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Deterministically Entangling Two Remote Atomic Ensembles via Light-Atom Mixed Entanglement Swapping.

Liu Y, Yan Z, Jia X, Xie C - Sci Rep (2016)

Bottom Line: Here we propose a scheme of deterministically entangling two remote atomic ensembles via continuous-variable entanglement swapping between two independent quantum systems involving light and atoms.Each of two stationary atomic ensembles placed at two remote nodes in a quantum network is prepared to a mixed entangled state of light and atoms respectively.Then, the entanglement swapping is unconditionally implemented between the two prepared quantum systems by means of the balanced homodyne detection of light and the feedback of the measured results.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan, 030006, People's Republic of China.

ABSTRACT
Entanglement of two distant macroscopic objects is a key element for implementing large-scale quantum networks consisting of quantum channels and quantum nodes. Entanglement swapping can entangle two spatially separated quantum systems without direct interaction. Here we propose a scheme of deterministically entangling two remote atomic ensembles via continuous-variable entanglement swapping between two independent quantum systems involving light and atoms. Each of two stationary atomic ensembles placed at two remote nodes in a quantum network is prepared to a mixed entangled state of light and atoms respectively. Then, the entanglement swapping is unconditionally implemented between the two prepared quantum systems by means of the balanced homodyne detection of light and the feedback of the measured results. Finally, the established entanglement between two macroscopic atomic ensembles is verified by the inseparability criterion of correlation variances between two anti-Stokes optical beams respectively coming from the two atomic ensembles.

No MeSH data available.


Functions of the correlation variances on the detuning of light and atoms interaction.Trace (i), (ii) and (iii) correspond the correlation variances on the detuning of light and atoms interaction when ΩW = 5 MHz, 6 MHz and 7 MHz, respectively. Trace (iv) represents QNL.
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f5: Functions of the correlation variances on the detuning of light and atoms interaction.Trace (i), (ii) and (iii) correspond the correlation variances on the detuning of light and atoms interaction when ΩW = 5 MHz, 6 MHz and 7 MHz, respectively. Trace (iv) represents QNL.

Mentions: The function of the correlation variances versus the detuning Δ is illustrated in Fig. 5, when is taken. The trace (i) to (iii) correspond to the Rabi frequency ΩW = 5 MHz, 6 MHz and 7 MHz, respectively, and trace (iv) is QNL. For a given detuning Δ, the correlation variances decrease when the Rabi frequency of the write optical pulse ΩW increase. From Fig. 5, we can see that the atom-atom entanglement reaches the best value for zero detuning in ideal condition. However, in the real experiment the harmful extra noise increased, which will reduce the entanglement, if the detuning is too small, and thus the scheme has to work at a certain detuning3437. The numerical calculation show that −4.3 dB entanglement between two atomic ensembles is obtained in a 700 MHz detuning via light-atom mixed entanglement swapping, which is better than the result of the optical entanglement swapping7. To avoid the huge extra noise at the atomic resonance the detuning has been applied in many experimental systems of quantum optics, such as, Appel J. et al.34 illustrate that 630 MHz is the optimal detuning for quantum memory of squeezed light in Rb atomic ensemble by means of EIT approach34; Qin Z.Z. et al.37 demonstrate that 800 MHz detuning is the best choice, and −7 dB intensity-difference squeezing in Rb atomic ensemble based on four-wave mixing is experimentally generated37. Thus in the systems of light-atom interaction we have to take an appropriate compromising between high efficiency and large noise by using a certain detuning.


Deterministically Entangling Two Remote Atomic Ensembles via Light-Atom Mixed Entanglement Swapping.

Liu Y, Yan Z, Jia X, Xie C - Sci Rep (2016)

Functions of the correlation variances on the detuning of light and atoms interaction.Trace (i), (ii) and (iii) correspond the correlation variances on the detuning of light and atoms interaction when ΩW = 5 MHz, 6 MHz and 7 MHz, respectively. Trace (iv) represents QNL.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4863164&req=5

f5: Functions of the correlation variances on the detuning of light and atoms interaction.Trace (i), (ii) and (iii) correspond the correlation variances on the detuning of light and atoms interaction when ΩW = 5 MHz, 6 MHz and 7 MHz, respectively. Trace (iv) represents QNL.
Mentions: The function of the correlation variances versus the detuning Δ is illustrated in Fig. 5, when is taken. The trace (i) to (iii) correspond to the Rabi frequency ΩW = 5 MHz, 6 MHz and 7 MHz, respectively, and trace (iv) is QNL. For a given detuning Δ, the correlation variances decrease when the Rabi frequency of the write optical pulse ΩW increase. From Fig. 5, we can see that the atom-atom entanglement reaches the best value for zero detuning in ideal condition. However, in the real experiment the harmful extra noise increased, which will reduce the entanglement, if the detuning is too small, and thus the scheme has to work at a certain detuning3437. The numerical calculation show that −4.3 dB entanglement between two atomic ensembles is obtained in a 700 MHz detuning via light-atom mixed entanglement swapping, which is better than the result of the optical entanglement swapping7. To avoid the huge extra noise at the atomic resonance the detuning has been applied in many experimental systems of quantum optics, such as, Appel J. et al.34 illustrate that 630 MHz is the optimal detuning for quantum memory of squeezed light in Rb atomic ensemble by means of EIT approach34; Qin Z.Z. et al.37 demonstrate that 800 MHz detuning is the best choice, and −7 dB intensity-difference squeezing in Rb atomic ensemble based on four-wave mixing is experimentally generated37. Thus in the systems of light-atom interaction we have to take an appropriate compromising between high efficiency and large noise by using a certain detuning.

Bottom Line: Here we propose a scheme of deterministically entangling two remote atomic ensembles via continuous-variable entanglement swapping between two independent quantum systems involving light and atoms.Each of two stationary atomic ensembles placed at two remote nodes in a quantum network is prepared to a mixed entangled state of light and atoms respectively.Then, the entanglement swapping is unconditionally implemented between the two prepared quantum systems by means of the balanced homodyne detection of light and the feedback of the measured results.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan, 030006, People's Republic of China.

ABSTRACT
Entanglement of two distant macroscopic objects is a key element for implementing large-scale quantum networks consisting of quantum channels and quantum nodes. Entanglement swapping can entangle two spatially separated quantum systems without direct interaction. Here we propose a scheme of deterministically entangling two remote atomic ensembles via continuous-variable entanglement swapping between two independent quantum systems involving light and atoms. Each of two stationary atomic ensembles placed at two remote nodes in a quantum network is prepared to a mixed entangled state of light and atoms respectively. Then, the entanglement swapping is unconditionally implemented between the two prepared quantum systems by means of the balanced homodyne detection of light and the feedback of the measured results. Finally, the established entanglement between two macroscopic atomic ensembles is verified by the inseparability criterion of correlation variances between two anti-Stokes optical beams respectively coming from the two atomic ensembles.

No MeSH data available.