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

Optics Express

Noiseless electro-optic processing of optical signals generated with squeezed light

Ping Koy Lam, Timothy C. Ralph, Elanor H. Huntington, David E. McClelland, Hans‐A. Bachor

Published Feb 2, 1998• 1 citation
Publisher

Abstract

We demonstrate an elegant way of handling optical signals which are generated using squeezed states of light without losing their improved signal to noise ratio. We do this by amplifing, without significant noise penalty, both signal and noise away from the quantum noise limit into the classical domain. This makes the information robust to losses. Our system achieves a signal transfer coefficient, T(s), close to unity. As a demonstration we amplify a small signal carried by 35% amplitude squeezed light and show that unlike the fragile squeezed input, the signal amplified output is robust to propagation losses. A signal transfer coefficient of T(s) = 0.75 is achieved even in the presence of large introduced (86%) downstream losses.

DOI
10.1364/oe.2.000100

Related papers

Noiseless Signal Amplification using Positive Electro-Optic Feedforward

Ping Koy Lam, Timothy C. Ralph, Elanor H. Huntington +1 more

We propose an electro-optic feedforward scheme which can in principle produce perfect noiseless signal amplification (signal transfer coefficient of ${T}_{\mathrm{s}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1$). We demonstrate the scheme experimentally and report, for a signal gain of 13.4 dB, a signal transfer coefficient of ${T}_{\mathrm{s}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.88$ which is limited mainly by detector efficiencies (92%). The result clearly exceeds the standard quantum limit, ${T}_{\mathrm{s}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.5$, set by the high gain limit of a phase insensitive linear amplifier. We use the scheme to amplify a small signal carried by 35% amplitude squeezed light and demonstrate that, unlike the fragile squeezed input, the signal amplified output is robust to propagation losses.

Physical Review Letters•Aug 25, 1997•64 citations

Robust transmission and reconstruction of fragile optical states

Timothy C. Ralph

We propose a scheme by which signals carried by a coherent optical source close to the quantum noise limit can be amplified, making them more robust against losses, and then reconstructed at a remote site. The amplitude signal-to-noise ratio, the absolute amplitude noise level, and optical coherence are preserved. The scheme utilizes electro-optic feedforward and laser injection locking. We investigate the performance of the scheme as a quantum nondemolition device.

Physical Review A•Nov 1, 1997•10 citations

Overcoming detection loss and noise in squeezing-based optical sensing

Gaetano Frascella, Sascha Agne, Farid Ya. Khalili +1 more

Abstract Among the known resources of quantum metrology, one of the most practical and efficient is squeezing. Squeezed states of atoms and light improve the sensing of the phase, magnetic field, polarization, mechanical displacement. They promise to considerably increase signal-to-noise ratio in imaging and spectroscopy, and are already used in real-life gravitational-wave detectors. But despite being more robust than other states, they are still very fragile, which narrows the scope of their application. In particular, squeezed states are useless in measurements where the detection is inefficient or the noise is high. Here, we experimentally demonstrate a remedy against loss and noise: strong noiseless amplification before detection. This way, we achieve loss-tolerant operation of an interferometer fed with squeezed and coherent light. With only 50% detection efficiency and with noise exceeding the level of squeezed light more than 50 times, we overcome the shot-noise limit by 6 dB. Sub-shot-noise phase sensitivity survives up to 87% loss. Application of this technique to other types of optical sensing and imaging promises a full use of quantum resources in these fields.

