Continuous measurements for control of superconducting quantum circuits

S. Hacohen-Gourgy, L. S. Martin

Research output: Contribution to journalReview articlepeer-review

Abstract

Developments over the last two decades have opened the path towards quantum technologies in many quantum systems, such as cold atoms, trapped ions, cavity-quantum electrodynamics (QED), and circuit-QED. However, the fragility of quantum states to the effects of measurement and decoherence still poses one of the greatest challenges in quantum technology. An imperative capability in this path is quantum feedback, as it enhances the control possibilities and allows for prolonging coherence times through quantum error correction. While changing parameters from shot to shot of an experiment or procedure can be considered feedback, quantum mechanics also allows for the intriguing possibility of performing feedback operations during the measurement process itself. This broader approach to measurements leads to the concepts of weak measurement, quantum trajectories, and numerous types of feedback with no classical analogs. These types of processes are the primary focus of this review. We introduce the concept of quantum feedback in the context of circuit-QED, an experimental platform with significant potential in quantum feedback and technology. We then discuss several experiments and see how they elucidate the concepts of continuous measurements and feedback. We conclude with an overview of coherent feedback, with application to fault-tolerant error correction.

Original languageEnglish
Article number1813626
JournalAdvances in Physics: X
Volume5
Issue number1
DOIs
StatePublished - 1 Jan 2020

Keywords

  • Circuit-QED
  • continuous measurement
  • quantum control
  • quantum feedback
  • superconducting qubits

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy

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