• Open Access

Quantum Nondemolition Measurements with Optical Parametric Amplifiers for Ultrafast Universal Quantum Information Processing

Ryotatsu Yanagimoto, Rajveer Nehra, Ryan Hamerly, Edwin Ng, Alireza Marandi, and Hideo Mabuchi
PRX Quantum 4, 010333 – Published 29 March 2023

Abstract

Realization of a room-temperature ultrafast photon-number-resolving quantum nondemolition (QND) measurement would have significant implications for photonic quantum information processing, enabling, for example, deterministic quantum computation in discrete-variable architectures, but the requirement for strong coupling has hampered the development of scalable implementations. In this work, we propose and analyze a nonlinear-optical route to photon-number-resolving QND using quadratic (i.e., χ(2)) nonlinear interactions. We show that the coherent pump field driving a frequency-detuned optical parametric amplifier (OPA) experiences displacements conditioned on the number of signal Bogoliubov excitations. A measurement of the pump displacement thus provides a QND measurement of the signal Bogoliubov excitations, projecting the signal mode to a squeezed photon-number state. We then show how our nonlinear OPA dynamics can be utilized to deterministically generate Gottesman-Kitaev-Preskill states with only additional Gaussian resources, offering an all-optical route for fault-tolerant quantum information processing in continuous-variable systems. Finally, we place these QND schemes into a more traditional context by highlighting analogies between the frequency-detuned optical parametric oscillator and multilevel atom-cavity quantum electrodynamics systems by showing how continuous monitoring of the outcoupled pump quadrature induces conditional localization of the intracavity signal mode onto squeezed photon-number states. Our analysis suggests that our proposal may be viable in near-term χ(2) nonlinear nanophotonics, highlighting the rich potential of the OPA as a universal tool for ultrafast non-Gaussian quantum state engineering and quantum computation.

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  • Received 18 October 2022
  • Accepted 8 March 2023

DOI:https://doi.org/10.1103/PRXQuantum.4.010333

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.

Published by the American Physical Society

Physics Subject Headings (PhySH)

Quantum Information, Science & TechnologyAtomic, Molecular & Optical

Authors & Affiliations

Ryotatsu Yanagimoto1,*,‡, Rajveer Nehra2,†,‡, Ryan Hamerly3,4, Edwin Ng1,4, Alireza Marandi2, and Hideo Mabuchi1

  • 1E.L. Ginzton Laboratory, Stanford University, Stanford, California 94305, USA
  • 2Department of Electrical Engineering, California Institute of Technology, Pasadena, California 91125, USA
  • 3Research Laboratory of Electronics, MIT, 50 Vassar Street, Cambridge, Massachusetts 02139, USA
  • 4Physics & Informatics Laboratories, NTT Research, Inc., Sunnyvale, California 94085, USA

  • *ryotatsu@stanford.edu
  • rnehra@caltech.edu
  • These authors contributed equally to this work.

Popular Summary

Compared to conventional quantum computation (QC) platforms (for example, superconducting circuits and trapped ions), photonic qubits can operate at room temperature and transmit over a long distance with little decoherence, offering unprecedented scalability. However, the lack of deterministic and fast nonlinear quantum operations is a major roadblock for all-photonic QC. In this work, we unravel new functions of an optical parametric amplifier (OPA), a widely used component in nonlinear quantum optics, as versatile resolutions to these challenges.

In particular, we study the dynamics of an OPA beyond the conventional regime of weak nonlinearity for applications in ultrafast quantum information processing. We show how an OPA can implement quantum nondemolition (QND) measurements of photon numbers and modular quadrature amplitudes. The photon-number QND measurement enables the implementation of photon-photon entangling gates, one of the most challenging components for photonic QC with discrete-variable encodings. On the other hand, the modular quadrature measurement can be used to generate Gottesman-Kitaev-Preskill qubit states, providing an essential resource for fault-tolerant QC with continuous-variable architecture. These essential operations are performed deterministically, circumventing the clock speed limitations of superconducting detectors in conventional architectures.

Nonlinear optics is inherently broadband, coherent, and room-temperature operable, which are ideal properties for scalable technologies. Our results extending the understanding of the quantum physics of nonlinear optics beyond the conventional theoretical framework could unlock novel functions for ultrafast quantum information science and engineering in a highly scalable manner.

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Vol. 4, Iss. 1 — March - May 2023

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