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Quantum Networking with Atomic Ensembles


Schematic of a quantum network [1].
Quantum networks are composed of quantum nodes that interact coherently through quantum channels [1]. For example, a quantum network can serve as
  •  a ‘web’ for connecting quantum processors for computation and communication, or
  • as a ‘simulator’ allowing investigations of quantum critical phenomena arising from interactions among the nodes mediated by the channels.
The physical realization of quantum networks generically requires dynamical systems capable of
  • generating and storing entangled states among multiple quantum memories,
  • and efficiently transferring stored entanglement into quantum channels for distribution across the network.
[1] H. J. Kimble, Nature 453, 1023-1030 (2008).

Our Interest

Picture of the two first nodes of
our elementary quantum network.
Photo by  Nara Cavalcanti

The collective effects of atomic ensembles provide another means to control the light-matter interface.

Our interest is to develop the physical resources that enable quantum repeaters, thereby allowing entanglement-based quantum communication tasks over quantum networks on distance scales much larger than set by the attenuation length of optical fibers, including quantum cryptography or quantum teleportation.

We worked with ensembles (1, 2 and even 4) of cooled cesium atoms in magneto-optical trap
s.  Non-classically correlated photon pairs with a programmable delay interval have been first generated and, additionally, used as a source of conditional single photons. For more information, please visit our previous homepage.

Recent Work

[2] "Entanglement of spin waves among four quantum memories"
K. S. Choi, A. Goban, S. B. Papp, S. J. van Enk, and H. J. Kimble, Nature 468, 412-416 (2010)

Caltech Press Release

The quadripartite atomic entanglement is generated for four collective atomic modes of the four ensembles. Images result from background-subtracted fluorescence of the four atomic ensembles [2].
Very recently, we demonstrated measurement-induced entanglement stored in four atomic memories; user-controlled, coherent transfer of the atomic entanglement to four photonic channels; and characterization of the full quadripartite entanglement using quantum uncertainty relations [2].

Click here to view the movie of the 3D rendering of the entanglement parameters for the dissipative dynamics of atomic entanglement.
[3] "A state-insensitive, compensated nanofiber trap" 
C. Lacroûte, K. S. Choi, A. Goban, D. J. Alton, D. Ding, N. P. Stern and H. J. Kimble, New J. Phys. 14 (2012) 023056.

[4] "Demonstration of a state-insensitive, compensated nanofiber trap"
A. Goban, K. S. Choi, D. J. Alton, D. Ding, C. Lacroûte, M. Pototschnig, T. Thiele, N. P. Stern and H. J. Kimble,

Simulation of Trapping Potential [3,4].
To go beyond four ensembles, we hope to explore a system for more scalable light-matter interface. The fiber-trapped atom array becomes a natural candidate.

Most recently, we have experimentally realized an optical trap that localizes single Cs atoms ~215 nm from surface of a dielectric nanofiber [3,4].

Team members:
    Principal Investigator:
        H. Jeff. Kimble, William L. Valentine Professor of Physics

        Martin Pototschnig, Chen-Lung Hung

    Graduate Students:
        Akihisa Goban, Ding Ding, Juan Muniz

        Kyung S. Choi, KAIST

    Collaborators on tapered-fiber fabrication
        Daniel J. Alton, Clement Lacroute, Pol Forn-Diaz, Andrew McClung

    Former Members:
        Kyung Soo Choi, KAIST
        Scott Papp, NIST Boulder
        Julien Luarat, ENS-LKB, Paris
        Hui Deng, University of Michigan
        Chin-Wen (James) Chou, NIST Boulder
        Daniel Felinto, University of Recife
        Sergey Polyakov, NIST Optical Technology Division
        Warwick Bowen, University of Otago
        Alex Kuzmich, Georgia Institute of Technology