Holon Physics Seminar

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The generation of entanglement between more than two particles is a major challenge for all physical realizations. It is required for the realization of many quantum information protocols, including quantum computing. Single photons are one of the most promising realizations of quantum bits (qubits), as they are easily manipulated and preserve their coherence for long times.

 

Quantum information can be stored in many different degrees of freedom of the photons. Only recently, ten photons were entangled in a single state through their polarization degree of freedom. The main difficulties in increasing this number are the elaborated setups required and the low rates of state production. I will present two novel and simple schemes that can in principle generate entanglement between any number of photons from a single fixed setup.

 

These schemes combine photons from one source, but at different times, using an optical delay. The second scheme can be extended to create higher-dimensional cluster states, and even arbitrary graph states. Such states are useful for the one-way quantum computer scheme. Results from such a setup using heralded single photons will be presented. States of two and three entangled photons were measured, with good visibilities of their quantum interference.