arXiv subjects

Stefan Danilishin

Publications and source records attributed to Stefan Danilishin.

12 recordsLinked to original sources

arXiv2025

Frequency-dependent squeezing for gravitational-wave detection through quantum teleportation

Ground-based interferometric gravitational wave detectors are highly precise sensors for weak forces, limited in sensitivity across their detection band by quantum fluctuations of light. Current and future instruments address this limitation by injecting frequency-dependent squeezed vacuum into the detection port, utilizing narrow-band, low-loss optical cavities for optimal rotation of the squeezing ellipse at each signal frequency. This study introduces a novel scheme employing the principles of quantum teleportation and entangled states of light. It allows achieving broadband suppression of quantum noise in detuned signal recycled-Fabry-Perot--Michelson interferometers, which is the baseline design of the low-frequency detector within the Einstein Telescope xylophone detector, without requiring additional filter cavities or modifications to the core optics of the main interferometer.

quant-ph↗

arXiv2021

3G R&D: R&D for the Next Generation of Ground-based Gravitational-wave Detectors

To deliver on the promise of next generation gravitational-wave observatories, a sustained and coordinated detector research and development program is required. This report examines in detail the wide range of nearer- and longer-term detector R&D programs needed for next generation GW detectors commensurate with the key science targets presented in "The Next Generation Global Gravitational Wave Observatory: The Science Book", including considerations of site selection and large-scale vacuum infrastructure. The report makes a series of detailed recommendations on the needed advances in detector technology and the timescales needed to achieve those advances. It also identifies areas where larger-scale globally coordinated R&D efforts will be critical to ensuring success while minimizing costs. This report is the third in a six part series of reports by the GWIC 3G Subcommittee: i) Expanding the Reach of Gravitational Wave Observatories to the Edge of the Universe, ii) The Next Generation Global Gravitational Wave Observatory: The Science Book, iii) 3G R&D: R&D for the Next Generation of Ground-based Gravitational Wave Detectors (this report), iv) Gravitational Wave Data Analysis: Computing Challenges in the 3G Era, v) Future Ground-based Gravitational-wave Observatories: Synergies with Other Scientific Communities, and vi) An Exploration of Possible Governance Models for the Future Global Gravitational-Wave Observatory Network.

gr-qc↗

arXiv2021

Enhancing high frequency sensitivity of gravitational wave detectors with sloshing-Sagnac interferometer

Sensitivity of gravitational-wave detectors is limited in the high-frequency band by quantum shot noise and eventually limited by the optical loss in signal recycling cavity. This limit is the main obstacle on the way to detect gravitational waves from the binary neutron star mergers in the current and the future generation detectors, as it does not depend on either the arm length, or the injected squeezing level. In this paper, we come up with the sloshing Sagnac interferometer topology, which can be obtained from the Michelson interferometer by optically connecting the end mirrors into an additional optical cavity. This transforms the interferometer into a triply-coupled cavity system capable of beating the loss-induced high-frequency limit of the signal-recycled Michelson interferometer. With advanced LIGO+ comparable parameters, a sloshing-Sagnac scheme can achieve 7 times better sensitivity at 2.5\,kHz or 4 times better signal to noise ratio for a typical waveform of binary neutron post merge. Being an evolution of Michelson interferometer, the sloshing-Sagnac interferometer can possibly be used as a topology for the future generation detectors and upgrade of current detectors.

gr-qc↗

arXiv2013

Observation of Three-Mode Parametric Instability

Three-mode parametric interactions can occur in triply-resonant opto-mechanical systems in which two orthogonal optical modes are coupled with an appropriate mechanical mode. Using an optical cavity with a membrane inside, we report the first observation of three-mode parametric instability in a Fabry-Perot cavity, a phenomenon predicted to occur in long baseline advanced gravitational wave detectors. We present a large signal model for the phenomenon, which predicts exponential growth of mechanical oscillation followed by saturation. Our experimental results are consistent with this model. Contrary to expectations, parametric instability does not lead to loss of cavity lock, a fact which may make it easier to implement control techniques in Advanced gravitational wave detectors.

physics.optics↗

arXiv2012

Quantum-state steering in optomechanical devices

We show that optomechanical systems in the quantum regime can be used to demonstrate EPR-type quantum entanglement between the optical field and the mechanical oscillator, via quantum-state steering. Namely, the conditional quantum state of the mechanical oscillator can be steered into different quantum states depending the choice made on which quadrature of the out-going field is to be measured via homodyne detection. More specifically, if quantum radiation pressure force dominates over thermal force, the oscillator's quantum state is steerable with a photodetection efficiency as low as 50%, approaching the ideal limit shown by Wiseman and Gambetta [Phys. Rev. Lett. {\bf 108}, 220402 (2012)]. We also show that requirement for steerability is the same as those for achieving sub-Heisenberg state tomography using the same experimental setup.

quant-ph↗

arXiv2010

Negative optical inertia for enhancing the sensitivity of future gravitational-wave detectors

We consider enhancing the sensitivity of future gravitational-wave detectors by using double optical spring. When the power, detuning and bandwidth of the two carriers are chosen appropriately, the effect of the double optical spring can be described as a "negative inertia", which cancels the positive inertia of the test masses and thus increases their response to gravitational waves. This allows us to surpass the free-mass Standard Quantum Limit (SQL) over a broad frequency band, through signal amplification, rather than noise cancelation, which has been the case for all broadband SQL-beating schemes so far considered for gravitational-wave detectors. The merit of such signal amplification schemes lies in the fact that they are less susceptible to optical losses than noise cancelation schemes. We show that it is feasible to demonstrate such an effect with the {\it Gingin High Optical Power Test Facility}, and it can eventually be implemented in future advanced GW detectors.