arXiv:2005.08843•npj Quantum Information•May 12, 2021•68 citations

Loss-tolerant interferometry with squeezed light

Maria V. Chekhova, Gaetano Frascella, Sascha Agne +1 more

An important part of optical sensing is interferometry, where direct or homodyne detection at the output of an interferometer yields information about small phase shifts. Classical interferometry operates at the shot-noise limit (SNL), caused by the photon structure of light and reached when an interferometer is fed with coherent light. The use of nonclassical light at the input of an interferometer enables overcoming the SNL. In particular, squeezed light is known to be less noisy than coherent light. An interferometer fed with strongly squeezed light can, in principle, provide the phase sensitivity at the Heisenberg limit, the ultimate limit allowed by the laws of physics. However, this supersensitive operation is strongly degraded by loss – both inside the interferometer and outside it, at the stage of detection. While the former (internal loss) seems to be inevitable, the latter (detection loss) can be overcome, and we demonstrate it in our recent experiment. The clue is to amplify light at the interferometer output using a phase-sensitive optical parametric amplifier. This device does not introduce additional noise, but it amplifies the fragile quantum signal and thus makes it tolerant to loss at the detection stage. In a proof-of-principle experiment, we build a polarization Mach-Zehnder interferometer and feed it with coherent light in one port and a squeezed vacuum in another port. At one output port, we amplify light with an optical parametric amplifier and measure a phase sensitivity of 13 mrad for 1500 photons in the interferometer. This result, achieved with 50% detection efficiency, overcomes the SNL by 3 dB. Moreover, by using stronger amplification, we can overcome the SNL under detection efficiency as low as 13%. Our results outline a way to use squeezed light for real-life sensing, where the detection efficiency cannot be very high, especially in spectral ranges like middle-infrared or terahertz.

Emerging Imaging and Sensing Technologies for Security and Defence; and Advanced Manufacturing Technologies for Micro- and Nanosystems in Security and Defence•Sep 18, 2020•0 citations

Use of the squeezed (sub-Poisson) state of light in small-signal detection with preamplification upon four-wave mixing

A. V. Kozlovskiĭ

The scheme of an active interferometer for amplification of small optical signals for their subsequent photodetection is proposed. The scheme provides a considerable amplification of signals by preserving their quantum-statistical properties (ideal amplification) and also can improve these properties under certain conditions. The two-mode squeezed state of light produced upon four-wave mixing, which is used for signal amplification, can be transformed to the non-classical state of the output field squeezed in the number of photons. The scheme is phase-sensitive upon amplification of the input coherent signal. It is shown that in the case of the incoherent input signal with the average number of photons ⟨ n s ⟩∼1, the amplification process introduces no additional quantum noise at signal amplification as large as is wished. A scheme is also proposed for the cascade small-signal amplification (⟨ n s ⟩∼1) in the coherent state producing the amplified signal in the squeezed sub-Poisson state, which can be used for the high-resolution detection of weak and ultraweak optical signals.

Quantum Electronics•Jan 31, 2007•2 citations

Squeezed amplification in a gain-saturated parametric amplifier

N. C. Wong, Ke-Xun Sun, Jeffrey H. Shapiro

Recently optical parametric amplifiers (OPAs) with vacuum inputs have been extensively studied and shown to generate a significant amount of squeezing, but little is known about the quantum noise behavior of an OPA with an injected signal field. We have performed a linearized quantum analysis of a nondegenerate OPA operated in the saturated gain regime showing that the amplified output intensity of a coherent-state input signal becomes squeezed when the classical small-signal gain falls below unity. In uses such as master-oscillator power amplifiers, for which the signal of interest is the mean output intensity, the output signal-to-noise ratio (SNR) can be higher than the input SNR over a broad operating range. For an OPA pumped at 90% of threshold, the SNR improvement is about a factor of 3, and with a 10-Db amplitude squeezed pump, the improvement increases to about a factor of 7. Such a tunable gain-saturated OPA with large-signal gain and improved SNR can be potentially useful in digital communication.

