Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

New Journal of Physics

Optimal detection of ultra-broadband bi-photons with quantum nonlinear SU(1,1) interference

Nir Nechushtan, Han‐Zhong Zhang, Mallachi-Elia Meller, Avi Pe’er

Published Oct 13, 2021• 5 citations
Publisher

Abstract

The visibility of nonlinear SU(1,1) interference directly reflects the nonclassical properties of entangled bi-photons and squeezed light with practically unlimited bandwidth, high efficiency and ultra-high photon flux, orders of magnitude beyond the abilities of standard photo-detectors. We study experimentally the dependence of the SU(1,1) visibility on the phase matching conditions and beam parameters in a free-space configuration, and show that maximal SU(1,1) visibility requires extreme collinear conditions, which deviate from the conditions for maximal nonlinear conversion. We demonstrate near-ideal visibility of ∼95% (limited only by internal loss) in an ultra-broadband SU(1,1), interferometer with over 120 THz of squeezed light bandwidth. Utilizing this analysis we demonstrate efficient detection of the spectral phase of single-cycle bi-photons and precise compensation of the dispersion over a full octave of bandwidth.

DOI
10.1088/1367-2630/ac2f8f

Related papers

Optimal detection of ultra-broadband bi-photons with quantum nonlinear SU(1,1) interference

Nir Nechushtan, Han‐Zhong Zhang, Mallachi-Elia Meller +1 more

SU(1,1) interference is a major tool for quantum detection of squeezed light. We optimize the interference visibility experimentally based on the phase matching and beam parameters. We demonstrate near-ideal visibility (loss-limited) over an octave bandwidth.

Quantum Information and Measurement (QIM)•Jan 1, 2021•0 citations

A Bi-Photon Quantum Interferometer for Complete Measurement of the Bi-Photon Wave Function

Roey Pomerantz, Yaakov Shaked, Avi Pe’er

We observe at record-high speed the nonclassical nature of ultra-broadband bi-photons, reducing the measurement time by four orders of magnitude compared to standard techniques of Hong-Ou-Mandel interference or sum-frequency generation. We measure the quantum state of the broadband bi-photons, amplitude and phase, with a pairwise Mach-Zehnder quantum interferometer, where bi-photons that are generated in one nonlinear crystal are enhanced (constructive interference) or diminished (destructive interference) in another crystal, depending on the bi-photon phase. We verify the quantum nature of the interference by observing the dependence of the fringe visibility on internal loss. Since destructive interference is equivalent to an attempt to annihilate in the second crystal (by up-conversion) the bi-photons that were created in the first crystal (by down-conversion), the fringe visibility is a measure for the quantum bi-photon purity of the broadband light. The measurement speed-up is due to the large homodyne-like gain from the strong pump ($\!\sim\!10^{7-9}$) in the up-conversion efficiency of single bi-photons, which enables the use of simple photo-detection of the full, ultra-high photon flux instead of single-photon / coincidence counting.

•Sep 19, 2012•0 citations

Observing the nonclassical nature of ultra-broadband bi-photons at ultrafast speed

Yaakov Shaked, Roey Pomerantz, Rafi Z. Vered +1 more

We observe at record-high speed the nonclassical nature of ultra-broadband bi-photons, reducing the measurement time by four orders of magnitude compared to standard techniques of Hong–Ou–Mandel interference or sum-frequency generation. We measure the quantum wave-function of the broadband bi-photons, amplitude and phase, with a pairwise 'Mach–Zehnder' quantum interferometer, where bi-photons that are generated in one nonlinear crystal are enhanced (constructive interference) or diminished (destructive interference) in another crystal, depending on the bi-photon phase. We verify the quantum nature of the interference by observing the dependence of the fringe visibility on internal loss. Since destructive interference is equivalent to an attempt to annihilate in the second crystal (by up-conversion) the bi-photons that were created in the first crystal (by down-conversion), the fringe visibility is a measure of the quantum bi-photon purity of the broadband light. The measurement speed-up is due to the large homodyne-like gain from the strong pump (∼10 7–9 ) in the up-conversion efficiency of single bi-photons, which enables the use of simple photo-detection of the full, ultra-high photon flux instead of single-photon/coincidence counting.

