Mainz 2017 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 1: Quantum Information: Concepts and Methods I

Q 1.4: Vortrag

Montag, 6. März 2017, 15:45–16:00, P 2

Randomized Benchmarking with symmetries — •Emilio Onorati¹, Albert H. Werner², and Jens Eisert¹ — ¹Dahlem Center for Complex Quantum Systems, Freie Universität Berlin, Germany — ²Department of Mathematical Sciences, University of Copenhagen, Denmark

A central step toward the realization of quantum information processing devices is the estimation of the accuracy in the implementation of unitary gates. While a complete characterization of any quantum operation may be obtained through quantum process tomography, this approach suffers from two major shortcomings: SPAM errors sensitivity and exponentially growing necessary resources. Randomized benchmarking has become a standard technique to overcome these limitations. The method involves the measurement of density operators after application of a random sequence of gates, chosen from the Clifford or other small groups, which drastically reduces the number of needed parameters. While randomized benchmarking has proven to be successful in numerous experiments, the initial assumptions of the protocol are demanding: up to small perturbations, the average error is assumed to be both gate- and time-independent with respect to all gates. We propose a novel approach to overcome these issues: by exploiting the symmetries of the gates to be benchmarked, we are able to estimate the error of each operator individually. To this aim, knowledge regarding the representation theory of the symmetry group is necessary; nevertheless, we investigate how well-known and small groups allow for the characterization of a large number of multi-qubit gates.