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Ultrafast all-optical measurement of squeezed vacuum in a lithium niobate nanophotonic circuit

James Williams1,*, Elina Sendonaris2,*, Rajveer Nehra1,3,4,5, Robert M. Gray1, Ryoto Sekine1, Luis Ledezma1, and Alireza Marandi1,2,†

  • *These authors contributed equally to this work.
  • †Contact author: marandi@caltech.edu
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Phys. Rev. Research 7, 043006 – Published 1 October, 2025

DOI: https://doi.org/10.1103/rvmb-ljd3

Abstract

Squeezed vacuum, a fundamental resource for continuous-variable quantum information processing, has been used to demonstrate quantum advantages in sensing, communication, and computation. While most experiments use homodyne detection to characterize squeezing and are therefore limited to electronic bandwidths, recent experiments have shown optical parametric amplification (OPA) to be a viable measurement strategy. Here, we realize OPA-based quantum state tomography in integrated photonics and demonstrate the generation and all-optical Wigner tomography of squeezed vacuum in a nanophotonic circuit. We employ dispersion engineering to enable the distortion-free propagation of femtosecond pulses and achieve ultrabroad operation bandwidths, effectively lifting the speed restrictions imposed by traditional electronics on quantum measurements with a theoretical maximum clock speed of 6.5 THz. We implement our circuit on thin-film lithium niobate, a platform compatible with a wide variety of active and passive photonic components. Our results chart a course for realizing all-optical ultrafast quantum information processing in an integrated room-temperature platform.

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Outline

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Phys. Rev. Research 7, 043006– Published 1 October, 2025
  • Received 5 February 2025
  • Accepted 27 August 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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