We study the capacity of quantum private information retrieval (QPIR) with multiple servers. In QPIR problem servers, a user retrieves classical file by downloading systems from servers each which contains copy set while identity downloaded is not leaked to server. The defined as maximum rate size over whole dimension systems. When are assumed share prior entanglement, we prove that 1 regardles...

We consider two-stage tandem queuing systems with dedicated servers in each station and flexible servers that can serve in both stations. We assume exponential service times, linear holding costs, and operating costs incurred by the servers at rates proportional to their speeds. Under conditions that ensure the optimality of nonidling policies, we show that the optimal allocation of flexible se...

We consider a system of parallel servers handling users of various classes, whose service rates depend not only on user classes, but also on the set of active servers. We investigate the stability under two types of allocation strategies: (i) server assignment where the users are assigned to servers based on rates, load, and other considerations, and (ii) coordinated scheduling where the activi...