51 research outputs found
Paired carriers as a way to reduce quantum noise of multi-carrier gravitational-wave detectors
We explore new regimes of laser interferometric gravitational-wave detectors
with multiple optical carriers which allow to reduce the quantum noise of these
detectors. In particular, we show that using two carriers with the opposite
detunings, homodyne angles, and squeezing angles, but identical other
parameters (the antisymmetric carriers), one can suppress the quantum noise in
such a way that its spectrum follows the Standard Quantum Limit (SQL) at low
frequencies. Relaxing this antisymmetry condition, it is also possible to
slightly overcome the SQL in broadband. Combining several such pairs in the
xylophone configuration, it is possible to shape the quantum noise spectrum
flexibly
Improving Kerr QND measurement sensitivity via squeezed light
In ref [Phys. Rev. A 106, 013720], the scheme of quantum non-demolition
measurement of optical quanta that uses a resonantly enhanced Kerr nonlinearity
in optical microresonators was analyzed theoretically. It was shown that using
the modern high-Q microresonators, it is possible to achieve the sensitivity
several times better than the standard quantum limit. Here we propose and
analyze in detail a significantly improved version of that scheme. We show,
that by using a squeezed quantum state of the probe beam and the anti-squeezing
(parametric amplification) of this beam at the output of the microresonator, it
is possible to reduce the measurement imprecision by about one order of
magnitude. The resulting sensitivity allows to generate and verify multi-photon
non-Gaussian quantum states of light, making the scheme considered here
interesting for the quantum information processing tasks.Comment: Updated and improved version, 8 pages, 4 figure
Anomalous dynamic back-action in interferometers
We analyze the dynamic optomechanical back-action in signal-recycled
Michelson and Michelson-Sagnac interferometers that are operated off dark port.
We show that in this case --- and in contrast to the well-studied canonical
form of dynamic back-action on dark port --- optical damping in a
Michelson-Sagnac interferometer acquires a non-zero value on cavity resonance,
and additional stability/instability regions on either side of the resonance,
revealing new regimes of cooling/heating of micromechanical oscillators. In a
free-mass Michelson interferometer for a certain region of parameters we
predict a stable single-carrier optical spring (positive spring and positive
damping), which can be utilized for the reduction of quantum noise in
future-generation gravitational-wave detectors.Comment: 9 pages, 5 figures. Paper reorganize
Energetic Quantum Limit in Large-Scale Interferometers
For each optical topology of an interferometric gravitational wave detector,
quantum mechanics dictates a minimum optical power (the ``energetic quantum
limit'') to achieve a given sensitivity. For standard topologies, when one
seeks to beat the standard quantum limit by a substantial factor, the energetic
quantum limit becomes impossibly large. Intracavity readout schemes may do so
with manageable optical powers.Comment: Revised version; to be published in Proceedings of the 1999 Edoardo
Amaldi Conference on Gravitational Waves; 11 pages including figures;
manuscript is RevTex; figures are .eps; an AIP style file is include
Gravitational wave detection beyond the standard quantum limit using a negative-mass spin system and virtual rigidity
Gravitational wave detectors (GWDs), which have brought about a new era in
astronomy, have reached such a level of maturity that further improvement
necessitates quantum-noise-evading techniques. Numerous proposals to this end
have been discussed in the literature, e.g., invoking frequency-dependent
squeezing or replacing the current Michelson interferometer topology by that of
the quantum speedmeter. Recently, a proposal based on the linking of a standard
interferometer to a negative-mass spin system via entangled light has offered
an unintrusive and small-scale new approach to quantum noise evasion in GWDs
[Phys. Rev. Lett. , 031101 (2018)]. The solution proposed therein
does not require modifications to the highly refined core optics of the present
GWD design and, when compared to previous proposals, is less prone to losses
and imperfections of the interferometer. In the present article, we refine this
scheme to an extent that the requirements on the auxiliary spin system are
feasible with state-of-the-art implementations. This is accomplished by
matching the effective (rather than intrinsic) susceptibilities of the
