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arXiv · 2209.01114

Quantum nondemolition measurements with optical parametric amplifiers for ultrafast universal quantum information processing

Ryotatsu Yanagimoto·Rajveer Nehra·Ryan Hamerly·Edwin Ng·Alireza Marandi·Hideo Mabuchi
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Abstract

Realization of a room-temperature ultra-fast photon-number-resolving (PNR) quantum nondemolition (QND) measurement would have significant implications for photonic quantum information processing (QIP), enabling, e.g., 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 PNR QND using quadratic (i.e., $\chi^{(2)}$) nonlinear interactions. We show that the coherent pump field driving a phase-mismatched 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 for deterministically generating Gottesman-Kitaev-Preskill states only with additional Gaussian resources, offering an all-optical route for fault-tolerant QIP in continuous-variable systems. Finally, we place these QND schemes into a more traditional context by highlighting analogies between the phase-mismatched optical parametric oscillator and multilevel atom-cavity QED 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 $\chi^{(2)}$ nonlinear nanophotonics, highlighting the rich potential of OPA as a universal tool for ultrafast non-Gaussian quantum state engineering and quantum computation.

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Ryotatsu Yanagimoto, Rajveer Nehra, Ryan Hamerly, Edwin Ng, Alireza Marandi, Hideo Mabuchi. 2022-09-02. Quantum nondemolition measurements with optical parametric amplifiers for ultrafast universal quantum information processing. https://doi.org/10.1103/prxquantum.4.010333

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