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Research Today

K. Tikhonov (PostDoc)
Prof. T.Yu. Golubeva
Prof. Yu.M. Golubev

We discuss the influence of atomic thermal motion on the efficiency of multimode quantum memory in two configurations: over the free expand of atoms cooled beforehand in a magneto-optical trap, and over complete mixing of atoms in a closed cell at room temperature. We consider the high-speed quantum memory, and assume that writing and retrieval are short enough, and the dis- placements of atoms during these stages are negligibly small. At the

same time we take in account thermal motion during the storage time, which, as well known, must be much longer than durations of all the other memory processes for successful application of memory cell in communication and computation. We will analyze this influence in terms of eigenmodes of the full memory cycle and show that distortion of the eigenmodes, caused by thermal motion, leads to the efficiency reduction. We will demonstrate, that in the multimode memory this interconnection has complicated character.

 

K. Tikhonov, T. Golubeva, Yu. Golubev "High-speed quantum memory with thermal motion of atoms",  arXiv:1502.07509v1

A. Vetlugin (PostDoc)
Prof. I.V. Sokolov

We investigate theoretically addressable spatially multimode (parallel) quantum memory applications in Quantum Information. For write-in stage we achieve the decrease of the output field and as it should be the increase of the write-in efficiency due to making the conditions of the destructive interference on the input mirror. With a view to reach this type of interference we research time-reversal and impedance-matching approaches. The first one gives the best efficiency for short pulses, but the second one allows one to organize the memory-cells communication. For the read-out process we examine the addressability, i.e. the ability to

read-out the desired spatial mode in required direction and/or the desired pulse from the sequence in required order.

 

А.Н. Ветлугин, И.В. Соколов "Эффективность параллельной квантовой памяти в резонаторной конфигурации", Оптика и спектроскопия 115 (6), 114 (2013).

A.N. Vetlugin and I.V. Sokolov "Addressable parallel cavity-based quantum memory", Eur. Phys. J. D 68, 269 (2014).

A. Losev (PostDoc)
Prof. Yu.M. Golubev
As. Prof. T.Yu. Golubeva

We investigate a resonant broadband memory in an atomic ensemble consisting of tripod-type atoms.The ensemble interaction with three laser fields, one quantum (signal) and two classical (drivers) field. We consider a high-speed broadband multimode quantum memory in a resonance approach. In a procedure "writing" we map state of the signal field onto spin atomic collective coherences 2-1 and 2-3. We investigate statistical properties of these coherences, such as their entanglement.

Also using the same method we research the statistics property of the atomic ensemble consisting from several sub-ensembles of different kind of atoms. Here all atoms are lambda-type. A signal field transition is the same for all atoms. Transitions of driving fields are different.