Coherent optical pulse sequencer for quantum applications

10 Sep 2009

Mr. Mahdi Hosseini and colleagues in the atom-light entanglement team at the Australian National University report in the journal Nature a quantum memory system that could improve encryption or act as random access memory in a quantum computer.

The bandwidth and versatility of optical devices have revolutionized information technology systems and communication networks. Precise and arbitrary control of an optical field that preserves optical coherence is an important requisite for many proposed photonic technologies. For quantum information applications, a device that allows storage and on-demand retrieval of arbitrary quantum states of light would form an ideal quantum optical memory. Recently, significant progress has been made in implementing atomic quantum memories using electromagnetically induced transparency, photon echo spectroscopy, off-resonance Raman spectroscopy and other atom–light interaction processes. Single-photon and bright-optical-field storage with quantum states have both been successfully demonstrated.

The ANU team present a coherent optical memory based on photon echoes induced through controlled reversible inhomogeneous broadening. Our scheme allows storage of multiple pulses of light within a chosen frequency bandwidth, and stored pulses can be recalled in arbitrary order with any chosen delay between each recalled pulse. Furthermore, pulses can be time-compressed, time-stretched or split into multiple smaller pulses and recalled in several pieces at chosen times. Although their experimental results are so far limited to classical light pulses, the technique should enable the construction of an optical random-access memory for time-bin quantum information, and have potential applications in quantum information processing.

For more information see

• http://www.abc.net.au/science/
• http://photonics.anu.edu.au/qoptics/index.html#

Full Article
Coherent optical pulse sequencer for quantum applications.
Mahdi Hosseini, Ben M. Sparkes, Gabriel Hétet, Jevon J. Longdell, Ping Koy Lam & Ben C. Buchler,
Nature 461, 241 (2009)