%0 Journal Article %D 2021 %T Precise Hamiltonian identification of a superconducting quantum processor %A Dominik Hangleiter %A Ingo Roth %A Jens Eisert %A Pedram Roushan %X

The required precision to perform quantum simulations beyond the capabilities of classical computers imposes major experimental and theoretical challenges. Here, we develop a characterization technique to benchmark the implementation precision of a specific quantum simulation task. We infer all parameters of the bosonic Hamiltonian that governs the dynamics of excitations in a two-dimensional grid of nearest-neighbour coupled superconducting qubits. We devise a robust algorithm for identification of Hamiltonian parameters from measured times series of the expectation values of single-mode canonical coordinates. Using super-resolution and denoising methods, we first extract eigenfrequencies of the governing Hamiltonian from the complex time domain measurement; next, we recover the eigenvectors of the Hamiltonian via constrained manifold optimization over the orthogonal group. For five and six coupled qubits, we identify Hamiltonian parameters with sub-MHz precision and construct a spatial implementation error map for a grid of 27 qubits. Our approach enables us to distinguish and quantify the effects of state preparation and measurement errors and show that they are the dominant sources of errors in the implementation. Our results quantify the implementation accuracy of analog dynamics and introduce a diagnostic toolkit for understanding, calibrating, and improving analog quantum processors.

%8 8/18/2021 %G eng %U https://arxiv.org/abs/2108.08319 %0 Journal Article %D 2019 %T Quantum Simulators: Architectures and Opportunities %A Ehud Altman %A Kenneth R. Brown %A Giuseppe Carleo %A Lincoln D. Carr %A Eugene Demler %A Cheng Chin %A Brian DeMarco %A Sophia E. Economou %A Mark A. Eriksson %A Kai-Mei C. Fu %A Markus Greiner %A Kaden R. A. Hazzard %A Randall G. Hulet %A Alicia J. Kollár %A Benjamin L. Lev %A Mikhail D. Lukin %A Ruichao Ma %A Xiao Mi %A Shashank Misra %A Christopher Monroe %A Kater Murch %A Zaira Nazario %A Kang-Kuen Ni %A Andrew C. Potter %A Pedram Roushan %X

Quantum simulators are a promising technology on the spectrum of quantum devices from specialized quantum experiments to universal quantum computers. These quantum devices utilize entanglement and many-particle behaviors to explore and solve hard scientific, engineering, and computational problems. Rapid development over the last two decades has produced more than 300 quantum simulators in operation worldwide using a wide variety of experimental platforms. Recent advances in several physical architectures promise a golden age of quantum simulators ranging from highly optimized special purpose simulators to flexible programmable devices. These developments have enabled a convergence of ideas drawn from fundamental physics, computer science, and device engineering. They have strong potential to address problems of societal importance, ranging from understanding vital chemical processes, to enabling the design of new materials with enhanced performance, to solving complex computational problems. It is the position of the community, as represented by participants of the NSF workshop on "Programmable Quantum Simulators," that investment in a national quantum simulator program is a high priority in order to accelerate the progress in this field and to result in the first practical applications of quantum machines. Such a program should address two areas of emphasis: (1) support for creating quantum simulator prototypes usable by the broader scientific community, complementary to the present universal quantum computer effort in industry; and (2) support for fundamental research carried out by a blend of multi-investigator, multi-disciplinary collaborations with resources for quantum simulator software, hardware, and education. 

%8 12/14/2019 %G eng %U https://arxiv.org/abs/1912.06938