gr-qc↗

arXiv2010

Achieving ground state and enhancing entanglement by recovering information

For cavity-assisted optomechanical cooling experiments, it has been shown in the literature that the cavity bandwidth needs to be smaller than the mechanical frequency in order to achieve the quantum ground state of the mechanical oscillator, which is the so-called resolved-sideband or good-cavity limit. We provide a new but physically equivalent insight into the origin of such a limit: that is information loss due to a finite cavity bandwidth. With an optimal feedback control to recover those information, we can surpass the resolved-sideband limit and achieve the quantum ground state. Interestingly, recovering those information can also significantly enhance the optomechanical entanglement. Especially when the environmental temperature is high, the entanglement will either exist or vanish critically depending on whether information is recovered or not, which is a vivid example of a quantum eraser.

quant-ph↗

arXiv2010

Probing macroscopic quantum states with a sub-Heisenberg accuracy

Significant achievements in the reduction of classical-noise floor will allow macroscopic systems to prepare nearly Heisenberg-Limited quantum states through a continuous measurement, i.e. conditioning. In order to probe the conditional quantum state and confirm quantum dynamics, we propose use of an optimal time-domain variational measurement, in which the homodyne detection phase varies in time. This protocol allows us to characterize the macroscopic quantum state below the Heisenberg Uncertainty -- i.e. Quantum Tomography -- and the only limitation comes from readout loss which enters in a similar manner as the frequency-domain variational scheme proposed by Kimble et al.. In the case of no readout loss, it is identical to the back-action-evading scheme invented by Vyatchanin et al. for detecting gravitational-wave (GW) signal with known arrival time. As a special example and to motivate Macroscopic Quantum Mechanics (MQM) experiments with future GW detectors, we mostly focus on the free-mass limit -- the characteristic measurement frequency is much higher than the oscillator frequency -- and further assume the classical noises are Markovian, which captures the main feature of a broadband GW detector. Besides, we consider verifications of Einstein-Podolsky-Rosen (EPR) type entanglements between macroscopic test masses in GW detectors, which enables to test one particular version of Gravity Decoherence conjectured by Diosi and Penrose.

quant-ph↗

arXiv2010

Preparing a mechanical oscillator in non-Gaussian quantum states

We propose a protocol for coherently transferring non-Gaussian quantum states from optical field to a mechanical oscillator. The open quantum dynamics and continuous-measurement process, which can not be treated by the stochastic-master-equation formalism, are studied by a new path-integral-based approach. We obtain an elegant relation between the quantum state of the mechanical oscillator and that of the optical field, which is valid for general linear quantum dynamics. We demonstrate the experimental feasibility of such protocol by considering the cases of both large-scale gravitational-wave detectors and small-scale cavity-assisted optomechanical devices.

quant-ph↗

arXiv2009

Universal Quantum Entanglement between an Oscillator and Continuous Fields

Quantum entanglement has been actively sought for in optomechanical and electromechanical systems. The simplest such system is a mechanical oscillator interacting with a coherent beam, while the oscillator also suffers from thermal decoherence. For this system, we show that quantum entanglement is always present between the oscillator and continuous outgoing fields -- even when the environmental temperature is high and the oscillator is highly classical. Such universal entanglement is also shown to be able to survive more than one oscillation cycle if characteristic frequency of the optomechanical interaction is larger than that of the thermal noise. Furthermore, we derive the effective optical mode that is maximally entangled with the oscillator, which will be useful for future quantum computing and encoding information into mechanical degrees of freedom.

quant-ph↗

arXiv2009

Standard Quantum Limit for Probing Mechanical Energy Quantization

We derive a standard quantum limit for probing mechanical energy quantization in a class of systems with mechanical modes parametrically coupled to external degrees of freedom. To resolve a single mechanical quantum, it requires a strong-coupling regime -- the decay rate of external degrees of freedom is smaller than the parametric coupling rate. In the case for cavity-assisted optomechanical systems, e.g. the one proposed by Thompson et al., zero-point motion of the mechanical oscillator needs to be comparable to linear dynamical range of the optical system which is characterized by the optical wavelength divided by the cavity finesse.

quant-ph↗

arXiv2008

Creation of a quantum oscillator by classical control

As a pure quantum state is being approached via linear feedback, and the occupation number approaches and eventually goes below unity, optimal control becomes crucial. We obtain theoretically the optimal feedback controller that minimizes the uncertainty for a general linear measurement process, and show that even in the absence of classical noise, a pure quantum state is not always achievable via feedback. For Markovian measurements, the deviation from minimum Heisenberg Uncertainty is found to be closely related to the extent to which the device beats the free-mass Standard Quantum Limit for force measurement. We then specialize to optical Markovian measurements, and demonstrate that a slight modification to the usual input-output scheme -- either injecting frequency independent squeezed vacuum or making a homodyne detection at a non-phase quadrature -- allows controlled states of kilogram-scale mirrors in future LIGO interferometers to reach occupation numbers significantly below unity.

quant-ph↗