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

arXiv:2411.11679 · Optica

Strong nanophotonic quantum squeezing exceeding 3.5 dB in a foundry-compatible Kerr microresonator

Yichen Shen, Ping‐Yen Hsieh, Sashank Kaushik Sridhar, Samantha Feldman, You-Chia Chang, Thomas A. Smith, Avik Dutt

Published Jan 30, 2025• 23 citations
arXivHTMLPDF

Abstract

Squeezed light, with its quantum noise reduction capabilities, has emerged as a powerful resource in quantum information processing and precision metrology. To reach noise reduction levels such that a quantum advantage is achieved, off-chip squeezers are typically used. The development of on-chip squeezed light sources, particularly in nanophotonic platforms, has been challenging. We report 3.7±0.2dB of directly detected nanophotonic quantum squeezing using foundry-fabricated silicon nitride (Si 3 N 4 ) microrings with an inferred squeezing level of 10.2 dB on-chip. The squeezing level is robust across multiple devices and pump detunings, and is consistent with the overcoupling degree without noticeable degradation from excess classical noise. We also offer insights to mitigate thermally induced excess noise, which typically degrades squeezing, by using small-radius rings with a larger free spectral range (450 GHz) and consequently lower parametric oscillation thresholds. Our results demonstrate that Si 3 N 4 is a viable platform for strong quantum noise reduction in a CMOS-compatible, scalable architecture.

DOI
10.1364/optica.542968

Related papers

Milliwatt-threshold integrated optical parametric oscillator for broadband quantum squeezing

Zhiming Shi, Xukun Lin, Chaoqian Wei +5 more

Macroscopic bright squeezed light is a crucial continuous-variable quantum resource. However, generating it in integrated Kerr microresonators typically requires strong external overcoupling, which inevitably increases the parametric oscillation threshold and forces a reliance on noisy pump amplifiers. Here, we demonstrate a foundry-compatible silicon nitride ( Si 3 N 4 ) optical parametric oscillator (OPO) that successfully breaks this fundamental trade-off. By leveraging ultralow intrinsic loss alongside a large-free-spectral-range microresonator and a broadband pulley coupler, we achieve a milliwatt-level oscillation threshold with high escape efficiencies across dual telecom bands (C and L). This architecture enables the robust, pump-amplifier-free generation of twin-beam intensity-difference squeezing. We directly observe optical squeezing approaching 3 dB in both bands, with quantum noise reduction extending to analysis frequencies of nearly 100 MHz. Furthermore, our phenomenological model of the power-dependent squeezing dynamics captures the competition among fundamental quantum correlations, detuning-locking jitter, and classical excess noise. Armed with these physical insights and our optimized low-threshold architecture, we successfully bridge the gap between macroscopic quantum squeezing and stringent on-chip power budgets, providing a practical, scalable pathway toward fully monolithic, directly diode-pumped continuous-variable quantum light sources.

Photonics Research•Jul 14, 2026•0 citations

Highly squeezed nanophotonic quantum microcombs with broadband frequency tunability

Yichen Shen, Ping‐Yen Hsieh, Dhruv Srinivasan +8 more

Squeezed light offers genuine quantum advantage in enhanced sensing and quantum computation; yet the level of squeezing or quantum noise reduction generated from nanophotonic chips has been limited. In addition to strong quantum noise reduction, key desiderata for such a nanophotonic squeezer include frequency agility or tunability over a broad frequency range, and simultaneous operation in many distinct, well-defined quantum modes (qumodes). Here we present a strongly overcoupled silicon nitride squeezer based on a below-threshold optical parametric amplifier (OPA) that produces directly detected squeezing of 5.6 dB $\pm$ 0.2 dB, surpassing previous demonstrations in both continuous-wave and pulsed regimes. We introduce a seed-assisted detection technique into such nanophotonic squeezers that reveals a quantum frequency comb (QFC) of 16 qumodes, with a separation of 11~THz between the furthest qumode pair, while maintaining a strong squeezing. Additionally, we report spectral tuning of a qumode comb pair over one free-spectral range of the OPA, thus bridging the spacing between the discrete modes of the QFC. Our results significantly advance both the generation and detection of nanophotonic squeezed light in a broadband and multimode platform, establishing a scalable, chip-integrated path for compact quantum sensors and continuous-variable quantum information processing systems.

