An unknown state of a quantum system S is usually determined by repeatedly measuring a set of non-commuting observables. The state can also be obtained from the repeated measurements of a single separable observable w...An unknown state of a quantum system S is usually determined by repeatedly measuring a set of non-commuting observables. The state can also be obtained from the repeated measurements of a single separable observable when the system S interacts with an assistant system A in a known state. In this paper, we study the quantum state tomography of a three-level atom （the system S） interacting with two radiation fields as the assistant system A. We obtain the initial state of S by repeatedly measuring a separable observable O = Sz n1 n2, in which Sz is the atom operator, and hi and h2 are the photon number operators of the two radiation fields. We achieve the one-to-one mapping M between the initial density matrix of the system S and the measured results of the single separable observable. We also give a concrete numerical example.展开更多
基金the National Natural Science Foundation of China (Grant Nos. 60978009 and 91121023)the National Basic Research Program of China (Grant No. 2011CBA00200)
文摘An unknown state of a quantum system S is usually determined by repeatedly measuring a set of non-commuting observables. The state can also be obtained from the repeated measurements of a single separable observable when the system S interacts with an assistant system A in a known state. In this paper, we study the quantum state tomography of a three-level atom （the system S） interacting with two radiation fields as the assistant system A. We obtain the initial state of S by repeatedly measuring a separable observable O = Sz n1 n2, in which Sz is the atom operator, and hi and h2 are the photon number operators of the two radiation fields. We achieve the one-to-one mapping M between the initial density matrix of the system S and the measured results of the single separable observable. We also give a concrete numerical example.
