Noise is unavoidable in practice and its presence makes quantum protocols imperfect. In this paper we consider a way to cope with typical types of noise in joint remote preparation of an arbitrary 2-qubit state. The idea is to use nonmaximally (in stead of maximally) entangled states as the initial quantum channel. | Communications in Physics, Vol. 28, No. 1 (2018), pp. 1-19 DOI: Invited Paper COPING WITH NOISE IN JOINT REMOTE PREPARATION OF A GENERAL TWO-QUBIT STATE BY USING NONMAXIMALLY ENTANGLED QUANTUM CHANNEL DAT THANH LE1 , HOP VAN NGUYEN2 AND AN BA NGUYEN1,3,† 1 Thang Long Institute of Mathematics and Applied Sciences, Thang Long University, Nghiem Xuan Yem, Hoang Mai, Hanoi, Vietnam 2 Department of Physics, Hanoi National University of Education, 136 Xuan Thuy, Cau Giay, Hanoi, Vietnam 3 Institute of Physics, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam † E-mail: nban@ Received 17 February 2018 Accepted for publication 17 March 2018 Published 26 March 2018 Abstract. Noise is unavoidable in practice and its presence makes quantum protocols imperfect. In this paper we consider a way to cope with typical types of noise in joint remote preparation of an arbitrary 2-qubit state. The idea is to use nonmaximally (in stead of maximally) entangled states as the initial quantum channel. Because noise changes the initial quantum channel we can beforehand tailor it to be nonmaximally entangled by introducing free parameters which, depending on given types of noise, can be controlled so that due to the affect of noise the initial quantum channel becomes closest to the maximally entangled one, thus optimizing the performance of the joint remote state preparation protocol. The dependence of the optimal averaged fidelities on the strength of various types of noise is represented by phase diagrams that clearly separate the quantum domain from the classical one. Keywords: joint remote state preparation, two-qubit state, noise. Classification numbers: . c 2018 Vietnam Academy of Science and Technology 2 DAT THANH LE, HOP VAN NGUYEN AND AN BA NGUYEN I. INTRODUCTION Multiparty remote state preparation [1] or joint remote state preparation (JRSP) [2] or collective remote state preparation
