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:2307.08394

The success story of squeezed light

Roman Schnabel

Published Jul 17, 2023• 0 citations
arXivHTMLPDF

Abstract

Squeezed states of the optical field were theoretically described in the early 1970s and first observed in the mid 1980s. The measured photon number of a squeezed state is correlated with the measured photon numbers of all other squeezed states of the same ensemble, providing sub-Poissonian statistics. Today all gravitational-wave observatories use squeezed light as the cost-efficient alternative to further scaling up the light power. This user application of quantum correlations was made possible through dedicated research and development of squeezed light between 2002 and 2010.

DOI
10.48550/arxiv.2307.08394

Related papers

SQUEEZED-LIGHT LASERS FOR GRAVITATIONAL WAVE OBSERVATORIES

A. Khalaidovski, H. Vahlbruch, Roman Schnabel

A fundamental noise source limiting the measurement sensitivity of interferometric gravitational wave (GW) observatories is the light's quantum noise. While the sensitivity of the first observatory generation was limited by the shot noise at Fourier frequencies above several hundred hertz, the future observatory generations are expected to be limited by quantum noise also in their low-frequency detection band. Squeezed states of the light field allow for improving the sensitivity at all quantum-noise-limited frequencies. Recently, a squeezing-reduced shot noise of the GW observatory GEO 600 was demonstrated. Based on this success, the Einstein Telescope design study proposes squeezed-light injection to reduce shot noise as well as quantum radiation pressure noise by a factor of ten in power, i.e. by 10 dB. This contribution summarizes the current state of the art in the field of squeezed-light generation for gravitational wave astronomy and the prospects for the intermediate future.

The Ninth Marcel Grossmann Meeting•Jan 29, 2015•0 citations

Gravitational Wave Detection and Squeezed Light

David H. Sliski

Among the revolutionary predictions of Einstein’s theory of general relativity is the existence of gravitational waves, which are perturbations in the fabric of spacetime that travel at the speed of light. The first indirect evidence pointing to their existence came from the observation of the Hulse-Taylor pulsar in 1974[4]. More recently, gravitational wave observatories like the Laser Interferometer Gravitational-wave Observatory (LIGO) and Virgo have been built with the purpose of detecting gravitational waves (GW) directly, providing not only further evidence in support of general relativity, but also a whole new way of viewing the cosmos. The strain produced by a passing gravitational wave (namely, the relative change in the length of the matter a gravitational wave passes through) is so small that the best sensitivity achieved by the detectors has not produced a positive detection as of today. With a clear understanding that there should be gravitational waves, scientists are working on improving the sensitivity of the detectors to increase the likelihood of a detection. One of the main sources of noise for the next generation gravitational wave detectors, such as advanced LIGO, is shot noise. Shot noise dominates the noise spectrum above a few hundred Hz. This noise is due to uncertainties in quantum statistics, according to the generalized uncertainty principle. There are two ways to reduce the shot noise. The first way is to increase the intensity of the

•Jan 1, 2009•0 citations

A gravitational wave detector operating beyond the quantum shot-noise limit: Squeezed light in application

Roman Schnabel

This contribution reviews our recent progress on the generation of squeezed light [1], and also the recent squeezed-light enhancement of the gravitational wave detector GEO 600 [2]. GEO 600 is currently the only GW observatory operated by the LIGO Scientific Collaboration in its search for gravitational waves. With the help of squeezed states of light it now operates with its best ever sensitivity, which not only proves the qualification of squeezed light as a key technology for future gravitational wave astronomy but also the usefulness of quantum entanglement.

