Optimal control of quantum superpositions in a bosonic Josephson junction

Abstract

International audienceWe show how to optimally control the creation of quantum superpositions in a bosonic Josephson junction within the two-site Bose-Hubbard-model framework. Both geometric and purely numerical optimal-control approaches are used, the former providing a generalization of the proposal of Micheli et al. [Phys. Rev. A 67, 013607 (2003)]. While this method is shown not to lead to significant improvements in terms of time of formation and fidelity of the superposition, a numerical optimal-control approach appears more promising, as it allows creation of an almost perfect superposition, within a time short compared to other existing protocols. We analyze the robustness of the optimal solution against atom-number variations. Finally, we discuss the extent to which these optimal solutions could be implemented with state-of-the-art technology

Fully efficient time-parallelized quantum optimal control algorithm

“…Molecular orientation [33,34] is nowadays a wellestablished topic both from the experimental [35,36] and theoretical points of views [37][38][39][40][41]. Different optimal control analyses have been made on this quantum system [42][43][44][45].…”

“…This subject has been extensively studied in the past few years [51,52,[54][55][56][57][58]. Following Ref.…”

Observation of the field-free orientation of a symmetric-top molecule by terahertz laser pulses at high temperature

“…At low temperature, a very high degree of orientation can be obtained using such control strategies and a molecular quantum-state selection [32,33,34,35]. Control schemes in the sudden regime, where the duration of the control field is short with respect to the rotational period, have been also developed [36,37,38,39,40,12,41,42,43,44,45,46,47,48,49,50,51,52]. Among other techniques, we can mention the interaction of the molecule with a terahertz (THz) laser pulse and the (ω, 2ω)-scheme.…”

“…This molecule is a good candidate to achieve a high degree of orientation at room temperature due to its large permanent dipole moment and its relatively small rotational constant [43]. The THz pulses are obtained from the excitation of a plasma by a two-color femtosecond laser field [58], while the detection process is based on the free-induction decay (FID) emitted by the molecular sample after the THz excitation [59,60,61,62].…”

Comparative study of monotonically convergent optimization algorithms for the control of molecular rotation

“…The control of molecular rotation [26,27,28,29,30,31,32,33], for which such non-linear models are well established [34,35], is used as a testbed case to analyze the features of these algorithms. A first modification of a monotonically convergent algorithm to account for a non-linear interaction with the control assumes the cost to be quadratic in the field and decomposes the control into n components for a nonlinearity of order n [24].…”