%0 Generic %1 shankar2018continuous %A Shankar, Athreya %A Greve, Graham P. %A Wu, Baochen %A Thompson, James K. %A Holland, Murray %D 2018 %K non-demolition-measurement quantum_metrology theory %T Continuous real-time tracking of a quantum phase below the standard quantum limit %U http://arxiv.org/abs/1809.08216 %X We propose a scheme for continuously measuring an evolving quantum phase with precision beyond the standard quantum limit of $\Delta \phi_SQL = 1/N$ radians, where $N$ is the number of pseudospins. Quantum non-demolition measurements of a lossy cavity mode interacting with an atomic ensemble are used to directly probe the phase of the collective atomic spin without converting it into a population difference. Unlike traditional Ramsey measurement sequences, our scheme allows for real-time tracking of time-varying signals. As a bonus, spin-squeezed states develop naturally, providing real-time phase estimation significantly more precise than $\Delta \phi_SQL$.

@misc{shankar2018continuous, abstract = {We propose a scheme for continuously measuring an evolving quantum phase with precision beyond the standard quantum limit of $\Delta \phi_\text{SQL} = 1/\sqrt{N}$ radians, where $N$ is the number of pseudospins. Quantum non-demolition measurements of a lossy cavity mode interacting with an atomic ensemble are used to directly probe the phase of the collective atomic spin without converting it into a population difference. Unlike traditional Ramsey measurement sequences, our scheme allows for real-time tracking of time-varying signals. As a bonus, spin-squeezed states develop naturally, providing real-time phase estimation significantly more precise than $\Delta \phi_\text{SQL}$.}, added-at = {2018-10-01T14:47:38.000+0200}, author = {Shankar, Athreya and Greve, Graham P. and Wu, Baochen and Thompson, James K. and Holland, Murray}, biburl = {https://www.bibsonomy.org/bibtex/24ee789aff42db1a4903d862fc3e16676/marschu}, interhash = {b46e5e1b69be7de85ff7bf52da52a513}, intrahash = {4ee789aff42db1a4903d862fc3e16676}, keywords = {non-demolition-measurement quantum_metrology theory}, note = {cite arxiv:1809.08216Comment: 6 + 3 pages, 3 figures, includes Supplemental Material}, timestamp = {2018-11-13T09:56:35.000+0100}, title = {Continuous real-time tracking of a quantum phase below the standard quantum limit}, url = {http://arxiv.org/abs/1809.08216}, year = 2018 }