Current Research at NIST
Solid-State, Ensemble-Based Quantum Repeater
Rare-earth ion-doped crystals are promising candidates for use as a quantum memory for photon states due to the long ground-state coherence times of the ionic ensembles. Recent experiments using Pr3+ doped Y2SiO5 (Pr:Y2SiO5) have demonstrated decoherence times of tens of seconds [PRL 92, 077601 (2004), PRL 95, 030506 (2005)], and storage and retrieval of classical optical pulses using electromagnetically induced transparency (EIT) with storage times up to
10 s [PRL 95, 063601 (2005)]. We are interested in the practical aspects of using Pr:Y2SiO5 as a quantum memory for photon states, with a special interest in optimization for use in specific quantum-repeater protocols, such as the Duan-Lukin-Cirac-Zoller (DLCZ) scheme [Nature 414, 413 (2001)]. Experiments are currently under way.
Selected publications
1. M. D. Eisaman, S. Polyakov, M. Hohensee, J. Fan, P. Hemmer, and A. Migdall, Optimizing the storage and retrieval efficiency of a solid-state quantum memory through tailored state preparation, Proc. of SPIE 6780, 67800K (2007).
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Microstructure-fiber-based source of entangled photon pairs
Despite the rapid progress over the last decade toward practical applications of quantum communication, many challenges remain. In particular, for real-world quantum communication and cryptography applications to take advantage of entanglement, we need a robust source of entangled photon pairs with high spectral brightness, broad wavelength coverage, and a single-mode spatial output that is compatible with fiber networks or free-space operation. Until recently, polarization-entangled photon-pair sources for such applications have been implemented almost exclusively using spontaneous parametric down-conversion in materials exhibiting chi-2 optical nonlinearities. Because these conditions can be met over a wide range of parameters, photons are emitted into a large number of spatial and spectral modes, resulting in large collection losses when coupling into a single-mode optical fiber.
Recently, interest has shifted to materials exhibiting a third-order optical nonlinearity (chi-3) , which allows, for example, spontaneous four-wave mixing (SFWM) to occur in single-mode optical fibers. The advantage of a fiber-based source is obvious: polarization-entangled photon pairs can be created, selected, encoded, and delivered all within a single-mode fiber network with minimal losses.
My research in the laboratory of Dr. Alan Migdall at the National Institute of Standards and Technology (NIST) in Gaithersburg, MD involves work on the development of a polarization-entangled photon-pair source, based on a polarization-configured fiber Sagnac interferometer. Operating at room temperature and bi-directionally pumping this Sagnac interferometer with a total average pump power of 300 microwatts, we measured a two-photon coincidence rate of 7 kHz for 0.5 THz (0.9 nm) bandwidth. Using this source, we have created all four Bell states, and violated Bell’s inequality in the Clauser-Horne-Shimony-Holt by more than 22 standard deviations for each of the four Bell states.
The wavelength of the polarization-entangled two-photon state produced by our source can be chosen anywhere in a 21 nm range. To characterize the purity of the states produced by this source, we used quantum-state tomography to reconstruct the corresponding density matrices, with fidelities of 95% or more for each Bell state.
Selected publications
3. M. D. Eisaman, E. A. Goldschmidt, J. Chen, J. Fan, and A. Migdall, Experimental test of nonlocal realism using a fiber-based source of polarization-entangled photon pairs, Phys. Rev. A 77, 032339 (2008).
- NIST Tech Beat article (link)
2. J. Fan, M. D. Eisaman, and A. Migdall, Quantum state tomography of a fiber-based source of polarization-entangled photon pairs, Optics Express 15, 18339 - 18344 (2007).
1. J. Fan, M. D. Eisaman, and A. Migdall, Bright phase-stable broadband fiber-based source of polarization-entangled photon pairs, Phys. Rev. A 76, 043836 (2007).
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Previous (Ph.D.) Research at Harvard
Generation, storage, and retrieval of nonclassical states of light using atomic ensembles
One of the most exciting challenges in quantum optics is the development of
techniques to facilitate controlled, coherent interactions between single photons and matter. Beyond their fundamental importance in optical science, such techniques provide the key elements for the practical realization of a photonic quantum network- an interconnected web of stationary sites capable of storing and processing quantum information. Such networks are expected to play a major role in extending the range of quantum communication and quantum cryptography to long distances, and possibly for implementing scalable quantum-information processors. A commonly envisioned realization of a quantum network involves single-photon transmission through optical fibers connecting a number of memory nodes that utilize atoms for the generation, storage and processing of quantum states. The realization of this vision requires: techniques for generating nonclassical states of light and atoms, techniques for coherent transfer of quantum states from photons to atoms and vice versa, and a quantum memory that is capable of storing, manipulating, and releasing quantum states at the level of individual quanta.
My Ph.D. work in the laboratory of Prof. Mikhail D. Lukin in the Physics Department at Harvard University used Electromagnetically Induced Transparency (EIT) in room-temperature rubidium-87 ensembles to realize a narrow-bandwidth source of nonclassical light, a memory that preserves the nonclassical statistics of this light, and a primitive quantum network comprised of two atomic-ensemble quantum memories connected by nonclassical light in an optical fiber.
Selected publications
4. M. D. Eisaman, Generation, storage, and Retrieval of Nonclassical States of Light using Atomic Ensembles, Department of Physics, Harvard University (2006).
3. M. D. Eisaman, A. André, F. Massou, M. Fleischhauer, A. S. Zibrov, and M. D. Lukin, Electromagnetically induced transparency with tunable single-photon pulses, Nature 438, 837-841 (2005).
- News and Views (pdf)
2. M. D. Eisaman, L. Childress, A. André, F. Massou, A. S. Zibrov, and M. D. Lukin, Shaping Quantum Pulses of Light via Coherent Atomic Memory, Phys. Rev. Lett. 93, 233602 (2004).
1. C. H. van der Wal, M. D. Eisaman, A. André, R. L. Walsworth, D. F. Phillips, A. S. Zibrov, and M. D. Lukin, Atomic Memory for Correlated Photon States, Science 301, 196 (2003).
- Supplementary Information (pdf)
- Perspectives (pdf)