Quantum states have to be stored in memories to synchronize the photon arrival times for entanglement swapping by projective measurements in quantum repeaters or for entanglement purification. Here, we analyze the distortion of a single photon wave packet propagating through a dispersive and absorptive medium with high spectral resolution. Single photons are generated from a single In(Ga)As quantum dot with its excitonic transition precisely set relative to the Cesium D1 transition. …

Experimental superradiance and slow light effects for quantum memories

The effects of high optical depth phenomena, such as superradiance, are investigated in potential quantum memory materials. The results may have relevance for several schemes, including CRIB, AFC and EIT-based quantum memories, which are based on using ensembles as storage media. It is shown that strong superradiant effects, manifested as decay rates larger than 1/T2*, are present even for moderate values of alphaL < 5, and increases as a function of alphaL. For even higher alphaL, effects like off-resonant slow light is demonstrated and discussed, and finally, the efficiency of time-reversed …

Experimental demonstration of spinor slow light

Slow light based on the effect of electromagnetically induced transparency is of great interest due to its applications in low-light-level nonlinear optics and quantum information manipulation. The previous experiments all dealt with the single-component slow light. Here we report the experimental demonstration of two-component or spinor slow light using a double tripod atom-light coupling scheme. The scheme involves three atomic ground states coupled to two excited states by six light fields. The oscillation due to the interaction between the two components was observed. Based on the stored l…

Transfer and storage of vortex states in light and matter waves

We theoretically explore the transfer of vortex states between atomic Bose-Einstein condensates and optical pulses using ultra-slow and stopped light techniques. We find shining a coupling laser on a rotating two-component ground state condensate with a vortex lattice generates a probe laser field with optical vortices. We also find that optical vortex states can be robustly stored in the atomic superfluids for long times (>100 ms).

Coherent Control of Stationary Light Pulses

We present a detailed analysis of the recently demonstrated technique to generate quasi-stationary pulses of light [M. Bajcsy {\it et al.}, Nature (London) \textbf{426}, 638 (2003)] based on electromagnetically induced transparency. We show that the use of counter-propagating control fields to retrieve a light pulse, previously stored in a collective atomic Raman excitation, leads to quasi-stationary light field that undergoes a slow diffusive spread. The underlying physics of this process is identified as pulse matching of probe and control fields. We then show that spatially modulated contro…

Optical vortices of slow light using tripod scheme

We consider propagation, storing and retrieval of slow light (probe beam) in a resonant atomic medium illuminated by two control laser beams of larger intensity. The probe and two control beams act on atoms in a tripod configuration of the light-matter coupling. The first control beam is allowed to have an orbital angular momentum (OAM). Application of the second vortex-free control laser ensures the adiabatic (lossles) propagation of the probe beam at the vortex core where the intensity of the first control laser goes to zero. Storing and release of the probe beam is accomplished by switching…

过阻尼RLC电路中的制备控制弛豫：通向谱姆彭巴效应的教学路径

Preparation-controlled relaxation in an overdamped RLC circuit: A pedagogical route to the spectral Mpemba effect

本文通过过阻尼RLC电路展示谱姆彭巴效应，证明初始能量并非决定弛豫路径的唯一因素，并推广至随机、开放及量子系统，揭示制备模态与观测模式对弛豫反转的关键作用。

Storing and processing optical information with ultra-slow light in Bose-Einstein condensates

We theoretically explore coherent information transfer between ultra-slow light pulses and Bose-Einstein condensates (BECs) and find that storing light pulses in BECs, by switching off the coupling field, allows the coherent condensate dynamics to process optical information. We develop a formalism, applicable in both the weak and strong probe regimes, to analyze such experiments and establish several new results. Investigating examples relevant to Rb-87 experimental parameters we see a variety of novel two-component BEC dynamics occur during the storage, including interference fringes, gentle…

Effect of Injected Noise on Electromagnetically Induced Transparency and Slow Light

We have examined theoretically the phenomenon of Electromagnetically Induced Transparency (EIT) in a three-level system operating in the lambda-configuration in presence of an externally injected noise coupling the ground level to the intermediate (metastable) level. The changes in the depth and the width of the induced transparency and the slowing down of the probe light have been calculated as function of the probe detuning and the strength of the injected noise. The calculations are within the rotating-wave approximation (RWA). Our main results are the reduction and the broadening of the EI…

Demonstration of a memory for tightly guided light in an optical nanofiber

We report the experimental observation of slow-light and coherent storage in a setting where light is tightly confined in the transverse directions. By interfacing a tapered optical nanofiber with a cold atomic ensemble, electromagnetically induced transparency is observed and light pulses at the single-photon level are stored in and retrieved from the atomic medium with an overall efficiency of (10 +/- 0.5) %. Collapses and revivals can be additionally controlled by an applied magnetic field. Our results based on subdiffraction-limited optical mode interacting with atoms via the strong evanes…