Spin noise at an arbitrary spin temperature
| dc.creator | Lee, S. -K. | |
| dc.date | 2008-04-22 | |
| dc.date.accessioned | 2026-07-07T09:34:02Z | |
| dc.date.available | 2026-07-07T09:34:02Z | |
| dc.description | An ensemble of spins oriented along the $z$ direction exhibits nonzero fluctuation in the transverse ($x$- and $y$-) components of the spin angular momentum in accordance with the uncertainty principle. When the spins obey a spin temperature distribution, the mean square fluctuation in $S_{x}$ can be calculated by ensemble average of the expectation value of $S_{x}^{2}$ with respect to an equilibrium density matrix $ρ=e^{βS_{z}}/Z$. The fluctuation can also be calculated from the fluctuation-dissipation theorem as has been done in literature in the context of NMR spin noise. For spin 1/2 particles in the high temperature limit, appropriate for many NMR experiments, the two methods are known to produce the same, temperature-independent spin noise. We show that inclusion of the zero-point fluctuation term in the original Nyquist relation extends this correspondence to an arbitrary spin temperature for any spin $S$. This indicates that the uncertainty principle-limited spin projection noise can be viewed as a result of the zero-point fluctuation in the thermal bath coupled to the spins. | |
| dc.description | 3 pages, 1 figure | |
| dc.identifier | https://arxiv.org/abs/0804.3585 | |
| dc.identifier | http://arxiv.org/abs/0804.3585 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/159349 | |
| dc.subject | Atomic Physics | |
| dc.title | Spin noise at an arbitrary spin temperature | |
| dc.type | text |