Free-Fermionic Topological Quantum Sensors

Saubhik Sarkar, Chiranjib Mukhopadhyay, Abhijeet Alase, and Abolfazl Bayat
Phys. Rev. Lett. 129, 090503 – Published 26 August 2022
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Abstract

Second order quantum phase transitions, with well-known features such as long-range entanglement, symmetry breaking, and gap closing, exhibit quantum enhancement for sensing at criticality. However, it is unclear which of these features are responsible for this enhancement. To address this issue, we investigate phase transitions in free-fermionic topological systems that exhibit neither symmetry-breaking nor long-range entanglement. We analytically demonstrate that quantum enhanced sensing is possible using topological edge states near the phase boundary. Remarkably, such enhancement also endures for ground states of such models that are accessible in solid state experiments. We illustrate the results with 1D Su-Schrieffer-Heeger chain and a 2D Chern insulator which are both experimentally accessible. While neither symmetry-breaking nor long-range entanglement are essential, gap closing remains as the major candidate for the ultimate source of quantum enhanced sensing. In addition, we also provide a fixed and simple measurement strategy that achieves near-optimal precision for sensing using generic edge states irrespective of the parameter value. This paves the way for development of topological quantum sensors which are expected to also be robust against local perturbations.

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  • Received 21 January 2022
  • Accepted 5 August 2022

DOI:https://doi.org/10.1103/PhysRevLett.129.090503

© 2022 American Physical Society

Physics Subject Headings (PhySH)

Atomic, Molecular & OpticalQuantum Information, Science & Technology

Authors & Affiliations

Saubhik Sarkar1,*, Chiranjib Mukhopadhyay2,3,†, Abhijeet Alase1,‡, and Abolfazl Bayat3,§

  • 1Institute for Quantum Science and Technology and Department of Physics and Astronomy, University of Calgary, Calgary, Alberta T2N 1N4, Canada
  • 2RCQI, Institute of Physics, Slovak Academy of Sciences, Dúbravská cesta 9, 84511 Bratislava, Slovakia
  • 3Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610051, China

  • *saubhik.sarkar@ucalgary.ca
  • chiranjib.mukhopadhyay@savba.sk
  • abhijeet.alase1@ucalgary.ca
  • §abolfazl.bayat@uestc.edu.cn

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Issue

Vol. 129, Iss. 9 — 26 August 2022

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