arXiv:2505.03734•May 6, 2025•2 citations

Nanophotonic source of broadband quadrature squeezing

Robert Čerňanský, Alberto Politi

Squeezed light are optical beams with variance below the Shot Noise Level. They are a key resource for quantum technologies based on photons, they can be used to achieve better precision measurements, improve security in quantum key distribution channels and as a fundamental resource for quantum computation. To date, the majority of experiments based on squeezed light have been based on non-linear crystals and discrete optical components, as the integration of quadrature squeezed states of light in a nanofabrication-friendly material is a challenging technological task. Here we measure 0.45 dB of GHz-broad quadrature squeezing produced by a ring resonator integrated on a Silicon Nitride photonic chip that we fabricated with CMOS compatible steps. The result corrected for the off-chip losses is estimated to be 1 dB below the Shot Noise Level. We identify and verify that the current results are limited by excess noise produced in the chip, and propose ways to reduce it. Calculations suggest that an improvement in the optical properties of the chip achievable with existing technology can develop scalable quantum technologies based on light.

arXiv:1904.07283•Apr 15, 2019•2 citations

Strong nanophotonic quantum squeezing exceeding 3.5 dB in Kerr microresonator

Yichen Shen, Ping‐Yen Hsieh, Sashank Kaushik Sridhar +4 more

We report the highest level of squeezing directly detected from a microresonator, 3.7 dB (10.7 dB inferred). We use Si3N4 nanophotonic microrings operated in the continuous-wave regime and observe stable squeezing with minimal excess classical noise.

Optical Fiber Communication Conference•Jan 1, 2025•0 citations

Intensity difference squeezing in a strongly overcoupled silicon nitride microresonator

Sara Persia, Yi Sun, V. B. Adya

Integrated nonlinear microring resonators are promising sources of bright twin-beams exhibiting intensity difference squeezing. To take advantage of the noise reduction of these quantum states, many applications require high squeezing levels. However, the attainable on-chip squeezing is constrained by the ratio of intrinsic to coupling loss, which is strongly related to design and fabrication limits. Here, we demonstrate a silicon nitride microring resonator engineered to enable a set of periodic strongly overcoupled resonances from which the estimated on-chip intensity difference squeezing is 11.8 dB, exceptionally high for an integrated device. Due to significant setup loss, we directly measure 1.4±0.2 dB of squeezing, corresponding to an on-chip level of 9.2±5.1 dB. In addition, the new, to the best of our knowledge, design inherently suppresses mode competition in the modes surrounding the twin-beams, enabling a constant high squeezing level up to moderate powers. These results represent a significant step toward the miniaturization of integrated devices whose performance benefits from surpassing the quantum noise limit using squeezed states, with particular relevance to sensing applications.

