Department of Physics, University of California, Santa Barbara, CA 93106-9530, USA.
Science. 2011 Oct 7;334(6052):61-5. doi: 10.1126/science.1208517. Epub 2011 Sep 1.
The von Neumann architecture for a classical computer comprises a central processing unit and a memory holding instructions and data. We demonstrate a quantum central processing unit that exchanges data with a quantum random-access memory integrated on a chip, with instructions stored on a classical computer. We test our quantum machine by executing codes that involve seven quantum elements: Two superconducting qubits coupled through a quantum bus, two quantum memories, and two zeroing registers. Two vital algorithms for quantum computing are demonstrated, the quantum Fourier transform, with 66% process fidelity, and the three-qubit Toffoli-class OR phase gate, with 98% phase fidelity. Our results, in combination especially with longer qubit coherence, illustrate a potentially viable approach to factoring numbers and implementing simple quantum error correction codes.
冯·诺依曼架构的经典计算机包括中央处理器和存储指令与数据的存储器。我们展示了一种量子中央处理器，它与芯片上集成的量子随机存取存储器交换数据，指令存储在经典计算机上。我们通过执行涉及七个量子元件的代码来测试我们的量子机器：两个通过量子总线耦合的超导量子比特，两个量子存储器和两个清零寄存器。展示了两种对于量子计算至关重要的算法，量子傅立叶变换，其保真度为 66%，以及三量子比特托弗利类或相位门，其相位保真度为 98%。我们的结果，特别是与更长的量子相干性相结合，说明了一种有前途的方法，可以用于分解数字和实现简单的量子错误纠正码。
