Category: Lasers

How Not to Control the Weather for Your Dog

Emmy, the Queen of Niskayuna, sitting in the snow hoping the camera will spit out some treats.

I’m rooting around in my bag for a pen, and pull out a laser pointer by mistake. Since I’d really prefer not to be grading, I flip it on and shine it on the floor next to the spot where Emmy is half-dozing. She immediately leaps up (she’s pretty spry for a dog of 12…),… Continue reading How Not to Control the Weather for Your Dog

Nobel Prize for Blue LEDs

Alfred Nobel's signature in blue LED's. From the Nobel Prize Twitter feed.

The 2014 Nobel Prize in Physics has been awarded to Isamu Akasaki, Hiroshi Amano and Shuji Nakamura for the development of blue LED’s. As always, this is kind of fascinating to watch evolve in the social media sphere, because as a genuinely unexpected big science story, journalists don’t have pre-written articles based on an early… Continue reading Nobel Prize for Blue LEDs

Yes Virginia, There Are Quantum Jumps

Quantum jumps, from the Wineland group paper described in the text. The top is a mercury ion with just the 194nm laser, the middle a single ion with both 194nm and 281nm lasers, and the bottom two ions in the same trap with both lasers.

In a weird coincidence, shortly after I wrote a post about “quantum leap” as a metaphor, I was looking up some stuff about John Bell and ran into mentions of a paper he wrote called “Are There Quantum Jumps?” Bell is borrowing a title from Schrödinger, who wrote a pair of articles (really, one article… Continue reading Yes Virginia, There Are Quantum Jumps

Finding Extrasolar Planets with Lasers

Cartoon representation of a frequency comb, from one of my papers.

On Twitter Sunday morning, the National Society of Black Physicsts account retweeted this: Using Lasers to Lock Down #Exoplanet Hunting #Space http://t.co/0TN4DDo7LF — ✨The Solar System✨ (@The_SolarSystem) September 28, 2014 I recognized the title as a likely reference to the use of optical frequency combs as calibration sources for spectrometry, which is awesome stuff. Unfortunately,… Continue reading Finding Extrasolar Planets with Lasers

Son of Interstellar Laser Communications

I didn’t plan to do a follow-up to yesterday’s post about the optics of sending messages with lasers, but then I starting idly thinking about detection, prompted in part by a bunch of conversations with my summer students about single-photon detectors. which led to scribbling on the back of an envelope, which led to Googling,… Continue reading Son of Interstellar Laser Communications

Interstellar Laser Communications

Lunar laser ranging beams launched from telescopes at the Goddard Space Flight Center (image from NASA http://www.nasa.gov/centers/goddard/news/topstory/2007/lsso2.html )

In the comments to yesterday’s grumpy post about the Fermi paradox, makeinu raises the idea that advanced aliens would be using more targeted communications than we do: On the point about electromagnetic communications: even we are now using lasers to target communications with space, because it’s simply more efficient and reliable. It’s also basically impossible… Continue reading Interstellar Laser Communications

Laser-Cooled Atoms: Ytterbium

Ytterbium metal, and artsy shot of a Yb MOT at JQI, and an electron shell diagram.

Element: Ytterbium (Yb) Atomic Number: 70 Mass: Seven “stable” isotopes, from 168 to 176 amu. Two of those are nominally radioactive, with half-lives vastly in excess of the age of the universe. Laser cooling wavelength: 399 nm and 556 nm. Doppler cooling limit: 690 μK in the UV and 4.4 μK in the green. Chemical… Continue reading Laser-Cooled Atoms: Ytterbium

Laser-Cooled Atoms: Cesium

L to R, cesium metal in a glass ampule, a college classmate working on a cesium cooling apparatus at Stanford, and an electron shell diagram.

Element: Cesium (Cs) Atomic Number: 55 Mass: One stable isotope, mass 133 amu. Laser cooling wavelength: 854nm, but see below. Doppler cooling limit: 125 μK. Chemical classification: Yet another alkali metal, column I of the periodic table. This one isn’t greyish, though! It’s kind of gold color. Still explodes violently in water, though. Other properties… Continue reading Laser-Cooled Atoms: Cesium

Laser-Cooled Atoms: Chromium

L to R: Shiny chromium bits, laser tables for the chromium trap in Paris, and an electron shell diagram.

Element: Chromium (Cr) Atomic Number: 24 Mass: Four “stable” isotopes between 50 and 54 amu. Chromium-50 is technically radioactive, with a half-life considerably longer than the age of the universe, so… Laser cooling wavelength: 425nm, but see below. Doppler cooling limit: 120 μK. Chemical classification: Transition metal, smack in the middle of the periodic table.… Continue reading Laser-Cooled Atoms: Chromium

Laser-Cooled Atoms: Lithium

L to R, lithium metal in paraffin, the red light for cooling lithium (from the LaserFest web site), and an electron shell diagram from wikimedia.

Element: Lithium (Li) Atomic Number: 3 Mass: Two stable isotopes, masses 6 and 7 amu Laser cooling wavelength: 671 nm Doppler cooling limit: 140 μK. Chemical classification: Alkali metal, column I in the periodic table. Yet another greyish metal. We’re almost done with alkalis, I promise. Less reactive than any of the others, so the… Continue reading Laser-Cooled Atoms: Lithium