Noise model for a dual frequency comb beat

We demonstrate a simple and robust technique for improving the signal-to-noise ratio (SNR) of heterodyne beats between a low-power frequency comb and a continuous-wave (cw) laser. By exploiting the pulsed nature of the comb, a SNR better than the shot-noise limit for the beating of a single mode can be obtained. This technique relies on electrical gating of the beat signal to remove as much shot noise as possible from the measurement. This technique can also be understood as efficiently using the beating of the cw laser with many comb modes simultaneously. We demonstrate a simple experimental setup which achieves a 50-fold improvement in the shot-noise limited SNR of a conventional heterodyne setup and is in long-term agreement with a conventional heterodyne setup, at least to better than 1 part in ${10}^{17}$ . The resulting analog signal is completely compatible with existing heterodyne setups and can be used as an upgrade to an existing setup which would benefit from the SNR improvement.We demonstrate a simple and robust technique for improving the signal-to-noise ratio (SNR) of heterodyne beats between a low-power frequency comb and a continuous-wave (cw) laser. By exploiting the pulsed nature of the comb, a SNR better than the shot-noise limit for the beating of a single mode can be obtained. This technique relies on electrical gating of the beat signal to remove as much shot noise as possible from the measurement. This technique can also be understood as efficiently using the beating of the cw laser with many comb modes simultaneously. We demonstrate a simple experimental setup which achieves a 50-fold improvement in the shot-noise limited SNR of a conventional heterodyne setup and is in long-term agreement with a conventional heterodyne setup, at least to better than 1 part in ${10}^{17}$. The resulting analog signal is completely compatible with existing heterodyne setups and can be used as an upgrade to an existing setup which would benefit from the SNR improvement.

Physical Review AFeb 4, 201330 citations

Modeling Low-Frequency Hamiltonian Noise

Corey Ostrove, Megan Dahlhauser, Timothy J Proctor +2 more

APS March Meeting AbstractsMar 1, 20230 citations

Stochastic Simulation of Noise

Thomas Grurl, Jürgen Fuß, Robert Wille

Synthesis lectures on engineering, science, and technologyNov 29, 20240 citations

Enhanced multichannel dual-comb spectroscopy of complex systems

Razmik Aramyan, Oleg Tretiak, Sushree S. Sahoo +1 more

A multichannel dual-comb spectroscopy (DCS) approach for high-resolution, broadband spectral measurements is presented, demonstrating its effectiveness in studying complex atomic systems. By implementing a photodetector array, we enhance DCS capabilities, addressing the fundamental trade-off between signal-to-noise ratio and spectral coverage. To resolve ambiguities in frequency conversion, we introduced a relative offset in beat-note frequency, ensuring accurate spectral reconstruction. As a proof of concept, the absorption spectrum of samarium ( Sm ) vapor is investigated over a 52-nm range, and several previously unreported absorption lines are detected. This is a step toward “Spectroscopy 2.0,” enabling massively parallel spectroscopic measurements (including those at > 100 T magnetic fields) crucial for atomic physics and fundamental interactions research.A multichannel dual-comb spectroscopy (DCS) approach for high-resolution, broadband spectral measurements is presented, demonstrating its effectiveness in studying complex atomic systems. By implementing a photodetector array, we enhance DCS capabilities, addressing the fundamental trade-off between signal-to-noise ratio and spectral coverage. To resolve ambiguities in frequency conversion, we introduced a relative offset in beat-note frequency, ensuring accurate spectral reconstruction. As a proof of concept, the absorption spectrum of samarium ( Sm ) vapor is investigated over a 52-nm range, and several previously unreported absorption lines are detected. This is a step toward “Spectroscopy 2.0,” enabling massively parallel spectroscopic measurements (including those at > 100 T magnetic fields) crucial for atomic physics and fundamental interactions research.

arXiv:2502.14126Physical Review AppliedJul 16, 20251 citation

Sub-Shot-Noise FM Noise Spectroscopy

Jungsang Kim, Seema Somani, Y. Yamamoto

Springer series in photonicsJan 1, 20010 citations

Dual frequency calibration to build a portable vapor cell optical clock with improved stability and without a frequency comb

Sreeshna Subhash, Greeshma Gopinath, Sankar Davuluri

This article theoretically proposes a new dual interferometer technique to accurately calibrate two laser frequencies simultaneously using four-wave mixing in an alkali metal vapor cell. The two frequency-calibrated lasers are mixed to create a beat signal at radio frequency to build a portable optical atomic clock (OAC) without an optical frequency comb (OFC). Removal of the OFC improves the portability of OAC, while the dual interferometer setup enhances the one second stability to $1.3\times 10^{-15}$ , which is better than the current portable OAC. Thermal noise in the OAC is minimized by choosing the double-lambda atomic scheme with co-propagating laser fields. Using D2 transition of Rb-87, the standard quantum limited frequency sensitivity and stability of the OAC are estimated as $3.2\;\sqrt{\mbox{Hz}}$, and $1.3\times10^{-15}\sqrt{\mbox{Hz}^{-1}}$, respectively. After considering broadening effects due to $357\,$ K temperature and collisions, the optimum stability of the OAC is reduced to $3.3\times10^{-15}\sqrt{\mbox{Hz}^{-1}}$ for a laser with $1\,$ KHz linewidth and $0.54$ mW power at the input of the vapor cell.This article theoretically proposes a new dual interferometer technique to accurately calibrate two laser frequencies simultaneously using four-wave mixing in an alkali metal vapor cell. The two frequency-calibrated lasers are mixed to create a beat signal at radio frequency to build a portable optical atomic clock (OAC) without an optical frequency comb (OFC). Removal of the OFC improves the portability of OAC, while the dual interferometer setup enhances the one second stability to $1.3\times 10^{-15}$, which is better than the current portable OAC. Thermal noise in the OAC is minimized by choosing the double-lambda atomic scheme with co-propagating laser fields. Using D2 transition of Rb-87, the standard quantum limited frequency sensitivity and stability of the OAC are estimated as $3.2\;\sqrt{\mbox{Hz}}$, and $1.3\times10^{-15}\sqrt{\mbox{Hz}^{-1}}$, respectively. After considering broadening effects due to $357\,$K temperature and collisions, the optimum stability of the OAC is reduced to $3.3\times10^{-15}\sqrt{\mbox{Hz}^{-1}}$ for a laser with $1\,$KHz linewidth and $0.54$ mW power at the input of the vapor cell.

arXiv:2507.04911Jul 7, 20250 citations

{10}^{17}

. The resulting analog signal is completely compatible with existing heterodyne setups and can be used as an upgrade to an existing setup which would benefit from the SNR improvement.

1.3\times 10^{-15}

, which is better than the current portable OAC. Thermal noise in the OAC is minimized by choosing the double-lambda atomic scheme with co-propagating laser fields. Using D2 transition of Rb-87, the standard quantum limited frequency sensitivity and stability of the OAC are estimated as $3.2\;\sqrt{\mbox{Hz}}$, and $1.3\times10^{-15}\sqrt{\mbox{Hz}^{-1}}$, respectively. After considering broadening effects due to

357\,

K temperature and collisions, the optimum stability of the OAC is reduced to $3.3\times10^{-15}\sqrt{\mbox{Hz}^{-1}}$ for a laser with

1\,

KHz linewidth and

0.54

mW power at the input of the vapor cell.