The Coldest Thing You've Ever Seen

December 12, 2008

by William McGehee

Where is the coldest place in the universe? Siberia? Deep space? Not even close. In vacuum chambers around the world, atomic physicists use clever arrangements of magnetic fields and laser beams to trap dilute clouds of atoms and cool them to ridiculously cold temperatures only a few billionths of a degree above absolute zero. To give you an idea how cold this is, consider that deep space is a balmy 2.7 Kelvin or -454.8 degrees Farenheit.

One of the interesting properties of these gases is that you can see them with the naked eye. The inset picture shows a glass vacuum chamber with an ultra-cold blob of rubidium atoms in its center. The laser beams used to confine and cool the gas interact strongly with the hotter atoms while ignoring the colder ones to produce what is aptly named optical molasses. The lasers used in this process lie in the red part of the spectrum, so the atom cloud naturally appears reddish in color.

The rubidium cloud pictured has a temperature around ten millionths of a degree above absolute zero and is almost certainly the coldest thing you have ever seen. It seems kind of strange that something this cold would not instantly solidify, but the density is so low that this is not possible. The rubidium cloud contains about a billion atoms whereas the same volume of air would contain about a billion times more atoms and a normal solid a million times more atoms still.

You get the idea--the gas is crazy cold and there are not many atoms. So, what are they good for?  These ultra cold gases were originally created to study a novel form of matter called Bose-Einstein condensate in which all of the atoms are so cold that they move in lockstep with each other. It was an incredible feat when this new state of matter was first created in 1995, but now these gases are used mainly as tools to study a number of phenomena.

The group I work for takes these condensates and loads them into an optical lattice, this is just an array of interfering laser beams used to create a periodic array of little wells in the gas. When these wells are prepared properly, just a few of the atoms will sit in each well, and the system as a whole will behave like a normal crystal. This opens an incredible number of possibilities for understanding materials. In traditional material science, powerful microscopes are used to look at a surface of atoms, but as the saying goes, that is just scratching the surface. Our crystal of ultra cold gases are much more dilute than normal materials, and we can actually look inside them to study materials in the bulk.

It turns out that the crystals made with an optical lattice are actually more perfect than those that exist in nature. You would think this would be great, but everything in the real world has imperfections and a lot of interesting phenomena arise from have these imperfections. The novel thing my lab does is introduce a small level of disorder into the optical lattice to simulate the disorder in traditional systems. With this you can emulate a number of interesting material properties such as superfluidity and high-temperature superconductivity and learn how disorder affects these systems.
_________________________________________________________________________________________

William McGehee is a physics graduate student at the University of Illinois where he simulates materials using ultra cold atomic gases. He is part of the DeMarco research group that specializes in adding disorder to ultra cold quantum systems.

Comments

[Nike Running Shoes]

nice!

[Nike Football Shoes Wholesale]

i like this design!

[Nike Football Shoes Wholesale]

i like this design!!!

[Phil]

Cool! Well, cold actually :)

[darkfall gold]

Nice post. This post is different from what I read on most blog. And it have so many valuable things to learn. Thank you for your sharing!

[Electronics wholesaler]

Inventory Source is dedicated to not only helping its members find trusted wholesale product sources, but we also want to provide them with new opportunities for places where they can promote or sell their products.

[JesselliCouture]

Buy Front and back embroidered tote bag, with scalloped edge detail. Light weight and easy to carry, removable faux suede finish contrast colored pouch inside from Jesselli Couture Wholesaler Handbags.

[logobuy]

Custom Banners & Custom Vinyl Banners in full color and ready made banner signs printed and delivered fast for business or personal use ready for indoor or outdoor advertising in trade shows.

[Honor Mansion]

Healdsburg resorts grounds in Healdsburg inn in the beautiful Sonoma Wine Country. Its grounds include a putting green, a swimming pool and croquet, bocce ball, basketball and tennis courts.

[Sunsweet]

ORAC (Oxygen Radical Absorption Capacity)- A measure of each food’s ability to neutralise free radicals and protect the body from ageing, heart disease, cancer and other degenerative conditions.

[Hotel Akros]

Akros Hotel - Provides best services like accommodation in Quito Ecuador, meeting rooms, honeymoon suite, executive suites.

[Online backup]

We provide online backup & data recovery solution for natural disaster or fire & protect your valuable data with the help of Online Hosted Application Service & Digital Lock Down and Recovery Service.

[family therapy]

Family therapy is therapy for three or more family members. Toronto therapists offer psychotherapy, functional family therapy & child play therapy

[Red de concesionarios Mitsubishi]

Contacte y envíe sus comentarios a cualquiera de nuestros distribuidores Mitsubishi y adquiera información acerca de nuestros carros en venta como nuestro nuevo modelo de Lancer.

[law]

Our family law attorneys are attentive to the emotional, psychological, and financial issues created by a divorce. We assist families in martial settlement agreements and resolve there issue by a divorce

[gates]

Fencing and Gates has its designing and manufacturing facilities in the UK. We ensure that we maintain the highest production quality in metal gates, wooden gates, garden arches, decking panels, and gate measuring

[clampon, accessories, marine]

Get the latest & most updated clamp-on accessories, marine lighting, motor brackets, rod bushings, boat ladder, boat leaning post, and boat upholstery at affordable and reasonable rates.

[Private money lenders]

We are recognized as a leading force in the real estate financial services industry, providing professional and reliable services backed by integrity. Our mission is to provide the best solutions and complete satisfaction to our reputed clients

[Free moving estimate]

When it comes to commercial as well as residential relocation services, we are the best. With years of experience behind us, we understand the importance of privacy. We do not share your information with any other company, agency, or individual.

[Marital Therapy]

Marital therapy, or couples counseling is a therapeutic process where both couples come to the same therapy session to work on their problems together with guidance from a professional marital therapist. You can select the best therapy for your marriage problems.

[Arabian Nights,Disney packages]

Looking for an awesome vacation? We offer tremendous places for vacations and other activities. We specialize in dinner shows like Arabian nights with some of the most exquisite horsemanship which will make your night most memorable

[Custom Home Builder New Jersey]

We create the best possible homes for you within your budget. Before starting the project, we provide complete information and make proper plans and strategies to build your home.

[Home Security Systems]

Channel Vision provides IP cameras and IP camera solutions for your security needs. Our surveillance & balun solutions include high resolution IP, bullet, dome, PTZ indoor & outdoor cameras, web servers & an entire line of MPEG4 DVRs.

[Hair Remover]

Our products help prevent unwanted hair growth without the need of waxing, tweezing, laser, or even electrolysis