Efficient one-out-of-two quantum oblivious transfer based on four-coherent-state postselection protocol

On the basis of the modified four-coherent-state post-selection quantum key distribution protocol (Namiki and Hirano 2006 Preprint quant-ph/0608144v1), two 1-out-of-2 quantum oblivious transfer (QOT₂ ¹) protocols are proposed. The first proposed protocol (called the receiver-based QOT ₂ ¹ protocol) requires the coherent states to be prepared by the receiver, whereas the second protocol (called the sender-based QOT ₂ ¹ protocol) allows the coherent states to be generated by the sender. The main advantages of the proposed protocols are that (i) no quantum bit commitment schemes and the assumption of quantum memory are needed; (ii) less communication cost between participants is required, i.e. the receiver-based QOT₂ ¹ protocol requires only one quantum communication and one classical communication and the sender-based QOT ₂ ¹ protocol requires only one quantum communication between participants during protocol execution; and (iii) the utilization of quantum states is very efficient, wherein the receiver-based and the sender-based QOT₂ ¹ protocols use only two coherent pulses and one coherent pulse respectively for sending the sender's two messages.