An efficient circle-type multiparty quantum key agreement protocol with single particles

An efficient circle-type multiparty quantum key agreement protocol utilizing two non-orthogonal bases single particles is proposed. In our protocol, each participant performs one of two simple unitary operations to encode and additional unitary operations to protect his privacy. Both outside attacks and participant attacks can be perfectly resisted. Moreover, our protocol has a high efficiency up to [Formula: see text], where [Formula: see text] is the number of the participants, and it can be easily implemented with current quantum technologies as it needs only single particle measurements.