Optical storage with electromagnetically induced transparency in a dense cold atomic ensemble

Zhang, Shanchao; Zhou, Shuyu; Loy, M. M. T.; Wong, George K.; Du, Shengwang

doi:10.1364/ol.36.004530

Cited by 61 publications

(30 citation statements)

References 23 publications

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“…By optimizing for higher atom number and therefore higher OD, high efficiency is also possible in cold atom systems, although this can come at the expense of long storage time due to higher temperatures. A memory efficiency of 50% was achieved using a two-dimensional (2D) magneto-optical trap (MOT) of 85 Rb with an OD < 140, and a coherence time of a few hundred nanoseconds [26]. Similar efficiencies were achieved for single-photon storage in a 87 Rb BEC in a cross-beam dipole trap containing 1.2 × 10 6 atoms [27].…”

Section: Introductionmentioning

confidence: 84%

Gradient echo memory in an ultra-high optical depth cold atomic ensemble

et al. 2013

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Quantum memories are an integral component of quantum repeaters-devices that will allow the extension of quantum key distribution to communication ranges beyond that permissible by passive transmission. A quantum memory for this application needs to be highly efficient and have coherence times approaching a millisecond. Here we report on work towards this goal, with the development of a 87 Rb magneto-optical trap with a peak optical depth of 1000 for the D2 F = 2 → F = 3 transition using spatial and temporal dark spots. With this purpose-built cold atomic ensemble we implemented the gradient echo memory (GEM) scheme on the D1 line. Our data shows a memory efficiency of 80 ± 2% and coherence times up to 195 µs, which is a factor of four greater than previous GEM experiments implemented in warm vapour cells.

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Section: Introductionmentioning

confidence: 84%

Gradient echo memory in an ultra-high optical depth cold atomic ensemble

et al. 2013

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“…One can also understand this as a storage process: the photon quantum state is converted into the atomic state which is reemitted back to the photon in the same optical mode at a later time. This quantum storage process is induced by the single-photon self interference, which is different from the quantum memories based on electromagnetically induced transparency [18][19][20].…”

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confidence: 98%

Coherent Control of Single-Photon Absorption and Reemission in a Two-Level Atomic Ensemble

et al. 2012

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We demonstrate coherent control of single-photon absorption and reemission in a two-level cold atomic ensemble. This is achieved by interfering the incident single-photon wave packet with the emission (or scattering) wave. For a photon with an exponential growth waveform with a time constant equal to the excited-state lifetime, we observe that the single-photon emission probability during the absorption can be suppressed due to the perfect destructive interference. After the incident photon waveform is switched off, the absorbed photon is then reemitted to the same spatial mode as that of the incident photon with an efficiency of 20%. For a photon with an exponential decay waveform with the same time constant, both the absorption and reemission occur within the waveform duration. Our experimental results suggest that the absorption and emission of a single photon in a two-level atomic ensemble may possibly be manipulated by shaping its waveform in the time domain. DOI: 10.1103/PhysRevLett.109.263601 PACS numbers: 42.50.Nn, 03.65.Ta, 32.80.Qk, 42.50.Ct Photon absorption and emission are two key probes to study the light-matter quantum interaction, which lays down the foundations for atomic, molecular, and optical physics [1][2][3]. When a coherent optical pulse propagates through a medium, the absorption and emission can coherently modify its spectral components and lead to many interesting and important optical phenomena, such as attenuation, amplification, distortion, and slow and fast light effects [4][5][6][7][8]. For a single photon, causality requires that the absorption and reemission follow the right time order: the reemission can only occur following the absorption. Although this quantum time order has been observed as the antibunching effect in resonance fluorescence measured by two-photon correlations [9,10], it is not controllable on demand in these experiments. When a single photon enters a two-level atomic medium, the absorption and emission usually both occur within the photon pulse duration. Recently, Scully et al. proposed a scheme for observing directed ''spontaneous'' emission excited by a single photon [11].In this Letter, we demonstrate coherent control of singlephoton absorption and reemission in a two-level cold atomic ensemble in free space by shaping the singlephoton waveform. Making use of the destructive interference between the emission (or scattering) and the incident photon wave packet, we show that the probability of reemitting the photon during the absorption can be completely suppressed when the incident photon has an exponential growth waveform with a time constant equal to the excitedstate lifetime. The reemission process only starts after the incident photon waveform is switched off and thus can be controlled on demand. This technique can be used to efficiently excite atoms with a given single atom. Our result may have potential applications in the quantum networks that require efficient conversion between flying single-photon states and local atomic states [12]. Figure 1 i...

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“…[57][58][59] Most recently, We use the dark-line 2D MOT with a high optical depth to study EIT optical storage. 60 Our 2D MOT at a high optical depth with a low trapping laser power provides a nearly ideal cold atom source for EITrelated quantum optics research and may find important applications in atomic-ensemble-based quantum networks.…”

Section: Discussionmentioning

confidence: 99%

“…[57][58][59] Most recently, the 2D MOT with dark line was applied for efficient optical storage. 60 Our 2D MOT with tunable OD will find important application in atomic-ensemble-based quantum communication and quantum information processing.…”

Section: Introductionmentioning

confidence: 99%

A dark-line two-dimensional magneto-optical trap of 85Rb atoms with high optical depth

Zhang¹,

Chen²,

Liu³

et al. 2012

Review of Scientific Instruments

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We describe the apparatus of a dark-line two-dimensional (2D) magneto-optical trap (MOT) of 85Rb cold atoms with high optical depth (OD). Different from the conventional configuration, two (of three) pairs of trapping laser beams in our 2D MOT setup do not follow the symmetry axes of the quadrupole magnetic field: they are aligned with 45° angles to the longitudinal axis. Two orthogonal repumping laser beams have a dark-line volume in the longitudinal axis at their cross over. With a total trapping laser power of 40 mW and repumping laser power of 18 mW, we obtain an atomic OD up to 160 in an electromagnetically induced transparency (EIT) scheme, which corresponds to an atomic-density-length product NL = 2.05 × 1015 m−2. In a closed two-state system, the OD can become as large as more than 600. Our 2D MOT configuration allows full optical access of the atoms in its longitudinal direction without interfering with the trapping and repumping laser beams spatially. Moreover, the zero magnetic field along the longitudinal axis allows the cold atoms maintain a long ground-state coherence time without switching off the MOT magnetic field, which makes it possible to operate the MOT at a high repetition rate and a high duty cycle. Our 2D MOT is ideal for atomic-ensemble-based quantum optics applications, such as EIT, entangled photon pair generation, optical quantum memory, and quantum information processing.

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Optical storage with electromagnetically induced transparency in a dense cold atomic ensemble

Cited by 61 publications

References 23 publications

Gradient echo memory in an ultra-high optical depth cold atomic ensemble

Gradient echo memory in an ultra-high optical depth cold atomic ensemble

Coherent Control of Single-Photon Absorption and Reemission in a Two-Level Atomic Ensemble

A dark-line two-dimensional magneto-optical trap of 85Rb atoms with high optical depth

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