EPJ Web of Conferences•Jan 1, 2013•0 citations

The “Squeeze Laser”

Roman Schnabel, Axel Schönbeck

The level of quantum noise in measurements is bounded from below by the Heisenberg uncertainty principle, but it can be unequally distributed between two non-commuting observables — it can be “squeezed”. Since 2019, all gravitational-wave observatories have been using squeezed light for increasing the astronomical reach. Squeezed laser light is efficiently produced by degenerate parametric down-conversion in a nonlinear crystal located inside an optical resonator. A spontaneously generated initial pair of indistinguishable photons is amplified to a squeezed vacuum state. Overlapped with bright coherent light, the photo electric measurement shows a sub-Poissonian photon statistics. Squeezed states have ample applications in nonlocal quantum sensing, device-independent quantum key distribution, and quantum computing. Here, we present our continuous-wave 1550 nm ‘squeeze laser’ with a footprint of 80 cm × 80 cm. The well-defined output beam has an interference contrast of$\gtrsim 99\%$with an overlapped 10 mW beam being in an almost perfect TEM00 mode. The interference result shows 13 dB squeezing of the photon shot noise in balanced detection.

IEEE Transactions on Quantum Engineering•Jan 1, 2022•7 citations

Squeezed vacuum states of light for gravitational wave detectors

L. Barsotti, J. Harms, Roman Schnabel

A century after Einstein's formulation of general relativity, the detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) made the first direct detection of gravitational waves. This historic achievement was the culmination of a world-wide effort and decades of instrument research. While sufficient for this monumental discovery, the current generation of gravitational-wave detectors represent the least sensitive devices necessary for the task; improved detectors will be required to fully exploit this new window on the Universe. In this paper, we review the application of squeezed vacuum states of light to gravitational-wave detectors as a way to reduce quantum noise, which currently limits their performance in much of the detection band.

Reports on Progress in Physics•Mar 23, 2018•139 citations

Squeezed States of Light

Partha Pratim Mondal

Light exists in several distinct quantum states that include photon number and coherent states. But these are not the only states of light, and others that are known to display unusual properties raise hopes for a deeper understanding of the quantum behavior at the classical-quantum barrier. In the previous chapter, we learned about two important states of light: the coherent and number states. In this chapter, we will deal with a special state of light called the squeezed state. As the name suggests, conjugate quantities/variables (such as intensity and phase) can be squeezed beyond their short-noise limit, obeying Heisenberg’s uncertainty principle. These specialized states of light have the distinct ability to measure variables (e.g., intensity) below the short-noise limit. Of course, this comes at the cost of increased uncertainty in the associated conjugate variable. In this chapter, we will explore these possibilities and briefly discuss techniques to generate such light. These specialized light sources find applications in ultrahigh precision measurement (gravitational-wave detection) and sophisticated instrumentation.

