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D-Wave Two (project code name Vesuvius) is the second commercially available quantum computer, and the successor to the first commercially available quantum computer, D-Wave One. Both computers were developed by Canadian company D-Wave Systems. The computers are not general purpose, but rather are designed for quantum annealing. Specifically, the computers are designed to use quantum annealing to solve a single type of problem known as quadratic unconstrained binary optimization. As of 2015, it is still heavily debated whether large scale entanglement takes place in D-Wave Two, and whether current or future generations of D-Wave computers will have any advantage over classical computers. D-Wave Two boasts a CPU of approximately 512 qubits—an improvement over the D-Wave One series' CPUs of approximately 128 qubits The number of qubits can vary significantly from chip to chip, due to flaws in manufacturing. The increase in qubit count for the D-Wave Two was accomplished by tiling qubit pattern of the D-Wave One. This pattern, named ''chimera'' by D-Wave Systems, has a limited connectivity such that a given qubit can only interact with at most six other qubits.〔 As with the D-Wave One, this restricted connectivity greatly limits the optimization problems that can be approached with the hardware.〔 In March 2013, several groups of researchers at the Adiabatic Quantum Computing workshop at the Institute of Physics in London produced evidence of quantum entanglement in D-Wave CPUs. Additionally, in March 2014, researchers from University College London and University of Southern California supported that, finding that the D-Wave Two showed the quantum physics outcome that it should while not showing three different classical physics outcomes. In May 2013, Catherine McGeoch verified that D-Wave Two finds solutions to a synthetic benchmark set of Ising spin optimization problems. The results were compared to CPLEX which is a commercial optimization software package capable of proving optimality. Her work was concerned with demonstrating the correctness of the device, but is often being incorrectly cited by public media as a head-to-head benchmark. It has repeatedly been shown that D-Wave Two is no faster than an ordinary laptop. In April 2013, a paper by Boixo demonstrated that simulated annealing only needs about a second on a laptop to solve the type of problems considered by McGeoch.〔 The paper appeared in ''Nature Physics'' in February 2014. Independently, Alex Selby demonstrated that a well-designed heuristic algorithm was about as fast as D-Wave Two in June 2013. In addition Jean-François Puget from IBM demonstrated that running an updated release of CPLEX improved performance under similar conditions by 18 times. Closing the gap somewhat on the 3666X speed-up. Increasing the hardware resources in the form of additional parallel threads improved CPLEX performance further. A D-Wave Two in the Quantum Artificial Intelligence Lab at the NASA Advanced Supercomputing Division of Ames Research Center is used for research into machine learning and related fields of study. NASA, Google, and the Universities Space Research Association (USRA) started the lab in 2013. ==References== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「D-Wave Two」の詳細全文を読む スポンサード リンク
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