Nigg, Simon

Friday Jan 11, 2013
Time: 11:00
Place: ETH Science City, HIT E 41.1
Host:  Stefan Filipp / Andreas Wallraff

Stabilizer quantum error correction toolbox for superconducting qubits

Simon E. Nigg
Department of Physics, Yale University, CT, USA

Rudimentary quantum error correction (QEC) has been achieved in a superconducting qubit circuit [1]. Realization of topological protection and QEC based on stabilizer codes will require protocols for QND measurement of multi-qubit Pauli operators on arbitrary selected subsets of qubits. Initial progress towards this goal has been achieved with four-qubit stabilizer pumping in a trapped ion system [2]. We present a general protocol for stabilizer measurement and pumping in a system of N  superconducting qubits. We assume always-on, fixed dispersive couplings  to a single mode of a high-Q microwave resonator in the ultra-strong dispersive limit defined by  ≫ 1/T2, , where T2 is the qubit coherence time and  is the cavity line width. In this limit, we show how to measure an arbitrary weight M ≤ N Pauli operator, by mapping its two eigenvalues onto two distinguishable coherent states of the cavity. Together with a fast cavity readout (Tmeas ≪ 1/), this enables the efficient measurement of mulit-qubit Pauli operators. This work was supported by the Swiss NSF, the US NSF DMR-1004406 and ARO W911NF-09-1-0514.

[1] M. D. Reed et al. Realization of three-qubit quantum error correction with superconducting circuits, Nature 2012, 482, 382-385
[2] J. T. Barreiro et al. An open-system quantum simulator with trapped ions, Nature 2011, 470, 486