TY - Generic T1 - Experimental Comparison of Two Quantum Computing Architectures T2 - Proceedings of the National Academy of Sciences Y1 - 2017 A1 - N.M. Linke A1 - Dmitri Maslov A1 - Martin Roetteler A1 - S. Debnath A1 - C. Figgatt A1 - K. A. Landsman A1 - K. Wright A1 - Christopher Monroe AB -

We run a selection of algorithms on two state-of-the-art 5-qubit quantum computers that are based on different technology platforms. One is a publicly accessible superconducting transmon device [1] with limited connectivity, and the other is a fully connected trapped-ion system [2]. Even though the two systems have different native quantum interactions, both can be programmed in a way that is blind to the underlying hardware, thus allowing the first comparison of identical quantum algorithms between different physical systems. We show that quantum algorithms and circuits that employ more connectivity clearly benefit from a better connected system of qubits. While the quantum systems here are not yet large enough to eclipse classical computers, this experiment exposes critical factors of scaling quantum computers, such as qubit connectivity and gate expressivity. In addition, the results suggest that co-designing particular quantum applications with the hardware itself will be paramount in successfully using quantum computers in the future.

JA - Proceedings of the National Academy of Sciences VL - 114 U4 - 3305-3310 UR - http://www.pnas.org/content/114/13/3305 U5 - 10.1073/pnas.1618020114 ER - TY - JOUR T1 - Demonstration of a small programmable quantum computer with atomic qubits JF - Nature Y1 - 2016 A1 - S. Debnath A1 - N. M. Linke A1 - C. Figgatt A1 - K. A. Landsman A1 - K. Wright A1 - C. Monroe AB -

Quantum computers can solve certain problems more efficiently than any possible conventional computer. Small quantum algorithms have been demonstrated on multiple quantum computing platforms, many specifically tailored in hardware to implement a particular algorithm or execute a limited number of computational paths. Here, we demonstrate a five-qubit trapped-ion quantum computer that can be programmed in software to implement arbitrary quantum algorithms by executing any sequence of universal quantum logic gates. We compile algorithms into a fully-connected set of gate operations that are native to the hardware and have a mean fidelity of 98 %. Reconfiguring these gate sequences provides the flexibility to implement a variety of algorithms without altering the hardware. As examples, we implement the Deutsch-Jozsa (DJ) and Bernstein-Vazirani (BV) algorithms with average success rates of 95 % and 90 %, respectively. We also perform a coherent quantum Fourier transform (QFT) on five trappedion qubits for phase estimation and period finding with average fidelities of 62 % and 84 %, respectively. This small quantum computer can be scaled to larger numbers of qubits within a single register, and can be further expanded by connecting several such modules through ion shuttling or photonic quantum channels.

VL - 536 U4 - 63-66 UR - http://www.nature.com/nature/journal/v536/n7614/full/nature18648.html CP - 7614 U5 - 10.1038/nature18648 ER -