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

Physical Review A

Squeezing more from a quantum nondemolition measurement

B. C. Buchler, Ping Koy Lam, Hans‐A. Bachor, Ulrik L. Andersen, Timothy C. Ralph

Published Dec 13, 2001• 28 citations
Publisher

Abstract

We use a stable, 5 dB, amplitude squeezed source for a quantum nondemolition (QND) experiment. The performance of our QND system is enhanced by an electro-optic feedforward loop which improves the signal transfer efficiency. At best, we measure a total signal transfer of 1.81 and conditional variance of 0.55.
DOI
10.1103/physreva.65.011803

Related papers

Enhancing Quantum Nondemolition Measurements using Electro-Optic Feedforward

Ulrik L. Andersen, B. C. Buchler, Ping Koy Lam +2 more

Quantum Nondemolition (QND) measurements are carried out using a stable amplitude squeezed beam. The performance of the QND measurement is substantially enhanced by an electro-optic feedforward loop, which improves the signal transfer efficiency.

Optical Fiber Communication Conference•Jan 1, 2001•0 citations

Quantum nondemolition measurement with a nonclassical meter input and an electro-optic enhancement

Ulrik L. Andersen, B. C. Buchler, Hans‐A. Bachor +1 more

Optical quantum nondemolition measurements are performed using a beamsplitter with a nonclassical meter input and a electro-optic feedforward loop. The nonclassical meter input is provided by a stable 4.5 dB amplitude squeezed source generated by an optical parametric amplifier. We show that the implementation of a feedforward loop gives a substantial improvement in the signal transfer efficiency. With a 92% reflective beamsplitter we measure a transfer coefficient of Ts+m = 1.81. The quantum state preparation ability of our system is evaluated using two-dimensional correlation plots. This technique allows the direct visualization of the quantum correlations between the outputs of the QND system.

Journal of Optics B Quantum and Semiclassical Optics•Apr 5, 2002•8 citations

Enhancement of quantum nondemolition measurements with an electro-optic feed-forward amplifier

B. C. Buchler, Ping Koy Lam, Timothy C. Ralph

Methods for the enhancement of optical quantum nondemolition (QND) measurements are discussed. We review the use of meter squeezing as a QND enhancement tool and present a method of QND enhancement using an electro-optic feed-forward amplifier. By applying a linearized theory it is shown that these techniques work very well together. The combined effect of these enhancement methods is modeled for two QND systems, a squeezed light beam splitter and an optical parametric amplifier. We also discuss the conflict between the normal QND criteria and QND systems that involve noiseless amplification. We use an additional parameter to quantify the problem. A method for correcting the effects of noiseless amplification is discussed and modeled. We also discuss a special case of QND that eliminates the optical interaction between the meter and signal input beams. This system is shown to be a very effective QND device.

Physical Review A•Dec 1, 1999•13 citations

Quantum Nondemolition Measurements Improved by a Squeezed Meter Input

Robert Bruckmeier, Klaus Schneider, Stephan Schiller +1 more

Continuous quantum nondemolition (QND) measurements of the amplitude quadrature of a 1064 nm wave are performed with a monolithic dual-port degenerate optical parametric amplifier (OPA). The quality of the measurement is limited in part by the quantum fluctuations carried by the vacuum meter input wave. Improved QND measurements are realized by injecting 3.4 dB amplitude-squeezed light into the meter input port of the OPA. This achieves increased squeezing and correlation of the output signal and meter waves, and both improved operation as a quantum optical tap and as a quantum state preparator. The all-solid-state system was operated for 5 h with high stability.

Physical Review Letters•Feb 17, 1997•35 citations

Quantum nondemolition measurements and generation of individually squeezed twin beams by a degenerate optical parametric amplifier

Stephan Schiller, Robert Bruckmeier, Manfred Schalke +2 more

A novel scheme for continuous-wave quantum nondemolition (QND) detection of optical-amplitude quadratures is implemented using a degenerate optical parametric amplifier. A monolithic ring resonator with optimizable frustrated total internal reflection coupling is used. Signal and meter output beams are squeezed by 0.5 dB and 2.2 dB, and 38% correlated. This implies the first realization of individually squeezed twin beams, as well as quantum state preparation ability for both output beams. A quantum optical tap efficiency T s + T m = 1.08 is achieved. The all-solid-state system was completely stabilized and continuously operated as a QND device for up to 36 hours.

Europhysics Letters (EPL)•Nov 10, 1996•16 citations

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
Optical quantum nondemolition measurements are performed using a beamsplitter with a nonclassical meter input and a electro-optic feedforward loop. The nonclassical meter input is provided by a stable 4.5 dB amplitude squeezed source generated by an optical parametric amplifier. We show that the implementation of a feedforward loop gives a substantial improvement in the signal transfer efficiency. With a 92% reflective beamsplitter we measure a transfer coefficient of Ts+m = 1.81. The quantum state preparation ability of our system is evaluated using two-dimensional correlation plots. This technique allows the direct visualization of the quantum correlations between the outputs of the QND system.
Methods for the enhancement of optical quantum nondemolition (QND) measurements are discussed. We review the use of meter squeezing as a QND enhancement tool and present a method of QND enhancement using an electro-optic feed-forward amplifier. By applying a linearized theory it is shown that these techniques work very well together. The combined effect of these enhancement methods is modeled for two QND systems, a squeezed light beam splitter and an optical parametric amplifier. We also discuss the conflict between the normal QND criteria and QND systems that involve noiseless amplification. We use an additional parameter to quantify the problem. A method for correcting the effects of noiseless amplification is discussed and modeled. We also discuss a special case of QND that eliminates the optical interaction between the meter and signal input beams. This system is shown to be a very effective QND device.
Continuous quantum nondemolition (QND) measurements of the amplitude quadrature of a 1064 nm wave are performed with a monolithic dual-port degenerate optical parametric amplifier (OPA). The quality of the measurement is limited in part by the quantum fluctuations carried by the vacuum meter input wave. Improved QND measurements are realized by injecting 3.4 dB amplitude-squeezed light into the meter input port of the OPA. This achieves increased squeezing and correlation of the output signal and meter waves, and both improved operation as a quantum optical tap and as a quantum state preparator. The all-solid-state system was operated for 5 h with high stability.
A novel scheme for continuous-wave quantum nondemolition (QND) detection of optical-amplitude quadratures is implemented using a degenerate optical parametric amplifier. A monolithic ring resonator with optimizable frustrated total internal reflection coupling is used. Signal and meter output beams are squeezed by 0.5 dB and 2.2 dB, and 38% correlated. This implies the first realization of individually squeezed twin beams, as well as quantum state preparation ability for both output beams. A quantum optical tap efficiency T s + T m = 1.08 is achieved. The all-solid-state system was completely stabilized and continuously operated as a QND device for up to 36 hours.
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.