36,134 research outputs found
Supermassive Black Hole Tests of General Relativity with eLISA
Motivated by the parameterized post-Einsteinian (ppE) scheme devised by Yunes
and Pretorius, which introduces corrections to the post-Newtonian coefficients
of the frequency domain gravitational waveform in order to emulate alternative
theories of gravity, we compute analytical time domain waveforms that, after a
numerical Fourier transform, aim to represent (phase corrected only) ppE
waveforms. In this formalism, alternative theories manifest themselves via
corrections to the phase and frequency, as predicted by General Relativity
(GR), at different post-Newtonian (PN) orders. In order to present a generic
test of alternative theories of gravity, we assume that the coupling constant
of each alternative theory is manifestly positive, allowing corrections to the
GR waveforms to be either positive or negative. By exploring the capabilities
of massive black hole binary GR waveforms in the detection and parameter
estimation of corrected time domain ppE signals, using the current eLISA
configuration (as presented for the ESA Cosmic Vision L3 mission), we
demonstrate that for corrections arising at higher than 1PN order in phase and
frequency, GR waveforms are sufficient for both detecting and estimating the
parameters of alternative theory signals. However, for theories introducing
corrections at the 0 and 0.5 PN order, GR waveforms are not capable of covering
the entire parameter space, requiring the use of non-GR waveforms for detection
and parameter estimation.Comment: 13 pages, 5 figure
Optomechanical state reconstruction and nonclassicality verification beyond the resolved-sideband regime
Quantum optomechanics uses optical means to generate and manipulate quantum
states of motion of mechanical resonators. This provides an intriguing platform
for the study of fundamental physics and the development of novel quantum
devices. Yet, the challenge of reconstructing and verifying the quantum state
of mechanical systems has remained a major roadblock in the field. Here, we
present a novel approach that allows for tomographic reconstruction of the
quantum state of a mechanical system without the need for extremely high
quality optical cavities. We show that, without relying on the usual state
transfer presumption between light an mechanics, the full optomechanical
Hamiltonian can be exploited to imprint mechanical tomograms on a strong
optical coherent pulse, which can then be read out using well-established
techniques. Furthermore, with only a small number of measurements, our method
can be used to witness nonclassical features of mechanical systems without
requiring full tomography. By relaxing the experimental requirements, our
technique thus opens a feasible route towards verifying the quantum state of
mechanical resonators and their nonclassical behaviour in a wide range of
optomechanical systems.Comment: 12 pages + 9 pages of appendices, 4 figure
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