Optimal quantum control with multi-polarization fields

Ze-Xia Huang, Huang Decai, You-Hong Yu

Gabriel Turinici, HERSCHEL A. RABITZ

Abstract. In this work we analyze the quantum controllability of rotational motion under the influence of an external laser field coupled through a permanent dipole moment. The analysis takes into consideration up to three polarization fields, but we also discuss the consequences for working with fewer polarized fields. Multi-polarization quantum control of rotational motion through dipole coupling 2

Anatoliy G. Butkovskiy, Yu. I. Samoilenko

Jinfang Li, Jie‐Ru Hu, Feng Wan +1 more

Implementation of quantum gates are important for quantum computations in physical system made of polar molecules. We investigate the feasibility of implementing gates based on pendular states of the molecular system by two different quantum optical control methods. Firstly, the Multi-Target optimal control theory and the Multi-Constraint optimal control theory are described for optimizing control fields and accomplish the optimization of quantum gates. Numerical results show that the controlled NOT gate (CNOT) can be realized under the control of above methods with high fidelities (0.975 and 0.999) respectively. In addition, in order to examine the dependence of the fidelity on energy difference in the same molecular system, the SWAP gate in the molecular system is also optimized with high fidelity (0.999) by the Multi-Constraint optimal control theory with the zero-area and constant-fluence constraints.

V. P. Belavkin, Simon Edwards

Jie‐Ru Hu, Zuo-Yuan Zhang, Jin‐Ming Liu +1 more

Quantum algorithms can afford greater computational efficiency compared to their classical counterparts when addressing specific computing tasks. We describe here the implementation, using a polar molecule in an external electric field, of the single-qudit cyclic permutation identification algorithm proposed by Gedik et al. [ Sci. Rep. 5 , 14671 ( 2015 ). 10.1038/srep10995 ]. A molecular ququart is realized through the field-dressed states generated as the pendular modes of BaI. By employing multi-target optimal control theory, we design microwave pulses for ququart-based operations such as the Fourier transformation and its inverse, as well as the oracle U f operation. Specifically, we design an optimized pulse sequence that realizes a quantum algorithm on a single BaI molecule identifying the parity of a member of a set of cyclic permutations with high fidelity. This demonstrates the applicability of optimal control theory to polar molecules for quantum computation.