•May 25, 2022•0 citations
Squeezed states of the optical field were theoretically described in the early 1970s and first observed in the mid 1980s. The measured photon number of a squeezed state is correlated with the measured photon numbers of all other squeezed states of the same ensemble, providing sub-Poissonian statistics. Today all gravitational-wave observatories use squeezed light as the cost-efficient alternative to further scaling up the light power. This user application of quantum correlations was made possible through dedicated research and development of squeezed light between 2002 and 2010.
A fundamental noise source limiting the measurement sensitivity of interferometric gravitational wave (GW) observatories is the light's quantum noise. While the sensitivity of the first observatory generation was limited by the shot noise at Fourier frequencies above several hundred hertz, the future observatory generations are expected to be limited by quantum noise also in their low-frequency detection band. Squeezed states of the light field allow for improving the sensitivity at all quantum-noise-limited frequencies. Recently, a squeezing-reduced shot noise of the GW observatory GEO 600 was demonstrated. Based on this success, the Einstein Telescope design study proposes squeezed-light injection to reduce shot noise as well as quantum radiation pressure noise by a factor of ten in power, i.e. by 10 dB. This contribution summarizes the current state of the art in the field of squeezed-light generation for gravitational wave astronomy and the prospects for the intermediate future.
Among the revolutionary predictions of Einstein’s theory of general relativity is the existence of gravitational waves, which are perturbations in the fabric of spacetime that travel at the speed of light. The first indirect evidence pointing to their existence came from the observation of the Hulse-Taylor pulsar in 1974[4]. More recently, gravitational wave observatories like the Laser Interferometer Gravitational-wave Observatory (LIGO) and Virgo have been built with the purpose of detecting gravitational waves (GW) directly, providing not only further evidence in support of general relativity, but also a whole new way of viewing the cosmos. The strain produced by a passing gravitational wave (namely, the relative change in the length of the matter a gravitational wave passes through) is so small that the best sensitivity achieved by the detectors has not produced a positive detection as of today. With a clear understanding that there should be gravitational waves, scientists are working on improving the sensitivity of the detectors to increase the likelihood of a detection. One of the main sources of noise for the next generation gravitational wave detectors, such as advanced LIGO, is shot noise. Shot noise dominates the noise spectrum above a few hundred Hz. This noise is due to uncertainties in quantum statistics, according to the generalized uncertainty principle. There are two ways to reduce the shot noise. The first way is to increase the intensity of the
This contribution reviews our recent progress on the generation of squeezed light [1], and also the recent squeezed-light enhancement of the gravitational wave detector GEO 600 [2]. GEO 600 is currently the only GW observatory operated by the LIGO Scientific Collaboration in its search for gravitational waves. With the help of squeezed states of light it now operates with its best ever sensitivity, which not only proves the qualification of squeezed light as a key technology for future gravitational wave astronomy but also the usefulness of quantum entanglement.
The level of quantum noise in measurements is bounded from below by the Heisenberg uncertainty principle, but it can be unequally distributed between two non-commuting observables — it can be “squeezed”. Since 2019, all gravitational-wave observatories have been using squeezed light for increasing the astronomical reach. Squeezed laser light is efficiently produced by degenerate parametric down-conversion in a nonlinear crystal located inside an optical resonator. A spontaneously generated initial pair of indistinguishable photons is amplified to a squeezed vacuum state. Overlapped with bright coherent light, the photo electric measurement shows a sub-Poissonian photon statistics. Squeezed states have ample applications in nonlocal quantum sensing, device-independent quantum key distribution, and quantum computing. Here, we present our continuous-wave 1550 nm ‘squeeze laser’ with a footprint of 80 cm × 80 cm. The well-defined output beam has an interference contrast of≳99%\gtrsim 99\%≳99%with an overlapped 10 mW beam being in an almost perfect TEM00 mode. The interference result shows 13 dB squeezing of the photon shot noise in balanced detection.
A century after Einstein's formulation of general relativity, the detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) made the first direct detection of gravitational waves. This historic achievement was the culmination of a world-wide effort and decades of instrument research. While sufficient for this monumental discovery, the current generation of gravitational-wave detectors represent the least sensitive devices necessary for the task; improved detectors will be required to fully exploit this new window on the Universe. In this paper, we review the application of squeezed vacuum states of light to gravitational-wave detectors as a way to reduce quantum noise, which currently limits their performance in much of the detection band.
Light exists in several distinct quantum states that include photon number and coherent states. But these are not the only states of light, and others that are known to display unusual properties raise hopes for a deeper understanding of the quantum behavior at the classical-quantum barrier. In the previous chapter, we learned about two important states of light: the coherent and number states. In this chapter, we will deal with a special state of light called the squeezed state. As the name suggests, conjugate quantities/variables (such as intensity and phase) can be squeezed beyond their short-noise limit, obeying Heisenberg’s uncertainty principle. These specialized states of light have the distinct ability to measure variables (e.g., intensity) below the short-noise limit. Of course, this comes at the cost of increased uncertainty in the associated conjugate variable. In this chapter, we will explore these possibilities and briefly discuss techniques to generate such light. These specialized light sources find applications in ultrahigh precision measurement (gravitational-wave detection) and sophisticated instrumentation.