Quantum Discord Could Facilitate Remote Preparation of Quantum States

By Will SoutterAug 8 2012

Collaborative research between the University of Vienna, the Institute for Quantum Optics and Quantum Information (IQOQI) of the Austrian Academy of Sciences, the Vienna Center for Quantum Science and Technology (VCQ), the University of Oxford and the Centre for Quantum Technologies at the National University of Singapore demonstrate the possibility of remote preparation of quantum states as a result of quantum discord.

The basic premise of quantum physics is that the correlation between two or more particles is stronger than that entertained classically. The basis of remote state preparation is this correlation feature which causes changes in the state of a particle entangled with another particle that is being measured. The change in state takes place irrespective of the distance between the entangled particles. This ability to allow remote preparation of quantum state has great significance in quantum computation, quantum cryptography and quantum communication. The team of researchers at the University of Vienna has however shown that entanglement is not the only route to remote state preparation. In fact, systems with strong entanglement are difficult to prepare or control as they are very sensitive to external influence. According to the researchers, the existence of quantum discord or disturbance amongst correlated particles while being measured is sufficient for remote state preparation. They employed a number of two-photon states with varied polarization correlations and found that variations in the quantum discord affected the quality of the remotely prepared states. This work could pave the way for quantum information processing techniques employing simple resources.