Generating long-lived entangled states with free-space collective spontaneous emission

Collective entangled dark states

Hyper-entangled states and free-space quantum cryptography

We describe the development of a quantum key distribution (QKD) scheme based on ultrafast laser pumped sources of entangled photon pairs and the engineering of their entanglement properties. Though quantum entanglement has been shown to be a useful resource for quantum key distribution, little work has been carried out in making use of the full range of joint entanglement behavior present in hy...

Generating stationary entangled states in superconducting qubits

Jing Zhang,* Yu-xi Liu, Chun-Wen Li, Tzyh-Jong Tarn, and Franco Nori Advanced Science Institute, The Institute of Physical and Chemical Research (RIKEN), Wako-shi, Saitama 351-0198, Japan Department of Automation, Tsinghua University, Beijing 100084, People’s Republic of China CREST, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012, Japan Department of Electrical and Syste...

Generating set for general multipartite entangled states

We propose a entanglement generating set for a general multipartite state based on the of concurrence. In particular, we show that concurrence for general multipartite states can be constructed by different classes of local operators which are defined by complement of positive operator valued measure on quantum phases. The entanglement generating set consists of different classes of entanglemen...

Generating entangled two-photon states with coincident frequencies.

It is shown that parametric down-conversion, with a short-duration pump pulse and a long nonlinear crystal that is appropriately phase matched, can produce a frequency-entangled biphoton state whose individual photons are coincident in frequency. Quantum interference experiments which distinguish this state from the familiar time-coincident biphoton state are described.