Experimental demonstration of optimal universal asymmetric quantum cloning of polarization states of single photons by partial symmetrization

摘要

We report on experimental implementation of the optimal universal asymmetric1->2 quantum cloning machine for qubits encoded into polarization states ofsingle photons. Our linear optical machine performs asymmetric cloning bypartially symmetrizing the input polarization state of signal photon and ablank copy idler photon prepared in a maximally mixed state. We show that theemployed method of measurement of mean clone fidelities exhibits strongresilience to imperfect calibration of the relative efficiencies ofsingle-photon detectors used in the experiment. Reliable characterization ofthe quantum cloner is thus possible even when precise detector calibration isdifficult to achieve.