Physics × Chemistry = Deciphering The Weird Quantum Glory Of Ultracold Gas

Physics, showing great potential in the quantum world and chemistry, revealing bizarre new possibilities for observation of quantum states study. Thinking about merging these researches, creates amazing new paths for study of such unimagined concepts. Researchers at UC Santa Barbara have now kept this imagination into motion, and deciphered the weird quantum glory of ultracold gas.

Researchers believe that this is not a minor breakthrough, but physicists have been trying for decades for linkage between quantum and classical physics. This study can possibly answer the disconnected areas of physics itself, like classical chaos theory, language for which is non-existent in quantum mechanics.   

Briefing what is Ultracold Gas: 

Simply, name defines itself. Gases or atoms maintained at temperatures close to zero kelvin are known as ultracold atoms or ultracold gases. To attain such a low temperature, several typical techniques are used and atoms are cooled to absolute zero temperatures. So why are scientists keen to study them?

Because, at such low temperatures, the quantum-mechanical properties of atom or molecule become vital. Such properties provide pathways for the study of fundamental particles, atoms and sub-atomic particles. In turn, provides foundation for the study of quantum chemistry, quantum physics, quantum technology and many more fields that can change the scenario of science and technology in the future.

Also, such systems are capable of creating exotic phenomenon like Bose-Einstein condensates. It also can open doors for research on simulation of condensed-matter systems, which are normally difficult to observe.

Bloch Oscillations: Building up the story

Before we head down to strangeness of behavior of Ultracold gases, lets simply understand what are Bloch Oscillations. (believe me. this is needed to understand things throughout the article.)

This is basically the phenomenon from solid-state physics. This branch describes how, atomic scale properties of a material can influence large scale properties of a material. Bloch oscillations define how a particle will react when kept in varying electric potential, under constant force. Also, particle is not just in any normal conditions but, must be confined to a periodic quantum structure.

So, Nobel Laureate Felix Bloch predicted that motion of particles kept under such conditions in a perfect crystal (as mentioned above), would be oscillatory.

However, this complex phenomenon is hard to observe in natural crystals, due to lattice defects. Interestingly, it has been observed in semiconductor super-lattices and in different Ultracold atoms in different ways.

Deciphering the topic and unwinding the strangeness:

While actually, these position-space Bloch oscillations were predicted nearly a decade ago, they were actually observed recently. For another bizarre, let me tell you something more interesting. In past couple of years, the concept of Bloch oscillations was taken to whole new level. By subjecting it to additional periodic force, scientists added time dependency on the oscillating system. Indeed, oscillations over oscillations – Super Bloch Oscillations – were discovered.

So, how is this related here? Why I discussed Bloch Oscillations?

Basically, researchers here took the Bloch system to one more step further. They have tried to change and modify the space lattice, where the atoms of gas interact. This was done in a simple way. They changed the lattice by varying the laser intensities and external magnetic forces, giving atom system a time dependency. Not only this, they also curved the interacting lattice, which created a non-homogeneous force-field.

Doing this, the motion of oscillations was slower downed, which gave them chance to observe minute things clearly. Also, this opened way on observing what happens to Bloch system, when kept in non-homogeneous force-field environment.

Unwinding weirdness using ultracold gas lead to uncommon results:

While performing the above things, some uncommon unpredictable results were seen. When observing the system researchers noticed that, the atoms shot back and forth, sometimes moving apart, sometimes creating unusual patterns. This was all in response to pulses of energy pushing on the lattice in different ways.

“We could follow their progress with numerics if we worked hard at it,” researcher David Weld said. “But it was a little bit hard to understand why they do one thing and not the other.”

When they tried interpreting the complex physics, they just saw mess because there was no such symmetry amongst the behavior of atoms.

To find a solution to this, researchers eliminated a dimension, here time. This was done by adopting a mathematical technique to observe classical non-linear dynamics. The mathematical phenomenon they used was – Poincaré Conjecture. 

In this experiment, time interval was set periodically modifying the lattice system. What they did was, over-looked the in-between times, and observed the behavior once every period. Naturally, results were seen. Beauty of physics and mathematics showed up. Proper symmetry was observed in shapes of trajectories of those atoms. Observing the system only at periods, based on this time interval, yielded something like a stop-motion representation of these atoms’ complicated yet cyclical movements.

These paths exactly explained why in some system atoms get pumped, while in others they break the wave function and spread out.

Breakthrough and Future:

One of the major breakthroughs that could be possible from this study on ultracold gas, is using this knowledge to engineer quantum systems. Quantum systems that can show amazing new behaviors with its applications in the most flourishing fields of science and technology, quantum computing.

Another view of this study, seeks answer to the emergence and future of quantum chaos. Quantum chaos is the study, where chaotic classical theories can be explained in terms of quantum theory. This can make understanding of Chaos theory possibly easy. At the same time, can potentially show some relation between quantum and classical theories of physics.

Most of us have heard of the famous Butterfly Effect. It is basic theory, which describes that, small change in one state of system, can result into large differences in later state. Thus, implies the dependence on initial conditions of the systems.

For information, this is part of classical of classical chaos theory.

Is this feature reproducible in quantum systems? Is it feasible? Feasible. Then to what extent?

It is really really puzzling to get same explanations in quantum theory from classical chaos theory. So, this may be a small piece of that part of research.

Confusion is a state of mind adopted to things either not understood, or not willing to be found.

Believe me; it is door to creativity of finding things which are obviously not obvious.

—OSD