Freiburg 2019 – wissenschaftliches Programm

Sitzungen | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

FM: Fall Meeting

FM 24: Quantum Sensing: Entanglement and Beyond Shot Noise

FM 24.5: Talk

Montag, 23. September 2019, 17:30–17:45, 3044

Approximate quantum non-demolition measurementsSami Boulebnane, Mischa P. Woods, and •Joseph M. Renes — Institute of Theoretical Physics, ETH Zürich

With the advent of gravitational wave detectors employing squeezed light, quantum waveform estimation---estimating a time-dependent signal by means of a quantum-mechanical probe---is of increasing importance. As is well known, backaction of quantum measurement limits the precision with which the waveform can be estimated, though these limits can in principle be overcome by ``quantum nondemolition'' (QND) measurement setups found in the literature. Strictly speak- ing, however, their implementation would require infinite energy, as their mathematical description involves Hamiltonians unbounded from below. This raises the question of how well one may approx- imate nondemolition setups with finite energy or finite-dimensional realizations. Here we consider a finite-dimensional waveform estimation setup based on the ``quasi-ideal clock'' and show that the estimation errors due to approximating the QND condition decrease slowly, as a power law, with increasing dimension. As a result, we find that good QND approximations require large energy or dimensionality. We argue that this result can be expected to also hold for setups based on truncated oscillators or spin systems.

100% | Mobil-Ansicht | English Version | Kontakt/Impressum/Datenschutz
DPG-Physik > DPG-Verhandlungen > 2019 > Freiburg