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A universal quantum information processor for scalable quantum communication and networks.

Yang X, Xue B, Zhang J, Zhu S - Sci Rep (2014)

Bottom Line: Here, we present a theoretical proposal to efficiently and conveniently achieve a universal quantum information processor (QIP) via atomic coherence in an atomic ensemble.By employing EIT-based nondegenerate four-wave mixing processes, the generation, exchange, distribution, and manipulation of light-light, atom-light, and atom-atom multipartite entanglement can be efficiently and flexibly achieved in a deterministic way with only coherent light fields.This method greatly facilitates the operations in quantum information processing, and holds promising applications in realistic scalable quantum communication and quantum networks.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Shanghai University, Shanghai 200444, China.

ABSTRACT
Entanglement provides an essential resource for quantum computation, quantum communication, and quantum networks. How to conveniently and efficiently realize the generation, distribution, storage, retrieval, and control of multipartite entanglement is the basic requirement for realistic quantum information processing. Here, we present a theoretical proposal to efficiently and conveniently achieve a universal quantum information processor (QIP) via atomic coherence in an atomic ensemble. The atomic coherence, produced through electromagnetically induced transparency (EIT) in the Λ-type configuration, acts as the QIP and has full functions of quantum beam splitter, quantum frequency converter, quantum entangler, and quantum repeater. By employing EIT-based nondegenerate four-wave mixing processes, the generation, exchange, distribution, and manipulation of light-light, atom-light, and atom-atom multipartite entanglement can be efficiently and flexibly achieved in a deterministic way with only coherent light fields. This method greatly facilitates the operations in quantum information processing, and holds promising applications in realistic scalable quantum communication and quantum networks.

No MeSH data available.


(a) The triple-Λ-type system of the D1 transitions in 85Rb atom coupled by the coupling (Ec), probe (Ep), and mixing (Em1 and Em2) fields based on the experimental configuration used in Ref. [28], where Ep and Ec fields both resonantly drive /2〉–/3〉 and /1〉–/3〉 transitions, and the corresponding Stokes fields E1, and anti-Stokes fields E2 are generated through two FWM processes. (b) The equivalent configuration of (a) with the two lower states driven by the atomic coherence σ12 precreated by the strong on-resonant Ec and Ep fields in the Λ-type EIT configuration.
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f1: (a) The triple-Λ-type system of the D1 transitions in 85Rb atom coupled by the coupling (Ec), probe (Ep), and mixing (Em1 and Em2) fields based on the experimental configuration used in Ref. [28], where Ep and Ec fields both resonantly drive /2〉–/3〉 and /1〉–/3〉 transitions, and the corresponding Stokes fields E1, and anti-Stokes fields E2 are generated through two FWM processes. (b) The equivalent configuration of (a) with the two lower states driven by the atomic coherence σ12 precreated by the strong on-resonant Ec and Ep fields in the Λ-type EIT configuration.

Mentions: The considered model, as shown in Fig. 1a, is based on the experimental configuration in Ref. [28], where the relevant energy levels and applied/generated laser fields form a triple-Λ-type system. Levels /1〉, /2〉, and /3〉 correspond, respectively, to the ground-state hyperfine levels 5S1/2 (F = 3), 5S1/2 (F = 2), and the excited state 5P1/2 in D1 line of 85Rb atom with the ground-state hyperfine splitting of 3.036 GHz. The probe field Ep (with frequency ωp and Rabi frequency Ωp) and coupling field Ec (with frequency ωc and Rabi frequency Ωc) are relatively strong and tuned to resonance with the transitions /2〉–/3〉 and /1〉–/3〉, respectively. By applying a third mixing field Em1 (or Em2) with frequency ωm1 (or ωm2), off-resonantly coupling levels /2〉 (or /1〉) and /3〉 with detuning Δ1 = ωm1 − ω32 (or Δ2 = ωm2 − ω31), a Stokes field E1 (or an anti-Stokes field E2) can be created through the nondegenerate FWM process. In fact, as shown in Fig. 1b, the produced Stokes field E1 (or anti-Stokes field E2) can be equivalently regarded as scattering the field Em1 (or Em2) off the atomic coherence σ12 pre-established by the strong coupling and probe fields in the Λ-type EIT configuration formed by levels /1〉, /2〉, and /3〉. In Refs. [18,19,20], we have employed the similar scheme to generate arbitrary number of nondegenerate narrow-band entangled fields and create quantum entangler via the pre-established atomic spin wave, however, the quantum properties of the scattering fields as well as the entangled feature between the scattering fields and the generated fields have not been investigated. In fact, as shown in Ref. [28], correlations and anti-correlations between the scattering and generated fields have been experimentally observed via atomic spin coherence in 85Rb atomic system. In what follows, by using the Heisenberg-Langevin method with the scattering fields and the generated Stokes/anti-Stokes fields treated quantum mechanically, we show how the atomic coherence can act as a QIP and can be used to realize the exchange and distribution of multipartite entangled state.


