Experimental realization of multipartite entanglement of 60 modes of a quantum optical frequency comb

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We report the experimental realization and characterization of one 60-mode copy, and of two 30-mode copies, of a dual-rail quantum-wire cluster state in the quantum optical frequency comb of a bimodally pumped optical parametric oscillator.

• This is the largest entangled system ever created whose subsystems are all available simultaneously.
• The entanglement proceeds from the coherent concatenation of a multitude of EPR pairs by a single beam splitter, a procedure which is also a building block for the realization of hypercubic-lattice cluster states for universal quantum computing.