Optics Letters•Apr 7, 2026•0 citations

Wafer-Scale Squeezed-Light Chips

Shuai Liu, Kailu Zhou, Yuheng Zhang +4 more

Squeezed-light generation in photonic integrated circuits (PICs) is essential for scalable continuous-variable (CV) quantum information processing. By suppressing quantum fluctuations below the shot-noise limit, squeezed states enable quantum-enhanced sensing and serve as a standard resource for CV quantum information processing. While chip-level squeezed-light sources have been demonstrated, extending this capability to the wafer level with reproducible strong squeezing to bolster large-scale quantum-enhanced sensing and information processing has been hindered by squeezed light's extreme susceptibility to device imperfections. Here, we report wafer-scale fabrication, generation, and characterization of two-mode squeezed-vacuum states on a fully complementary metal-oxide-semiconductor (CMOS)-compatible silicon nitride (Si$_3$N$_4$) PIC platform. Across a 4-inch wafer, 8 dies yield 2.9-3.1 dB directly measured quadrature squeezing with $< 0.2$ dB variation, demonstrating excellent uniformity. This performance is enabled by co-integrating ultralow-loss, strongly overcoupled high-$Q$ microresonators, cascaded pump-rejection filters, and low-loss inverse-tapered edge couplers. The measurements agree with a first-principles theoretical model parameterized solely by independently extracted device parameters and experimental settings. The measured squeezing level can be further improved by enhancing the efficiencies of off-chip detection and chip-to-fiber coupling. These results establish a reproducible, wafer-scale route to nonclassical-light generation in integrated photonics and lay the groundwork for scalable CV processors, multiplexed entanglement sources, and quantum-enhanced sensing.

