Experimental quantum information processing

Until recently, quantum mechanics played only a marginal and auxiliary role in information processing. Laws of quantum physics were improtant for construction of semiconductor devices but the computer architecture remained essentially classical. Gradually, however, it was discovered that certain strange quantum phenomena allow to process and transmit information in ways that are unthinkable of in classical information theory. The most interesting potential applications include quantum cryptography and quantum computing. Quantum cryptography provides provably secure communication. Quantum computers may solve certain types of problems (such as the factorization of large numbers) much more efficiently than any known classical algorithm. Other interesting methods of quantum information processing include quantum state teleportation, quantum error correction codes, cloning of quantum states, etc. Quantum optics is a very powerful tool both for the  investigation of fundamental aspects of quantum theory, such as quantum coherence and entanglement, and for the construction of quantum information processing devices.

Our laboratory is involved in experimental studies of the properties of entangled states and interference at the single-photon level, and experimental realization of elementary quantum operations useful for quantum information processing. In previous years, we have focused on the optimal copying of quantum states of photons, quantum lossy compression, the implementation of so-called quantum multimeter and programmable quantum discriminator or direct measurement of the overlap of two polarization states of photons. 

Our recent experiments include demonstration of noiseless loss suppression in quantum optical communication, increasing efficiency of a linear-optical quantum gate using electronic feed-forward, test of a highly non-classical character of a heralded single-photon state and implementation of programmable quantum gates with single- and two-qubit program register..