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Scalable photonic network architecture based on motional averaging in room temperature gas.

Borregaard J, Zugenmaier M, Petersen JM, Shen H, Vasilakis G, Jensen K, Polzik ES, Sørensen AS - Nat Commun (2016)

Bottom Line: Thermal atomic vapours, which present a simple and scalable resource, have only been used for continuous variable processing or for discrete variable processing on short timescales where atomic motion is negligible.Here we develop a theory based on motional averaging to enable room temperature discrete variable quantum memories and coherent single-photon sources.We demonstrate the feasibility of this approach to scalable quantum memories with a proof-of-principle experiment with room temperature atoms contained in microcells with spin-protecting coating, placed inside an optical cavity.

View Article: PubMed Central - PubMed

Affiliation: The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, Copenhagen Ø DK-2100, Denmark.

ABSTRACT
Quantum interfaces between photons and atomic ensembles have emerged as powerful tools for quantum technologies. Efficient storage and retrieval of single photons requires long-lived collective atomic states, which is typically achieved with immobilized atoms. Thermal atomic vapours, which present a simple and scalable resource, have only been used for continuous variable processing or for discrete variable processing on short timescales where atomic motion is negligible. Here we develop a theory based on motional averaging to enable room temperature discrete variable quantum memories and coherent single-photon sources. We demonstrate the feasibility of this approach to scalable quantum memories with a proof-of-principle experiment with room temperature atoms contained in microcells with spin-protecting coating, placed inside an optical cavity. The experimental conditions correspond to a few photons per pulse and a long coherence time of the forward scattered photons is demonstrated, which is the essential feature of the motional averaging.

No MeSH data available.


Related in: MedlinePlus

Atomic level structure and experimental setup.(a) All atoms are initially pumped to state /0〉. The transition /0〉→/e〉 is driven by a weak laser field (Ω), while the cavity mode (g) couples /e〉 and /1〉. The driving is far detuned  from the excited level to suppress the effects of Doppler broadening and absorption. γ is the decay rate of the excited level /e〉. (b) The atomic ensemble is kept in a small cell inside a single-sided cavity with a low finesse (cell cavity). The quantum photons (thin arrows) are coupled from the cell cavity into a high-finesse cavity (filter cavity), which separates them from the classical field (thick arrows) and averages over the atomic motion. Finally, the quantum photons are measured with a SPD. We associate the quantum field inside the cell cavity (filter cavity) with an annihilation operator , while the field at the detector is associated with the annihilation operator . SPD, single-photon detector.
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f1: Atomic level structure and experimental setup.(a) All atoms are initially pumped to state /0〉. The transition /0〉→/e〉 is driven by a weak laser field (Ω), while the cavity mode (g) couples /e〉 and /1〉. The driving is far detuned from the excited level to suppress the effects of Doppler broadening and absorption. γ is the decay rate of the excited level /e〉. (b) The atomic ensemble is kept in a small cell inside a single-sided cavity with a low finesse (cell cavity). The quantum photons (thin arrows) are coupled from the cell cavity into a high-finesse cavity (filter cavity), which separates them from the classical field (thick arrows) and averages over the atomic motion. Finally, the quantum photons are measured with a SPD. We associate the quantum field inside the cell cavity (filter cavity) with an annihilation operator , while the field at the detector is associated with the annihilation operator . SPD, single-photon detector.

Mentions: We consider a setup where an ensemble of atoms with a Λ-scheme level structure is kept in a small alkene-coated cell2627 (see Fig. 1). A cell with quadratic cross section with side length 2L=300 μm containing caesium atoms was used in ref. 28, for which the average time between atom–wall collisions was ∼1.4 μs and the coherence time was 10 ms. The atoms can thus endure several collisions with the walls before losing coherence making the cells suitable as quantum memories. The ensemble is kept at room temperature and, to enhance the interaction with the light, the cell is placed inside a single-sided optical cavity (‘cell' cavity). In the proof-of-principle experiment (see below) a finesse of has been set by the output mirror transmission of 20% and the reflection losses on the cell windows but a cavity with a higher finesse can easily be envisioned. The light leaving the cell cavity is coupled into another high-finesse cavity (‘filter' cavity), whose purpose is described below.


