Laser cooling of ions in a neutral plasma

Science ◽  
2019 ◽  
Vol 363 (6422) ◽  
pp. 61-64 ◽  
Author(s):  
Thomas K. Langin ◽  
Grant M. Gorman ◽  
Thomas C. Killian
Keyword(s):  
Laser Cooling ◽  
Optical Forces ◽  
Plasma Expansion ◽  
Laboratory Studies ◽  
Ion Temperature ◽  
Plasma Confinement ◽  
Strongly Coupled ◽  
Plasma State ◽  
Neutral Plasma ◽  
Current Kinetic

Laser cooling of a neutral plasma is a challenging task because of the high temperatures typically associated with the plasma state. By using an ultracold neutral plasma created by photoionization of an ultracold atomic gas, we avoid this obstacle and demonstrate laser cooling of ions in a neutral plasma. After 135 microseconds of cooling, we observed a reduction in ion temperature by up to a factor of four, with the temperature reaching as low as 50(4) millikelvin. This pushes laboratory studies of neutral plasmas deeper into the strongly coupled regime, beyond the limits of validity of current kinetic theories for calculating transport properties. The same optical forces also retard the plasma expansion, opening avenues for neutral-plasma confinement and manipulation.

scholarly journals Ion temperature evolution in an ultracold neutral plasma

2015 ◽  
Vol 22 (3) ◽  
pp. 033513 ◽  
Author(s):  
P. McQuillen ◽  
T. Strickler ◽  
T. Langin ◽  
T. C. Killian
Keyword(s):  
Temperature Evolution ◽  
Ion Temperature ◽  
Neutral Plasma

scholarly journals Ag nanocluster synthesis by laser ablation in Ar atmosphere: A plume dynamics analysis

2009 ◽  
Vol 27 (2) ◽  
pp. 281-290 ◽  
Author(s):  
E. Fazio ◽  
F. Neri ◽  
P.M. Ossi ◽  
N. Santo ◽  
S. Trusso
Keyword(s):  
Laser Ablation ◽  
Film Growth ◽  
Deposition Process ◽  
Morphological Properties ◽  
Plasma Expansion ◽  
Plasma Confinement ◽  
Time Resolved ◽  
Transmission Electron ◽  
Ambient Gas ◽  
Photography Analysis

AbstractAg thin films were deposited by pulsed laser ablation in a controlled Ar atmosphere. The deposition process was performed at different Ar pressure values in the range between 10 and 100 Pa to investigate the influence of ambient gas pressure on the plasma expansion dynamics and on the film structural properties. Position, velocity and volume of the laser generated plasma as functions of time were obtained by time resolved fast photography. The morphological properties of the films were investigated by transmission electron microscopy which shows that film growth proceeds via aggregation on the substrates of nanoclusters formedin the expandingplume. The formation of nanoparticles takes place as a consequence of plasma confinement induced by the interaction with ambient gas species. Data from fast photography analysis were used as input parameters to calculate the size of the nanoparticles using a model that takes into account the collisional nature of the laser generated silver plasma.

scholarly journals Optomechanical measurement of photon spin angular momentum and optical torque in integrated photonic devices

2016 ◽  
Vol 2 (9) ◽  
pp. e1600485 ◽  
Author(s):  
Li He ◽  
Huan Li ◽  
Mo Li
Keyword(s):  
Angular Momentum ◽  
Optical Tweezers ◽  
Laser Cooling ◽  
Photonic Devices ◽  
Mechanical Effect ◽  
Linear Momentum ◽  
Polarization Degree ◽  
Optical Forces ◽  
Spin Angular Momentum ◽  
Optical Torque

Photons carry linear momentum and spin angular momentum when circularly or elliptically polarized. During light-matter interaction, transfer of linear momentum leads to optical forces, whereas transfer of angular momentum induces optical torque. Optical forces including radiation pressure and gradient forces have long been used in optical tweezers and laser cooling. In nanophotonic devices, optical forces can be significantly enhanced, leading to unprecedented optomechanical effects in both classical and quantum regimes. In contrast, to date, the angular momentum of light and the optical torque effect have only been used in optical tweezers but remain unexplored in integrated photonics. We demonstrate the measurement of the spin angular momentum of photons propagating in a birefringent waveguide and the use of optical torque to actuate rotational motion of an optomechanical device. We show that the sign and magnitude of the optical torque are determined by the photon polarization states that are synthesized on the chip. Our study reveals the mechanical effect of photon’s polarization degree of freedom and demonstrates its control in integrated photonic devices. Exploiting optical torque and optomechanical interaction with photon angular momentum can lead to torsional cavity optomechanics and optomechanical photon spin-orbit coupling, as well as applications such as optomechanical gyroscopes and torsional magnetometry.

Atmospheric electron–ion and ion–ion recombination processes

1969 ◽  
Vol 47 (10) ◽  
pp. 1711-1719 ◽  
Author(s):  
Manfred A. Biondi
Keyword(s):  
Dissociative Recombination ◽  
Laboratory Studies ◽  
Ion Temperature ◽  
Air Ions ◽  
Atomic Ions ◽  
Recombination Processes ◽  
D Region ◽  
Ion Recombination ◽  
Three Body ◽  
Large Coefficient

The electron–ion and ion–ion recombination processes of importance in the upper atmosphere are considered, and available laboratory experimental and theoretical information concerning the relevant processes is discussed. For atomic ions the principal electron–ion recombination process is radiative, with theory indicating that the two-body coefficient at ∼200 °K is ∼10−11 cm3/s and decreases with increasing electron temperature. Microwave afterglow/mass spectrometer studies of diatomic ionospheric ions (e.g. NO+, O2+, and N2+) show a loss by dissociative recombination with a coefficient substantially in excess of 10−7 cm3/s at 250 °K and decreasing with increasing electron and ion temperature. There is some evidence from flame studies that H3O+ ions exhibit a very large coefficient (10−6–10−5 cm3/s) at 300 °K. Ion–ion recombination evidently proceeds by mutual neutralization, with laboratory studies of ions such as NO+ and NO2− indicating a two-body coefficient of the order of 10−7 cm3/s at 300 °K. In the lower D region, three-body Thomson recombination may be important, since laboratory studies of "air" ions indicate a three-body coefficient of ∼2 × 10−25 cm6/s at 300 °K.

scholarly journals Ultracold neutral plasma expansion in two dimensions

2005 ◽  
Vol 12 (12) ◽  
pp. 123501 ◽  
Author(s):  
E. A. Cummings ◽  
J. E. Daily ◽  
D. S. Durfee ◽  
S. D. Bergeson
Keyword(s):  
Two Dimensions ◽  
Plasma Expansion ◽  
Neutral Plasma

Optical forces and laser cooling

2016 ◽  
pp. 347-366
Author(s):  
Peter van der Straten ◽  
Harold Metcalf
Keyword(s):  
Laser Cooling ◽  
Optical Forces
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