Quantum solitons as possible qubits

Mild Wadatlt

Muzzamal Iqbal Shaukat, Eduardo V. Castro, Hugo Terças

We study the possibility of using dark soliton in quasi one dimensional Bose Einstein condensates to produce two level system (qubits) by exploiting the intrinsic nonlinear and the coherent nature of the matter waves. We calculate the soliton spectrum and the conditions for a qubit to exist. We also compute the coupling between the phonons and the soliton and investigate the emission rate of the qubits in that case. Remarkably, the qubit lifetime is estimated to be of the order of a few seconds, being by the dark soliton "death" due to quantum evaporation.

Andreas Sizmann

Alessandro Cuccoli, Davide Nuzzi, Ruggero Vaia +1 more

Propagation of soliton-like excitations along spin chains has been proposed as a possible way for transmitting both classical and quantum information between two distant parties with negligible dispersion and dissipation. In this work, a somewhat different use of solitons is considered. Solitons propagating along a spin chain realize an effective magnetic field, well localized in space and time, which can be exploited as a means to manipulate the state of an external spin (i.e., a qubit) that is weakly coupled to the chain. We have investigated different couplings between the qubit and the chain, as well as different soliton shapes, according to a Heisenberg chain model. It is found that symmetry properties strongly affect the effectiveness of the proposed scheme, and the most suitable setups for implementing single qubit quantum gates are singled out.

Banasri Basu, P. Bandyopadhyay

Andrzej Janutka

The polarization of a multi-component vector soliton (of the Manakov type) can be thought of as a state vector of a system of qubits (a register of quantum information). A change of this state on demand via colliding the register pulse with other solitons is shown to be possible with arbitrary accuracy. The parameters (polarization, pulse width, velocity) of the register-switching solitons corresponding to the computationally universal set of quantum gates are found. Physical realizations of information processing using effects of the self-focusing of optical media or of the self-induced transparency are considered.