Information storage and retrieval by stopping pulses of light

Susanna Orlic

R. Bullough, H. M. Gibbs

Despite the importance of quantum interference and coherent population trapping to the theory of electromagnetically induced transparency (EIT), it is shown that the recent experiments which slow down and even stop a light pulse in a dielectric really rely on a linear, refractive index type theory. From this point of view and in considerable contrast, the experiment on degenerate self-induced transparency (SIT) done 27 years ago which slowed down an optical pulse (in principle to zero velocity) was based on an intrinsically nonlinear (soliton type) theory. In quantum mechanical terms both theories are developed at the level of expectation values only and at this level the two different theories come together in terms of the storage and retrieval of information. In the Appendix we analyse the nature of this information in terms of the quantum equations governing linear EIT and nonlinear SIT.

Theodore D. Holstein, S. K. Lyo, R. Orbach

Ian S. Osborne

Physics Photons are ideal carriers of information. They are fast and coherent, and because they don't interact much with each other they can have very long lifetimes. However, stopping, processing, and manipulating the photons requires them to be stored in a memory, where doing so can damage their fragile quantum properties, which leads to a loss of coherence. Although photons have been coherently stored in and retrieved from ensembles of atom gases, both warm and cold atom clouds, for practical applications a solid-state memory would be desired. Heinze et al. have developed a method to enhance the storage time of photons in a rare-earth–ion—doped crystal. They use a series of laser pulses to initialize the crystal for photon storage and then load it with their “information photons.” By iteratively optimizing the experimental parameters, they show that they can store light pulses and even entire images in the crystal and then retrieve them up to a minute later with their coherent properties intact. The results present an important step toward building a viable quantum network. Phys. Rev. Lett. 111 , 033601(2013).

James K. Thompson, Adam T. Black, Vladan Vuletić

Darrick E. Chang, Amir H. Safavi‐Naeini, Mohammad Hafezi +2 more

The ability to coherently store and retrieve optical information in a rapidly tunable manner is an important ingredient for all‐optical information processing. In the classical domain, this optical buffering is necessary to manage information flow in complex networks. In quantum information processing, such a system can also serve as a long‐term memory capable of storing the full quantum information contained in an optical pulse. Here we suggest a novel approach to light storage involving an optical waveguide coupled to an optomechanical crystal array, where light in the waveguide can be dynamically and reversibly mapped into long‐lived mechanical vibrations in the array. This technique enables large bandwidths and long storage and delay times in a compact, on‐chip platform.