98 citations · 1.2k across the 60 of their papers we have counts for
6 papers · 1 filter
Knowing "where the photons have been"
Karol Bartkiewicz, Antonín Černoch, Dalibor Javůrek +3
Linear-optical interferometers play a key role in designing circuits for quantum information processing and quantum communications. Even though nested Mach-Zehnder interferometers…
Quantifying entanglement of a two-qubit system via measurable and invariant moments of its partially transposed density matrix
Karol Bartkiewicz, Jiří Beran, Karel Lemr +2
We describe a direct method to determine the negativity of an arbitrary two-qubit state in experiments. The method is derived by analyzing the relation between the purity, negativi…
Experimental implementation of optimal linear-optical controlled-unitary gates
Karel Lemr, Karol Bartkiewicz, Antonín Černoch +2
We show that it is possible to reduce the number of two-qubit gates needed for the construction of an arbitrary controlled-unitary transformation by up to two times using a tunable…
Luminescence-induced noise in single photon sources based on BBO crystals
Radek Machulka, Karel Lemr, Ondřej Haderka +3
Single-photon sources based on the process of spontaneous parametric down-conversion play a key role in various applied disciplines of quantum optics. We characterize intrinsic lum…
Method for universal detection of two-photon polarization entanglement
Karol Bartkiewicz, Paweł Horodecki, Karel Lemr +2
Detecting and quantifying quantum entanglement of a given unknown state poses problems that are fundamentally important for quantum information processing. Surprisingly, no direct…
Using quantum routers to implement quantum message authentication and Bell-state manipulation
Karol Bartkiewicz, Antonín Černoch, Karel Lemr
In this paper we investigate the capability of quantum routing (quantum state fusion) to implement two useful quantum communications protocols. The analyzed protocols include quant…