arXiv:1209.4194•New Journal of Physics•May 7, 2014•37 citations

Phase estimation of an SU(1,1) interferometer with superposition of even and odd coherent states

Abdelmajid El Maaroufi, Mouad Ait Maskour, Bouchra Maroufi +1 more

Abstract The SU(1,1) interferometer, a nonlinear analog of the traditional Mach–Zehnder interferometer, has emerged as a powerful tool for achieving phase sensitivity beyond the standard quantum limit. In this work, we propose the use of a superposition of even and odd coherent states as input state to enhance the phase sensitivity of an SU(1,1) interferometer. These non-classical states exhibit unique properties such as squeezing, entanglement, and quantum interference, which can be harnessed to improve metrological precision. Phase sensitivity is analyzed using single-intensity detection and homodyne detection schemes under both ideal and photon loss cases, which demonstrates significant improvements over classical and squeezed-vacuum inputs. In addition, we evaluate the quantum Cramér-Rao lower bound by employing the quantum Fisher information formalism, showing that it surpasses the standard quantum limit and approaches the Heisenberg limit under optimal conditions. Our results highlight the potential of the even and odd coherent states superposition in quantum metrology and provide a pathway for achieving ultra-precise phase measurements in SU(1,1) interferometers for applications in optical sensing, and quantum information processing.

Physica Scripta•Feb 25, 2026•0 citations

Octave-spanning spectral phase control for single-cycle bi-photons

Yaakov Shaked, Shai Yefet, Tzahi Geller +1 more

The quantum correlation of octave-spanning time–energy entangled bi-photons can be as short as a single optical cycle. Many experiments designed to explore and exploit this correlation require a uniform spectral phase (transform-limited) with very low loss. So far, transform-limited single-cycle bi-photons have not been demonstrated, primarily due to the lack of precise, broadband control of their spectral phase. Here, we demonstrate the correction of the spectral-phase of near-octave spanning bi-photons to over an octave in frequency –2600 nm). Using a prism-pair with an effectively negative separation for shaping the bi-photons' spectral phase, we obtain a tuned, very low-loss compensation of both the second and fourth dispersion orders. An essential requisite for precise tuning over such a broad bandwidth is a measure of the spectral phase that provides feedback for the tuning even when the overall dispersion is far from compensated. This is achieved by a non-classical bi-photon interference, which enables direct verification of the corrected bi-photon spectral phase.

arXiv:1403.2193•New Journal of Physics•Jul 15, 2015•8 citations

Bi-Photon Correlation Time Measurements with a Two-Colour Broadband SU(1,1) Interferometer

Franz Roeder, Michael Stefszky, René Pollmann +6 more

We demonstrate spectral and temporal interferometry using a SU(1,1) interferometer based on ultra-broadband, non-degenerate dispersion-engineered parametric down-conversion in nonlinear waveguides. We extract the ultra-short biphoton correlation time and realise dispersion sensitive spectroscopy.

