  Quantum state privacy amplification (QSPA) is the quantum analogue of
classical privacy amplification. If the state information of a series of single
particle states has some leakage, QSPA reduces this leakage by condensing the
state information of two particles into the state of one particle. Recursive
applications of the operations will eliminate the quantum state information
leakage to a required minimum level. In this paper, we report the experimental
implementation of a quantum state privacy amplification protocol in a nuclear
magnetic resonance system. The density matrices of the states are constructed
in the experiment, and the experimental results agree with theory well.
