01017nas a2200181 4500008003900000022001400039245002400053210002400077300001100101490000900112520054600121100001400667700002200681700002400703700001800727700001300745856007700758 2010 d a0031-894900aRecycling of qubits0 aRecycling of qubits a0140590 vT1403 aWe consider a finite number, N, of qubits that encode a pure single qubit state SU(2) covariantly. Given the N-qubit state has already been measured optimally to estimate the single-qubit state, we analyse the maximum information obtainable by a second, and subsequent observers ignorant of important details of the previous measurements. We quantify the information acquired by each observer as a function of N and of the number of independent observers that in succession have independently measured the same ensemble of qubits before him.1 aRapcan, P1 aCalsamiglia, John1 aMuĂ±oz-Tapia, Ramon1 aBagan, Emilio1 aBuzek, V uhttp://iopscience.iop.org/1402-4896/2010/T140/014059?fromSearchPage=true