56 research outputs found
Seeing spin dynamics in atomic gases
The dynamics of internal spin, electronic orbital, and nuclear motion states
of atoms and molecules have preoccupied the atomic and molecular physics
community for decades. Increasingly, such dynamics are being examined within
many-body systems composed of atomic and molecular gases. Our findings
sometimes bear close relation to phenomena observed in condensed-matter
systems, while on other occasions they represent truly new areas of
investigation. I discuss several examples of spin dynamics that occur within
spinor Bose-Einstein gases, highlighting the advantages of spin-sensitive
imaging for understanding and utilizing such dynamics.Comment: Chapter in upcoming Review Volume entitled "From Atomic to Mesoscale:
The Role of Quantum Coherence in Systems of Various Complexities" from World
Scientifi
Cavity-assisted measurement and coherent control of collective atomic spin oscillators
We demonstrate continuous measurement and coherent control of the collective
spin of an atomic ensemble undergoing Larmor precession in a high-finesse
optical cavity. The coupling of the precessing spin to the cavity field yields
phenomena similar to those observed in cavity optomechanics, including cavity
amplification, damping, and optical spring shifts. These effects arise from
autonomous optical feedback onto the atomic spin dynamics, conditioned by the
cavity spectrum. We use this feedback to stabilize the spin in either its high-
or low-energy state, where, in equilibrium with measurement back-action
heating, it achieves a steady-state temperature, indicated by an asymmetry
between the Stokes and anti-Stokes scattering rates. For sufficiently large
Larmor frequency, such feedback stabilizes the spin ensemble in a nearly pure
quantum state, in spite of continuous measurement by the cavity field.Comment: 5 pages, 4 figures, and supplemental materia
Laser Cooling of Transition Metal Atoms
We propose the application of laser cooling to a number of transition-metal
atoms, allowing numerous bosonic and fermionic atomic gases to be cooled to
ultra-low temperatures. The non-zero electron orbital angular momentum of these
atoms implies that strongly atom-state-dependent light-atom interactions occur
even for light that is far-detuned from atomic transitions. At the same time,
many transition-metal atoms have small magnetic dipole moments in their
low-energy states, reducing the rate of dipolar-relaxation collisions.
Altogether, these features provide compelling opportunities for future
ultracold-atom research. Focusing on the case of atomic titanium, we identify
the metastable state as supporting a optical
transition with properties similar to the D2 transition of alkali atoms, and
suited for laser cooling. The high total angular momentum and electron spin of
this state suppresses leakage out of the the nearly closed optical transition
to a branching ratio estimated below . Following the pattern
exemplified by titanium, we identify optical transitions that are suited for
laser cooling of elements in the scandium group (Sc, Y, La), the titanium group
(Ti, Zr), the vanadium group (V, Nb), the manganese group (Mn, Tc), and the
iron group (Fe, Ru).Comment: 12 pages, 6 figure
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