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Quantum Electronics and Laser Science Conference

Continuous-wave back-action evasion measurement with a dual port parametric amplifier

Robert Bruckmeier, К. R. Schneider, Hauke Hansen, Stephan Schiller, J. Mlynek

Published Jun 2, 1996• 0 citations
OpenAlex

Abstract

Summary form only given. Quantum nondemolition (QND) measurements seek to measure a quantum mechanical observable precisely without disturbing the observable itself and its time evolution. They are of great importance in precision metrology and information processing at the quantum level. In this work, a new QND scheme for optical continuous-wave measurements of quadrature observables using a degenerate, type-I phasematched, dual port, optical parametric amplifier (OPA), is implemented. We employ a low-loss monolithic MgO:LiNbO/sub 3/ ring resonator.

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Back-Action Evasion Using Parametric Downconversion

Arthur La Porta, R. E. Slusher, B. Yurke

The uncertainty principle in general requires that "back-action" noise is introduced into an optical field after it has been measured, so that the precision of subsequent measurements is progressively reduced. However, it has been shown that one quadrature component of the field can be measured without changing its quantum state; i.e. a quantum nondemolition, or more precisely, a back-action evasion measurement can be performed.

Annual Meeting Optical Society of America•Jan 1, 1988•0 citations

Using feedback to eliminate back-action in quantum measurements

Howard M. Wiseman

A quantum-nondemolition (QND) measurement is one which does not disturb the quantity it measures. Any measurement can be regarded as a QND measurement followed by an additional back-action which may disturb that quantity. By feeding back the measurement result to control the system dynamics, this back-action can always be eliminated in principle. A practical device based on homodyne measurement of the x quadrature of a cavity mode is investigated. First, a ${\mathrm{\ensuremath{\chi}}}^{(2)}$ crystal is inserted in the cavity so that it becomes a degenerate parametric oscillator at threshold. Then the photocurrent is used to control coherent driving of the cavity, so as to give positive feedback with unit gain. This feedback, combined with the nonlinearity, turns the homodyne measurement into a QND measurement of x. The device can also be used to measure the x quadrature of a traveling wave, and gives near-perfect QND correlations over a large bandwidth. However, the quality of the measurement is badly degraded by even slightly inefficient photodetectors.

Physical Review A•Mar 1, 1995•72 citations
Summary form only given. Quantum nondemolition (QND) measurements seek to measure a quantum mechanical observable precisely without disturbing the observable itself and its time evolution. They are of great importance in precision metrology and information processing at the quantum level. In this work, a new QND scheme for optical continuous-wave measurements of quadrature observables using a degenerate, type-I phasematched, dual port, optical parametric amplifier (OPA), is implemented. We employ a low-loss monolithic MgO:LiNbO/sub 3/ ring resonator.
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.
Realization of a room-temperature ultrafast photon-number-resolving quantum nondemolition (QND) measurement would have significant implications for photonic quantum information processing, enabling, for example, deterministic quantum computation in discrete-variable architectures, but the requirement for strong coupling has hampered the development of scalable implementations.In this work, we propose and analyze a nonlinear-optical route to photon-number-resolving QND using quadratic (i.e., χ (2) ) nonlinear interactions.We show that the coherent pump field driving a frequency-detuned optical parametric amplifier (OPA) experiences displacements conditioned on the number of signal Bogoliubov excitations.A measurement of the pump displacement thus provides a QND measurement of the signal Bogoliubov excitations, projecting the signal mode to a squeezed photon-number state.We then show how our nonlinear OPA dynamics can be utilized to deterministically generate Gottesman-Kitaev-Preskill states with only additional Gaussian resources, offering an all-optical route for fault-tolerant quantum information processing in continuous-variable systems.Finally, we place these QND schemes into a more traditional context by highlighting analogies between the frequency-detuned optical parametric oscillator and multilevel atom-cavity quantum electrodynamics systems by showing how continuous monitoring of the outcoupled pump quadrature induces conditional localization of the intracavity signal mode onto squeezed photon-number states.Our analysis suggests that our proposal may be viable in near-term χ (2) nonlinear nanophotonics, highlighting the rich potential of the OPA as a universal tool for ultrafast non-Gaussian quantum state engineering and quantum computation.
A quantum-nondemolition (QND) measurement is one which does not disturb the quantity it measures. Any measurement can be regarded as a QND measurement followed by an additional back-action which may disturb that quantity. By feeding back the measurement result to control the system dynamics, this back-action can always be eliminated in principle. A practical device based on homodyne measurement of the x quadrature of a cavity mode is investigated. First, a ${\mathrm{\ensuremath{\chi}}}^{(2)}$ crystal is inserted in the cavity so that it becomes a degenerate parametric oscillator at threshold. Then the photocurrent is used to control coherent driving of the cavity, so as to give positive feedback with unit gain. This feedback, combined with the nonlinearity, turns the homodyne measurement into a QND measurement of x. The device can also be used to measure the x quadrature of a traveling wave, and gives near-perfect QND correlations over a large bandwidth. However, the quality of the measurement is badly degraded by even slightly inefficient photodetectors.