Scalable photonic network architecture based on motional averaging in room temperature gas.

Borregaard J, Zugenmaier M, Petersen JM, Shen H, Vasilakis G, Jensen K, Polzik ES, Sørensen AS - Nat Commun (2016)

Atomic level structure and experimental setup.(a) All atoms are initially pumped to state /0〉. The transition /0〉→/e〉 is driven by a weak laser field (Ω), while the cavity mode (g) couples /e〉 and /1〉. The driving is far detuned  from the excited level to suppress the effects of Doppler broadening and absorption. γ is the decay rate of the excited level /e〉. (b) The atomic ensemble is kept in a small cell inside a single-sided cavity with a low finesse (cell cavity). The quantum photons (thin arrows) are coupled from the cell cavity into a high-finesse cavity (filter cavity), which separates them from the classical field (thick arrows) and averages over the atomic motion. Finally, the quantum photons are measured with a SPD. We associate the quantum field inside the cell cavity (filter cavity) with an annihilation operator , while the field at the detector is associated with the annihilation operator . SPD, single-photon detector.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4834638&req=5

f1: Atomic level structure and experimental setup.(a) All atoms are initially pumped to state /0〉. The transition /0〉→/e〉 is driven by a weak laser field (Ω), while the cavity mode (g) couples /e〉 and /1〉. The driving is far detuned from the excited level to suppress the effects of Doppler broadening and absorption. γ is the decay rate of the excited level /e〉. (b) The atomic ensemble is kept in a small cell inside a single-sided cavity with a low finesse (cell cavity). The quantum photons (thin arrows) are coupled from the cell cavity into a high-finesse cavity (filter cavity), which separates them from the classical field (thick arrows) and averages over the atomic motion. Finally, the quantum photons are measured with a SPD. We associate the quantum field inside the cell cavity (filter cavity) with an annihilation operator , while the field at the detector is associated with the annihilation operator . SPD, single-photon detector.
Mentions: We consider a setup where an ensemble of atoms with a Λ-scheme level structure is kept in a small alkene-coated cell2627 (see Fig. 1). A cell with quadratic cross section with side length 2L=300 μm containing caesium atoms was used in ref. 28, for which the average time between atom–wall collisions was ∼1.4 μs and the coherence time was 10 ms. The atoms can thus endure several collisions with the walls before losing coherence making the cells suitable as quantum memories. The ensemble is kept at room temperature and, to enhance the interaction with the light, the cell is placed inside a single-sided optical cavity (‘cell' cavity). In the proof-of-principle experiment (see below) a finesse of has been set by the output mirror transmission of 20% and the reflection losses on the cell windows but a cavity with a higher finesse can easily be envisioned. The light leaving the cell cavity is coupled into another high-finesse cavity (‘filter' cavity), whose purpose is described below.

Bottom Line: Thermal atomic vapours, which present a simple and scalable resource, have only been used for continuous variable processing or for discrete variable processing on short timescales where atomic motion is negligible.Here we develop a theory based on motional averaging to enable room temperature discrete variable quantum memories and coherent single-photon sources.We demonstrate the feasibility of this approach to scalable quantum memories with a proof-of-principle experiment with room temperature atoms contained in microcells with spin-protecting coating, placed inside an optical cavity.

View Article: PubMed Central - PubMed

Affiliation: The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, Copenhagen Ø DK-2100, Denmark.

ABSTRACT
Quantum interfaces between photons and atomic ensembles have emerged as powerful tools for quantum technologies. Efficient storage and retrieval of single photons requires long-lived collective atomic states, which is typically achieved with immobilized atoms. Thermal atomic vapours, which present a simple and scalable resource, have only been used for continuous variable processing or for discrete variable processing on short timescales where atomic motion is negligible. Here we develop a theory based on motional averaging to enable room temperature discrete variable quantum memories and coherent single-photon sources. We demonstrate the feasibility of this approach to scalable quantum memories with a proof-of-principle experiment with room temperature atoms contained in microcells with spin-protecting coating, placed inside an optical cavity. The experimental conditions correspond to a few photons per pulse and a long coherence time of the forward scattered photons is demonstrated, which is the essential feature of the motional averaging.

No MeSH data available.


Related in: MedlinePlus