Physicists Cool OH Molecules To Near Absolute Zero Through Evaporative Cooling

Researchers have created a process that can cool molecules to near absolute zero temperatures through evaporative cooling. Previous processes were then limited to ultra-cooling atoms.

Ultra cold atom physics deals with atoms that are at a temperature close to absolute 0 or 0 K (kelvins). In this field of science, temperature is measured at the nanoscale or at nano-kelvins (nK).

JILA researchers developed a new magnetic trap and a new technique to achieve "evaporative cooling" of hydroxyl molecules (one hydrogen atom bonded to one oxygen atom). A microwave pulse at a specific frequency converts hot molecules inside the trap to a slightly different energy state. A small electric field is pulsed on briefly to destabilize and eject these converted molecules from the trap. As the microwave frequency is slowly altered, molecules distributed inside the trap (which has a varied magnetic field strength) are progressively converted and removed from the top of the trap, where molecules are hotter, to the bottom, where molecules are cooler.
Credit: Baxley and Ye Group/JILA

Since it is impossible to bring an object to absolute zero (as stated in the Third Law of Thermodynamics), ultracold atom physics study objects that are close to absolute zero. The coldest an atom has been brought down to is 0.45 nK (nano kelvin) or 4.5 x 10^-10 K or 0.00000000045 K.

At these levels, atoms start to behave differently and their properties start to move from classical physics to quantum mechanics.

A property that scientists are interested in is the transformation of atoms into a new form of matter called the Bose-Einstein Condensate (BEC). The Bose-Einstein condensate happens when atoms that are brought down to near absolute zero start to behave like waves rather than particles.

As the temperature goes down, these atoms start to vibrate in the same wavelength. Because of this, they start to behave like a single mass object, the Bose-Einstein condensate.

Laser cooling and evaporative cooling are the two ways that scientists use to lower the temperature of atoms. Laser cooling in simple terms uses laser light on atoms to manipulate photons to lowers the energy level of the atom

With evaporative cooling, atoms with higher energy levels (temperature) are ejected out of an optical or magnetic trap until only atoms with the lowest energy levels are left. BECs and ultracold atoms are at very low temperatures are highly sensitive to heat (2nd Law of Thermodynamics).

Practical applications of ultracold atom physics range from super sensitive sensors to atom chips used in diodes and semiconductors. Current technologies used by magnetic levitation (mag-lev) trains, quantum computers and MRI devices utilize principles behind ultracold atom physics.

Light Pulses From Quark Gluon Plasma To Accurately Measure Time in Septillionths of a Second

Scientists have proposed using the light pulse emitted by a quark gluon plasma, a newly discovered state of matter, as a way of measuring time at precise levels of yoctoseconds which is a septillionth of a second (1x10^-24).

A quark gluon plasma (QGP) is a new state of matter that results from the collision of two nuclei. It is made up of two of matters building blocks, the quark and the gluon.

The image illustrates two lead atoms colliding to form a quark gluon plasma which in turn emits a short light pulse.

Quarks and Gluons

Quarks are one of the tiniest building blocks of matter. The proton and neutron inside an atom are made up of these quarks. A particle made up of quarks is called a hadron. Particles made up of quarks are called hadrons.

Ultra Cold Atom Physics Experiment Delves Deep Into Bose-Einstein Condensates

Ultra cold atomic physics is a field of quantum mechanics. It deals with the observation and experimentation of atoms that are brought down to a temperature close to absolute zero.

To cool down these atoms, scientist uses two techiques, laser cooling and evaporative cooling. Atoms in an optical or magnetic trap are subjected to the cooling process and the hotter atoms are ejected from the trap leaving in the ultra cooled atoms.

Since it is impossible to lower the temperature of an object to absolute zero (as stated in the 3rd law of thermodynamics), atoms are cooled down as close to absolute zero as possible (1 nanokelvin). In 2003, MIT Researchers achieved the lowest temperature which is .45 nK (nano kelvin) or 4.5 x 10-10 K or 0.00000000045 K.

A fundamental principle of cold atom physics is the Bose-Einstein Condensate. This is a property of ultra cold atoms where they merge together and form a new form of matter. The underlying principle here is that when subject to ultra low temperatures, atom which behaves as particles, will start to manifest more wave-like properties. Ultimately, all other surrounding atoms will start to vibrate at the same frequency or have the same wavelength, forming one single mass - the Bose-Einstein Condensate.

Cold atom physicsand quantum mechanics have lots to offer in real world applications. Mag-Lev (Magnetic levitation) trains, quantum computers, and even Magnetic Resonance Imaging (MRI) use its basic principles.

Experiment in University of Florida laboratory corrects prediction in quantum theory

An international team of scientists is rewriting a page from the quantum physics rulebook using a University of Florida laboratory once dubbed the coldest spot in the universe.

Much of what we know about quantum mechanics is theoretical and tested via computer modeling because quantum systems, like electrons whizzing around the nucleus of an atom, are difficult to pin down for observation. One can, however, slow particles down and catch them in the quantum act by subjecting them to extremely cold temperatures. New research, published in the Sept. 20 edition of the journal Nature, describes how this freeze-frame approach was recently used to overturn an accepted rule of thumb in quantum theory.

"We are in the age of quantum mechanics," said Neil Sullivan, a UF physics professor and director of the National High Magnetic Field Laboratory High B/T Facility on the UF campus -- home of the Microkelvin lab where experiments can be conducted in near-absolute zero temperatures. "If you've had an MRI, you have made use of a quantum technology."

The magnet that powers an MRI scanner is a superconducting coil transformed into a quantum state by very cold liquid helium. Inside the coil, electric current flows friction free.