This can be preparation noise (e.g., due to imperfections in the optical switches/modulators or coming from the natural thermal background at lower frequencies19–23) as well as measurement noise and inefficiencies affecting the detectors (which could be genuine or even added by the honest ...
Weak limit (g→ 0): The system fails to couple to the detectors. The bound (26) reduces to minw2{−log(pj1Vpj2VTr(Πw2W))}. The probability distribution {pjℓV} has a spread quantified by the Shannon entropy HSh({pjℓV}). The left-hand side of Eq. (24) reduces to 2[...
The detectors, on the other hand, belong to real space where information gathered from them includes supplementary elements corresponding to energy that is exchanged in quanta. The granularity associated with this process does not belong to Hilbert space. Or, in other words, quantum mechanics does ...
These detectors can be considered the first quantum optomechanical devices. On the one hand, they still have not reached the SQL, which for a particular case of (almost) free 10-kg test masses used in the LIGO and around the best sensitivity frequency Ω ∼ 103 s−1 equals ΔxSQL∼...
But detecting gravitational waves isn’t easy. By the time they reach Earth, the ripples have dissipated into near silence. Our detectors must sense motions on the scale of one ten-thousandth the width of a proton to stand a chance. And making them more sensitive is a huge challenge. Physi...
A key element ofquantum mechanicsisHeisenberg’suncertainty principle, which forbids the simultaneous measurement of the position and momentum of a particle along the same direction, as so aptly illustrated by Tim Rickard above. for a photon, where E is the energy, c is the speed of light and...
and argues that, in any case, photon detectors are far more vulnerable to attack than the sources are, because they must receive whatever a potential eavesdropper can throw at them. “Our scheme is less beautiful than the theoretically perfect one,” he says, “but it is more practical.” ...
Thanks to Moore’s Law, it becomes possible to create complex digital signal processing on chip side-by-side with, or under the detectors, thus minimizing noise and jitter. Proximity of detection and processing maximizes compactness, while reducing power dissipation due to the lack of expensive an...
(MZIs). The signal photon was chosen at the wavelength of 1545.32 nm and the idler photon at 1554.94 nm. Single-photons were routed off-chip for detection by an array of fiber-coupled superconducting nanowire single-photon detectors (SNSPDs) with an averaged efficiency of 85%, and ...
32. We assumed that the largest reduced deflection in Fig. 3 of Ref.32 corresponds to the largest allowed value for Θ. A derived diameter of 0.347 cm is not unreasonable for beam detectors.) We then simulate the experiment signal of Ref.32 by constructing the apparent cross section σapp...