Experimental demonstration of measurement-based quantum computation in correlation space

Date: 2010-04-23
Authors Wei-Bo Gao, Xing-Can Yao, Jian-Ming Cai, He Lu, Ping Xu, Tao Yang, Yu-Ao Chen, Zeng-Bing Chen and Jian-Wei Pan
Journal No. arXiv:1004.4162
Abstract The paradigm of measurement-based quantum computation opens new experimental avenues to realize a quantum computer and deepens the understanding of quantum physics. For years, the entanglement properties of cluster states have been considered critical for universal measurement- based quantum computation. Surprisingly, a novel framework namely quantum computation in correlation space has opened new routes to construct quantum states possessing entanglement properties different from cluster states while still retaining the universality for measurement-based quantum computing. The scheme not only offers more flexibility to prepare universal resources for quantum computation, but also provides a different perspective to study the fundamental problem regarding what are the essential features responsible for the speedup of quantum computers over classical devices. Here we report an experimental realization of every building block of the model of measurement-based quantum computation in correlation space. In the experiment, we prepare a four-qubit and a six-qubit state, which are proved different from cluster states through two-point correlation functions and the single site entropy of the qubits. With such resources, we have demonstrated a universal set of single-qubit rotations, two-qubit entangling gates and further Deutsch's algorithm. Besides being of fundamental interest, our experiment proves in-principle the feasibility of universal measurement-based quantum computation without cluster states, which represents a new approach towards the realization of a quantum computer.