Soliton-Guided Quantum Information Processing

R. Bullough, Miki Wadati

Navin Khaneja, Steffen J. Glaser

Experiments in coherent spectroscopy correspond to control of quantum mechanical ensembles guiding them from initial to final target states by unitary transformations. The control inputs (pulse sequences) that accomplish these unitary transformations should take as little time as possible so as to minimize the effects of relaxation and to optimize the sensitivity of the experiments. Here, we present a radically different and generally applicable approach to efficient control of dynamics in spin chains of arbitrary length. The approach relies on the creation of localized spin waves, ``spin solitons'', and efficient propagation of these soliton states through the spin chain. The methods presented are expected to find immediate applications in control of spin dynamics in coherent spectroscopy and quantum information processing.

Gilles Brassard A

Andrzej Janutka

In a concept of simulating the quantum logic with vector solitons by the author (Janutka 2006 J. Phys. A: Math. Gen. 39 12505 ), the soliton polarization is thought of as a state vector of a system of cebits (classical counterparts of qubits) switched via collisions with other solitons. The advantage of this method of information processing compared to schemes using linear optics is the possibility of the determination of the information-register state in a single measurement. Minimization of the information-processing error for different optical realizations of the logical systems is studied in the framework of a quantum analysis of soliton fluctuations. The problem is considered with relevance to general difficulties of the quantum error-correction schemes for the classical analogies of the quantum-information processing.

Seth Lloyd

J. P. Gordon

I will discuss the limits imposed by noise on the long-distance transmission of information via optical solitons. Phase noise prohibits the use of phase sensitive systems. Amplitude (energy) noise and timing noise (the Gordon-Haus effect) yield limitations on the information rate. The recent idea of soliton guiding using filters in the line reduces the soliton fluctuations at the expense of increased background noise.