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arXiv · 1803.01014

Measurement of a Superconducting Qubit with a Microwave Photon Counter

A. Opremcak·I. V. Pechenezhskiy·C. Howington·B. G. Christensen·M. A. Beck·E. Leonard Jr.·J. Suttle·C. Wilen·K. N. Nesterov·G. J. Ribeill·T. Thorbeck·F. Schlenker·M. G. Vavilov·B. L. T. Plourde·R. McDermott
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Abstract

Fast, high-fidelity measurement is a key ingredient for quantum error correction. Conventional approaches to the measurement of superconducting qubits, involving linear amplification of a microwave probe tone followed by heterodyne detection at room temperature, do not scale well to large system sizes. Here we introduce an alternative approach to measurement based on a microwave photon counter. We demonstrate raw single-shot measurement fidelity of 92%. Moreover, we exploit the intrinsic damping of the counter to extract the energy released by the measurement process, allowing repeated high-fidelity quantum non-demolition measurements. Crucially, our scheme provides access to the classical outcome of projective quantum measurement at the millikelvin stage. In a future system, counter-based measurement could form the basis for a scalable quantum-to-classical interface.

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A. Opremcak, I. V. Pechenezhskiy, C. Howington, B. G. Christensen, M. A. Beck, E. Leonard Jr., J. Suttle, C. Wilen, K. N. Nesterov, G. J. Ribeill, T. Thorbeck, F. Schlenker, M. G. Vavilov, B. L. T. Plourde, R. McDermott. 2018-03-02. Measurement of a Superconducting Qubit with a Microwave Photon Counter. https://doi.org/10.1126/science.aat4625

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