interferometer and spin system using the virtual rigidity concept, which, in
terms of implementation, requires only suitable choices of the various
homodyne, probe, and squeezing phases.Comment: Minor typos fixed, minor editing; 12 pages, 5 figure
Advanced quantum techniques for future gravitational-wave detectors
Quantum fluctuation of light limits the sensitivity of advanced laser interferometric gravitational-wave detectors. It is one of the principal obstacles on the way towards the next-generation gravitational-wave observatories. The envisioned significant improvement of the detector sensitivity requires using quantum non-demolition measurement and back-action evasion techniques, which allow us to circumvent the sensitivity limit imposed by the Heisenberg uncertainty principle. In our previous review article (Danilishin and Khalili in Living Rev Relativ 15:5, 2012), we laid down the basic principles of quantum measurement theory and provided the framework for analysing the quantum noise of interferometers. The scope of this paper is to review novel techniques for quantum noise suppression proposed in the recent years and put them in the same framework. Our delineation of interferometry schemes and topologies is intended as an aid in the process of selecting the design for the next-generation gravitational-wave observatories. © 2019, The Author(s)
Quantum back-action in measurements of zero-point mechanical oscillations
Measurement-induced back action, a direct consequence of the Heisenberg
Uncertainty Principle, is the defining feature of quantum measurements. We use
quantum measurement theory to analyze the recent experiment of Safavi-Naeini et
al. [Phys. Rev. Lett. {\bf 108}, 033602 (2012)], and show that results of this
experiment not only characterize the zero-point fluctuation of a
near-ground-state nanomechanical oscillator, but also demonstrate the existence
of quantum back-action noise --- through correlations that exist between
sensing noise and back-action noise. These correlations arise from the quantum
coherence between the mechanical oscillator and the measuring device, which
build up during the measurement process, and are key to improving sensitivities
beyond the Standard Quantum Limit.Comment: 11 pages and 4 figure
Observation of generalized optomechanical coupling and cooling on cavity resonance
Optomechanical coupling between a light field and the motion of a cavity
mirror via radiation pressure plays an important role for the exploration of
macroscopic quantum physics and for the detection of gravitational waves (GWs).
It has been used to cool mechanical oscillators into their quantum ground
states and has been considered to boost the sensitivity of GW detectors, e.g.
via the optical spring effect. Here, we present the experimental
characterization of generalized, that is, dispersive and dissipative
optomechanical coupling, with a macroscopic (1.5mm)^2-sized silicon nitride
(SiN) membrane in a cavity-enhanced Michelson-type interferometer. We report
for the first time strong optomechanical cooling based on dissipative coupling,
even on cavity resonance, in excellent agreement with theory. Our result will
allow for new experimental regimes in macroscopic quantum physics and GW
detection
Increasing the sensitivity of future gravitational-wave detectors with double squeezed-input
We consider improving the sensitivity of future interferometric
gravitational-wave detectors by simultaneously injecting two squeezed vacuums
(light), filtered through a resonant Fabry-Perot cavity, into the dark port of
the interferometer.The same scheme with single squeezed vacuum was first
proposed and analyzed by Corbitt et al. Here we show that the extra squeezed
vacuum, together with an additional homodyne detection suggested previously by
one of the authors, allows reduction of quantum noise over the entire detection
band. To motivate future implementations, we take into account a realistic
technical noise budget for Advanced LIGO (AdvLIGO) and numerically optimize the
parameters of both the filter and the interferometer for detecting
gravitational-wave signals from two important astrophysics sources, namely
Neutron-Star--Neutron-Star (NSNS) binaries and Bursts. Assuming the optical
loss of the 30m filter cavity to be 10ppm per bounce and 10dB squeezing
injection, the corresponding quantum noise with optimal parameters lowers by a
factor of 10 at high frequencies and goes below the technical noise at low and
intermediate frequencies.Comment: 16 pages, 4 figures, Accepted by Phys. Rev.
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