Frontiers in Optics•Jan 1, 2022•2 citations
The visibility of nonlinear SU(1,1) interference directly reflects the nonclassical properties of entangled bi-photons and squeezed light with practically unlimited bandwidth, high efficiency and ultra-high photon flux, orders of magnitude beyond the abilities of standard photo-detectors. We study experimentally the dependence of the SU(1,1) visibility on the phase matching conditions and beam parameters in a free-space configuration, and show that maximal SU(1,1) visibility requires extreme collinear conditions, which deviate from the conditions for maximal nonlinear conversion. We demonstrate near-ideal visibility of ∼95% (limited only by internal loss) in an ultra-broadband SU(1,1), interferometer with over 120 THz of squeezed light bandwidth. Utilizing this analysis we demonstrate efficient detection of the spectral phase of single-cycle bi-photons and precise compensation of the dispersion over a full octave of bandwidth.
We observe at record-high speed the nonclassical nature of ultra-broadband bi-photons, reducing the measurement time by four orders of magnitude compared to standard techniques of Hong-Ou-Mandel interference or sum-frequency generation. We measure the quantum state of the broadband bi-photons, amplitude and phase, with a pairwise Mach-Zehnder quantum interferometer, where bi-photons that are generated in one nonlinear crystal are enhanced (constructive interference) or diminished (destructive interference) in another crystal, depending on the bi-photon phase. We verify the quantum nature of the interference by observing the dependence of the fringe visibility on internal loss. Since destructive interference is equivalent to an attempt to annihilate in the second crystal (by up-conversion) the bi-photons that were created in the first crystal (by down-conversion), the fringe visibility is a measure for the quantum bi-photon purity of the broadband light. The measurement speed-up is due to the large homodyne-like gain from the strong pump ( ⁣∼ ⁣107−9\!\sim\!10^{7-9}∼107−9) in the up-conversion efficiency of single bi-photons, which enables the use of simple photo-detection of the full, ultra-high photon flux instead of single-photon / coincidence counting.
We observe at record-high speed the nonclassical nature of ultra-broadband bi-photons, reducing the measurement time by four orders of magnitude compared to standard techniques of Hong–Ou–Mandel interference or sum-frequency generation. We measure the quantum wave-function of the broadband bi-photons, amplitude and phase, with a pairwise 'Mach–Zehnder' quantum interferometer, where bi-photons that are generated in one nonlinear crystal are enhanced (constructive interference) or diminished (destructive interference) in another crystal, depending on the bi-photon phase. We verify the quantum nature of the interference by observing the dependence of the fringe visibility on internal loss. Since destructive interference is equivalent to an attempt to annihilate in the second crystal (by up-conversion) the bi-photons that were created in the first crystal (by down-conversion), the fringe visibility is a measure of the quantum bi-photon purity of the broadband light. The measurement speed-up is due to the large homodyne-like gain from the strong pump (∼10 7–9 ) in the up-conversion efficiency of single bi-photons, which enables the use of simple photo-detection of the full, ultra-high photon flux instead of single-photon/coincidence counting.
Abstract The SU(1,1) interferometer, a nonlinear analog of the traditional Mach–Zehnder interferometer, has emerged as a powerful tool for achieving phase sensitivity beyond the standard quantum limit. In this work, we propose the use of a superposition of even and odd coherent states as input state to enhance the phase sensitivity of an SU(1,1) interferometer. These non-classical states exhibit unique properties such as squeezing, entanglement, and quantum interference, which can be harnessed to improve metrological precision. Phase sensitivity is analyzed using single-intensity detection and homodyne detection schemes under both ideal and photon loss cases, which demonstrates significant improvements over classical and squeezed-vacuum inputs. In addition, we evaluate the quantum Cramér-Rao lower bound by employing the quantum Fisher information formalism, showing that it surpasses the standard quantum limit and approaches the Heisenberg limit under optimal conditions. Our results highlight the potential of the even and odd coherent states superposition in quantum metrology and provide a pathway for achieving ultra-precise phase measurements in SU(1,1) interferometers for applications in optical sensing, and quantum information processing.
The quantum correlation of octave-spanning time–energy entangled bi-photons can be as short as a single optical cycle. Many experiments designed to explore and exploit this correlation require a uniform spectral phase (transform-limited) with very low loss. So far, transform-limited single-cycle bi-photons have not been demonstrated, primarily due to the lack of precise, broadband control of their spectral phase. Here, we demonstrate the correction of the spectral-phase of near-octave spanning bi-photons to over an octave in frequency –2600 nm). Using a prism-pair with an effectively negative separation for shaping the bi-photons' spectral phase, we obtain a tuned, very low-loss compensation of both the second and fourth dispersion orders. An essential requisite for precise tuning over such a broad bandwidth is a measure of the spectral phase that provides feedback for the tuning even when the overall dispersion is far from compensated. This is achieved by a non-classical bi-photon interference, which enables direct verification of the corrected bi-photon spectral phase.