arXiv:2509.10445•Sep 12, 2025•1 citation
Squeezed light, with its quantum noise reduction capabilities, has emerged as a powerful resource in quantum information processing and precision metrology. To reach noise reduction levels such that a quantum advantage is achieved, off-chip squeezers are typically used. The development of on-chip squeezed light sources, particularly in nanophotonic platforms, has been challenging. We report 3.7±0.2dB of directly detected nanophotonic quantum squeezing using foundry-fabricated silicon nitride (Si 3 N 4 ) microrings with an inferred squeezing level of 10.2 dB on-chip. The squeezing level is robust across multiple devices and pump detunings, and is consistent with the overcoupling degree without noticeable degradation from excess classical noise. We also offer insights to mitigate thermally induced excess noise, which typically degrades squeezing, by using small-radius rings with a larger free spectral range (450 GHz) and consequently lower parametric oscillation thresholds. Our results demonstrate that Si 3 N 4 is a viable platform for strong quantum noise reduction in a CMOS-compatible, scalable architecture.
Macroscopic bright squeezed light is a crucial continuous-variable quantum resource. However, generating it in integrated Kerr microresonators typically requires strong external overcoupling, which inevitably increases the parametric oscillation threshold and forces a reliance on noisy pump amplifiers. Here, we demonstrate a foundry-compatible silicon nitride ( Si 3 N 4 ) optical parametric oscillator (OPO) that successfully breaks this fundamental trade-off. By leveraging ultralow intrinsic loss alongside a large-free-spectral-range microresonator and a broadband pulley coupler, we achieve a milliwatt-level oscillation threshold with high escape efficiencies across dual telecom bands (C and L). This architecture enables the robust, pump-amplifier-free generation of twin-beam intensity-difference squeezing. We directly observe optical squeezing approaching 3 dB in both bands, with quantum noise reduction extending to analysis frequencies of nearly 100 MHz. Furthermore, our phenomenological model of the power-dependent squeezing dynamics captures the competition among fundamental quantum correlations, detuning-locking jitter, and classical excess noise. Armed with these physical insights and our optimized low-threshold architecture, we successfully bridge the gap between macroscopic quantum squeezing and stringent on-chip power budgets, providing a practical, scalable pathway toward fully monolithic, directly diode-pumped continuous-variable quantum light sources.
Squeezed light offers genuine quantum advantage in enhanced sensing and quantum computation; yet the level of squeezing or quantum noise reduction generated from nanophotonic chips has been limited. In addition to strong quantum noise reduction, key desiderata for such a nanophotonic squeezer include frequency agility or tunability over a broad frequency range, and simultaneous operation in many distinct, well-defined quantum modes (qumodes). Here we present a strongly overcoupled silicon nitride squeezer based on a below-threshold optical parametric amplifier (OPA) that produces directly detected squeezing of 5.6 dB ±\pm± 0.2 dB, surpassing previous demonstrations in both continuous-wave and pulsed regimes. We introduce a seed-assisted detection technique into such nanophotonic squeezers that reveals a quantum frequency comb (QFC) of 16 qumodes, with a separation of 11~THz between the furthest qumode pair, while maintaining a strong squeezing. Additionally, we report spectral tuning of a qumode comb pair over one free-spectral range of the OPA, thus bridging the spacing between the discrete modes of the QFC. Our results significantly advance both the generation and detection of nanophotonic squeezed light in a broadband and multimode platform, establishing a scalable, chip-integrated path for compact quantum sensors and continuous-variable quantum information processing systems.
Squeezed light are optical beams with variance below the Shot Noise Level. They are a key resource for quantum technologies based on photons, they can be used to achieve better precision measurements, improve security in quantum key distribution channels and as a fundamental resource for quantum computation. To date, the majority of experiments based on squeezed light have been based on non-linear crystals and discrete optical components, as the integration of quadrature squeezed states of light in a nanofabrication-friendly material is a challenging technological task. Here we measure 0.45 dB of GHz-broad quadrature squeezing produced by a ring resonator integrated on a Silicon Nitride photonic chip that we fabricated with CMOS compatible steps. The result corrected for the off-chip losses is estimated to be 1 dB below the Shot Noise Level. We identify and verify that the current results are limited by excess noise produced in the chip, and propose ways to reduce it. Calculations suggest that an improvement in the optical properties of the chip achievable with existing technology can develop scalable quantum technologies based on light.
Integrated nonlinear microring resonators are promising sources of bright twin-beams exhibiting intensity difference squeezing. To take advantage of the noise reduction of these quantum states, many applications require high squeezing levels. However, the attainable on-chip squeezing is constrained by the ratio of intrinsic to coupling loss, which is strongly related to design and fabrication limits. Here, we demonstrate a silicon nitride microring resonator engineered to enable a set of periodic strongly overcoupled resonances from which the estimated on-chip intensity difference squeezing is 11.8 dB, exceptionally high for an integrated device. Due to significant setup loss, we directly measure 1.4±0.2 dB of squeezing, corresponding to an on-chip level of 9.2±5.1 dB. In addition, the new, to the best of our knowledge, design inherently suppresses mode competition in the modes surrounding the twin-beams, enabling a constant high squeezing level up to moderate powers. These results represent a significant step toward the miniaturization of integrated devices whose performance benefits from surpassing the quantum noise limit using squeezed states, with particular relevance to sensing applications.
Squeezed-light generation in photonic integrated circuits (PICs) is essential for scalable continuous-variable (CV) quantum information processing. By suppressing quantum fluctuations below the shot-noise limit, squeezed states enable quantum-enhanced sensing and serve as a standard resource for CV quantum information processing. While chip-level squeezed-light sources have been demonstrated, extending this capability to the wafer level with reproducible strong squeezing to bolster large-scale quantum-enhanced sensing and information processing has been hindered by squeezed light's extreme susceptibility to device imperfections. Here, we report wafer-scale fabrication, generation, and characterization of two-mode squeezed-vacuum states on a fully complementary metal-oxide-semiconductor (CMOS)-compatible silicon nitride (Si3_33​N4_44​) PIC platform. Across a 4-inch wafer, 8 dies yield 2.9-3.1 dB directly measured quadrature squeezing with <0.2< 0.2<0.2 dB variation, demonstrating excellent uniformity. This performance is enabled by co-integrating ultralow-loss, strongly overcoupled high-QQQ microresonators, cascaded pump-rejection filters, and low-loss inverse-tapered edge couplers. The measurements agree with a first-principles theoretical model parameterized solely by independently extracted device parameters and experimental settings. The measured squeezing level can be further improved by enhancing the efficiencies of off-chip detection and chip-to-fiber coupling. These results establish a reproducible, wafer-scale route to nonclassical-light generation in integrated photonics and lay the groundwork for scalable CV processors, multiplexed entanglement sources, and quantum-enhanced sensing.