Annual Meeting Optical Society of America•Jan 1, 1991•0 citations
We demonstrate an elegant way of handling optical signals which are generated using squeezed states of light without losing their improved signal to noise ratio. We do this by amplifing, without significant noise penalty, both signal and noise away from the quantum noise limit into the classical domain. This makes the information robust to losses. Our system achieves a signal transfer coefficient, T(s), close to unity. As a demonstration we amplify a small signal carried by 35% amplitude squeezed light and show that unlike the fragile squeezed input, the signal amplified output is robust to propagation losses. A signal transfer coefficient of T(s) = 0.75 is achieved even in the presence of large introduced (86%) downstream losses.
We propose an electro-optic feedforward scheme which can in principle produce perfect noiseless signal amplification (signal transfer coefficient of Ts=1{T}_{\mathrm{s}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1Ts​=1). We demonstrate the scheme experimentally and report, for a signal gain of 13.4 dB, a signal transfer coefficient of Ts=0.88{T}_{\mathrm{s}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.88Ts​=0.88 which is limited mainly by detector efficiencies (92%). The result clearly exceeds the standard quantum limit, Ts=0.5{T}_{\mathrm{s}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.5Ts​=0.5, set by the high gain limit of a phase insensitive linear amplifier. We use the scheme to amplify a small signal carried by 35% amplitude squeezed light and demonstrate that, unlike the fragile squeezed input, the signal amplified output is robust to propagation losses.
Abstract Among the known resources of quantum metrology, one of the most practical and efficient is squeezing. Squeezed states of atoms and light improve the sensing of the phase, magnetic field, polarization, mechanical displacement. They promise to considerably increase signal-to-noise ratio in imaging and spectroscopy, and are already used in real-life gravitational-wave detectors. But despite being more robust than other states, they are still very fragile, which narrows the scope of their application. In particular, squeezed states are useless in measurements where the detection is inefficient or the noise is high. Here, we experimentally demonstrate a remedy against loss and noise: strong noiseless amplification before detection. This way, we achieve loss-tolerant operation of an interferometer fed with squeezed and coherent light. With only 50% detection efficiency and with noise exceeding the level of squeezed light more than 50 times, we overcome the shot-noise limit by 6 dB. Sub-shot-noise phase sensitivity survives up to 87% loss. Application of this technique to other types of optical sensing and imaging promises a full use of quantum resources in these fields.
An important part of optical sensing is interferometry, where direct or homodyne detection at the output of an interferometer yields information about small phase shifts. Classical interferometry operates at the shot-noise limit (SNL), caused by the photon structure of light and reached when an interferometer is fed with coherent light. The use of nonclassical light at the input of an interferometer enables overcoming the SNL. In particular, squeezed light is known to be less noisy than coherent light. An interferometer fed with strongly squeezed light can, in principle, provide the phase sensitivity at the Heisenberg limit, the ultimate limit allowed by the laws of physics. However, this supersensitive operation is strongly degraded by loss – both inside the interferometer and outside it, at the stage of detection. While the former (internal loss) seems to be inevitable, the latter (detection loss) can be overcome, and we demonstrate it in our recent experiment. The clue is to amplify light at the interferometer output using a phase-sensitive optical parametric amplifier. This device does not introduce additional noise, but it amplifies the fragile quantum signal and thus makes it tolerant to loss at the detection stage. In a proof-of-principle experiment, we build a polarization Mach-Zehnder interferometer and feed it with coherent light in one port and a squeezed vacuum in another port. At one output port, we amplify light with an optical parametric amplifier and measure a phase sensitivity of 13 mrad for 1500 photons in the interferometer. This result, achieved with 50% detection efficiency, overcomes the SNL by 3 dB. Moreover, by using stronger amplification, we can overcome the SNL under detection efficiency as low as 13%. Our results outline a way to use squeezed light for real-life sensing, where the detection efficiency cannot be very high, especially in spectral ranges like middle-infrared or terahertz.
The scheme of an active interferometer for amplification of small optical signals for their subsequent photodetection is proposed. The scheme provides a considerable amplification of signals by preserving their quantum-statistical properties (ideal amplification) and also can improve these properties under certain conditions. The two-mode squeezed state of light produced upon four-wave mixing, which is used for signal amplification, can be transformed to the non-classical state of the output field squeezed in the number of photons. The scheme is phase-sensitive upon amplification of the input coherent signal. It is shown that in the case of the incoherent input signal with the average number of photons ⟨ n s ⟩∼1, the amplification process introduces no additional quantum noise at signal amplification as large as is wished. A scheme is also proposed for the cascade small-signal amplification (⟨ n s ⟩∼1) in the coherent state producing the amplified signal in the squeezed sub-Poisson state, which can be used for the high-resolution detection of weak and ultraweak optical signals.
Recently optical parametric amplifiers (OPAs) with vacuum inputs have been extensively studied and shown to generate a significant amount of squeezing, but little is known about the quantum noise behavior of an OPA with an injected signal field. We have performed a linearized quantum analysis of a nondegenerate OPA operated in the saturated gain regime showing that the amplified output intensity of a coherent-state input signal becomes squeezed when the classical small-signal gain falls below unity. In uses such as master-oscillator power amplifiers, for which the signal of interest is the mean output intensity, the output signal-to-noise ratio (SNR) can be higher than the input SNR over a broad operating range. For an OPA pumped at 90% of threshold, the SNR improvement is about a factor of 3, and with a 10-Db amplitude squeezed pump, the improvement increases to about a factor of 7. Such a tunable gain-saturated OPA with large-signal gain and improved SNR can be potentially useful in digital communication.