Magnetometry via a double-pass continuous quantum measurement of atomic spin

Bradley A. Chase, Ben Q. Baragiola, Heather L. Partner, Brigette D. Black, J. M. Geremia

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)


We argue that it is possible in principle to reduce the uncertainty of an atomic magnetometer by double passing a far-detuned laser field through the atomic sample as it undergoes Larmor precession. Numerical simulations of the quantum Fisher information suggest that, despite the lack of explicit multibody coupling terms in the system's magnetic Hamiltonian, the parameter estimation uncertainty in such a physical setup scales better than the conventional Heisenberg uncertainty limit over a specified but arbitrary range of particle number. Using the methods of quantum stochastic calculus and filtering theory, we demonstrate numerically an explicit parameter estimator (called a quantum particle filter) whose observed scaling follows that of our calculated quantum Fisher information. Moreover, the quantum particle filter quantitatively surpasses the uncertainty limit calculated from the quantum Cramér-Rao inequality based on a magnetic coupling Hamiltonian with only single-body operators. We also show that a quantum Kalman filter is insufficient to obtain super-Heisenberg scaling and present evidence that such scaling necessitates going beyond the manifold of Gaussian atomic states.

Original languageEnglish
Article number062107
Pages (from-to)1-17
Number of pages17
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Issue number6
Publication statusPublished - 15 Jun 2009
Externally publishedYes


Dive into the research topics of 'Magnetometry via a double-pass continuous quantum measurement of atomic spin'. Together they form a unique fingerprint.

Cite this