Quantified convergence of general homodyne measurements with applications to continuous variable quantum computing

Fuente: arXiv
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Autores principales: Knill, Emanuel, Shojaee, Ezad, van Meter, James R., Kyle, Akira, Glancy, Scott
Formato: Preprint
Publicado: 2026
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author Knill, Emanuel
Shojaee, Ezad
van Meter, James R.
Kyle, Akira
Glancy, Scott
author_facet Knill, Emanuel
Shojaee, Ezad
van Meter, James R.
Kyle, Akira
Glancy, Scott
contents In arXiv:2503.00188 we introduced broadband pulsed (BBP) homodyne measurements as a generalization of standard pulsed homodyne quadrature measurements. BBP can take advantage of detectors such as calorimeters that have the potential for high efficiency over a broad spectral range. BBP homodyne retains the advantages of standard pulsed homodyne, enabling measurement of arbitrary quadratures in the limit of large amplitude local oscillators (LO). Here we quantify the convergence of standard and BBP homodyne quadrature measurements to those of the quadrature of interest. We obtain lower bounds on the fidelity of the post-measurement classical-quantum state of outcomes and unmeasured modes, and the fidelity of the states obtained after applying operations conditional on measurement outcomes. The bounds depend on the LO amplitude and the moments of number operators. We demonstrate the practical relevance of these bounds by evaluating them for standard pulsed homodyne used for estimating values of the characteristic function of the Wigner distribution, expectations of moments, for quantum teleportation and for continuous variable error correction with GKP codes.
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id arxiv_https___arxiv_org_abs_2602_22511
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Quantified convergence of general homodyne measurements with applications to continuous variable quantum computing
Knill, Emanuel
Shojaee, Ezad
van Meter, James R.
Kyle, Akira
Glancy, Scott
Quantum Physics
In arXiv:2503.00188 we introduced broadband pulsed (BBP) homodyne measurements as a generalization of standard pulsed homodyne quadrature measurements. BBP can take advantage of detectors such as calorimeters that have the potential for high efficiency over a broad spectral range. BBP homodyne retains the advantages of standard pulsed homodyne, enabling measurement of arbitrary quadratures in the limit of large amplitude local oscillators (LO). Here we quantify the convergence of standard and BBP homodyne quadrature measurements to those of the quadrature of interest. We obtain lower bounds on the fidelity of the post-measurement classical-quantum state of outcomes and unmeasured modes, and the fidelity of the states obtained after applying operations conditional on measurement outcomes. The bounds depend on the LO amplitude and the moments of number operators. We demonstrate the practical relevance of these bounds by evaluating them for standard pulsed homodyne used for estimating values of the characteristic function of the Wigner distribution, expectations of moments, for quantum teleportation and for continuous variable error correction with GKP codes.
title Quantified convergence of general homodyne measurements with applications to continuous variable quantum computing
topic Quantum Physics
url https://arxiv.org/abs/2602.22511