A universal quantum information processor for scalable quantum communication and networks.

Yang X, Xue B, Zhang J, Zhu S - Sci Rep (2014)

(a) The triple-Λ-type system of the D1 transitions in 85Rb atom coupled by the coupling (Ec), probe (Ep), and mixing (Em1 and Em2) fields based on the experimental configuration used in Ref. [28], where Ep and Ec fields both resonantly drive /2〉–/3〉 and /1〉–/3〉 transitions, and the corresponding Stokes fields E1, and anti-Stokes fields E2 are generated through two FWM processes. (b) The equivalent configuration of (a) with the two lower states driven by the atomic coherence σ12 precreated by the strong on-resonant Ec and Ep fields in the Λ-type EIT configuration.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4197420&req=5

f1: (a) The triple-Λ-type system of the D1 transitions in 85Rb atom coupled by the coupling (Ec), probe (Ep), and mixing (Em1 and Em2) fields based on the experimental configuration used in Ref. [28], where Ep and Ec fields both resonantly drive /2〉–/3〉 and /1〉–/3〉 transitions, and the corresponding Stokes fields E1, and anti-Stokes fields E2 are generated through two FWM processes. (b) The equivalent configuration of (a) with the two lower states driven by the atomic coherence σ12 precreated by the strong on-resonant Ec and Ep fields in the Λ-type EIT configuration.
Mentions: The considered model, as shown in Fig. 1a, is based on the experimental configuration in Ref. [28], where the relevant energy levels and applied/generated laser fields form a triple-Λ-type system. Levels /1〉, /2〉, and /3〉 correspond, respectively, to the ground-state hyperfine levels 5S1/2 (F = 3), 5S1/2 (F = 2), and the excited state 5P1/2 in D1 line of 85Rb atom with the ground-state hyperfine splitting of 3.036 GHz. The probe field Ep (with frequency ωp and Rabi frequency Ωp) and coupling field Ec (with frequency ωc and Rabi frequency Ωc) are relatively strong and tuned to resonance with the transitions /2〉–/3〉 and /1〉–/3〉, respectively. By applying a third mixing field Em1 (or Em2) with frequency ωm1 (or ωm2), off-resonantly coupling levels /2〉 (or /1〉) and /3〉 with detuning Δ1 = ωm1 − ω32 (or Δ2 = ωm2 − ω31), a Stokes field E1 (or an anti-Stokes field E2) can be created through the nondegenerate FWM process. In fact, as shown in Fig. 1b, the produced Stokes field E1 (or anti-Stokes field E2) can be equivalently regarded as scattering the field Em1 (or Em2) off the atomic coherence σ12 pre-established by the strong coupling and probe fields in the Λ-type EIT configuration formed by levels /1〉, /2〉, and /3〉. In Refs. [18,19,20], we have employed the similar scheme to generate arbitrary number of nondegenerate narrow-band entangled fields and create quantum entangler via the pre-established atomic spin wave, however, the quantum properties of the scattering fields as well as the entangled feature between the scattering fields and the generated fields have not been investigated. In fact, as shown in Ref. [28], correlations and anti-correlations between the scattering and generated fields have been experimentally observed via atomic spin coherence in 85Rb atomic system. In what follows, by using the Heisenberg-Langevin method with the scattering fields and the generated Stokes/anti-Stokes fields treated quantum mechanically, we show how the atomic coherence can act as a QIP and can be used to realize the exchange and distribution of multipartite entangled state.

Bottom Line: Here, we present a theoretical proposal to efficiently and conveniently achieve a universal quantum information processor (QIP) via atomic coherence in an atomic ensemble.By employing EIT-based nondegenerate four-wave mixing processes, the generation, exchange, distribution, and manipulation of light-light, atom-light, and atom-atom multipartite entanglement can be efficiently and flexibly achieved in a deterministic way with only coherent light fields.This method greatly facilitates the operations in quantum information processing, and holds promising applications in realistic scalable quantum communication and quantum networks.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Shanghai University, Shanghai 200444, China.

ABSTRACT
Entanglement provides an essential resource for quantum computation, quantum communication, and quantum networks. How to conveniently and efficiently realize the generation, distribution, storage, retrieval, and control of multipartite entanglement is the basic requirement for realistic quantum information processing. Here, we present a theoretical proposal to efficiently and conveniently achieve a universal quantum information processor (QIP) via atomic coherence in an atomic ensemble. The atomic coherence, produced through electromagnetically induced transparency (EIT) in the Λ-type configuration, acts as the QIP and has full functions of quantum beam splitter, quantum frequency converter, quantum entangler, and quantum repeater. By employing EIT-based nondegenerate four-wave mixing processes, the generation, exchange, distribution, and manipulation of light-light, atom-light, and atom-atom multipartite entanglement can be efficiently and flexibly achieved in a deterministic way with only coherent light fields. This method greatly facilitates the operations in quantum information processing, and holds promising applications in realistic scalable quantum communication and quantum networks.

No MeSH data available.