Chemistry has always been a field dominated by the principles of classical physics, but recent research by US scientists has unveiled a groundbreaking phenomenon known as “quantum superchemistry.” This extraordinary achievement demonstrates how ultracold atoms can undergo chemical reactions at an accelerated rate. While the idea behind this phenomenon was theorized over two decades ago, it is only now that we are witnessing its empirical confirmation on such a scale.
One of the key challenges in observing superchemistry, which involves the collective behavior of numerous atoms, is the requirement for experiments to be cooled to extremely low temperatures approaching absolute zero. According to Cheng Chin, a physicist at the University of Chicago, the temperature needs to be around 10nK, which can be relaxed with a higher number of particles involved.
Chin and his colleagues successfully achieved supercooling of a gas consisting of caesium atoms, leading to the formation of a Bose-Einstein condensate (BEC). In this state, the caesium atoms function collectively as if they are in a single quantum state. By applying a magnetic field to the BEC, the researchers stimulated a chemical reaction in which caesium atoms bonded to create caesium molecules.
In classical chemistry, the formation of molecules occurs over time as atoms collide with each other. The rate of these reactions depends on the concentration of atoms and numerous other factors. However, in this recent experiment, the supercooled caesium atoms within the BEC remarkably formed caesium molecules simultaneously, exhibiting a significantly accelerated reaction rate compared to classical conditions. For instance, in an experiment involving a few thousand atoms, the reaction rate increased by three to five times. This research also revealed that the more atoms present in the BEC, the faster the reaction occurs.
University of Chicago’s website quoted Chin: “You are no longer treating a chemical reaction as a collision between independent particles, but as a collective process… All of them are reacting together, as a whole.”
This newly observed phenomenon contradicts another known effect of BECs, where chemical reactions between ‘fermionic’ atoms are suppressed. Peter Krüger, a physicist from the University of Sussex, explains that fermionic atoms always have an odd number of constituent particles, while bosonic atoms like caesium have an even number. The enhancement of thermodynamics with bosons in this context is an intriguing realization that introduces a new class of phenomenon.
While physicist Wolfgang Ketterle from the Massachusetts Institute of Technology notes the existence of a 2000 paper reporting evidence of quantum superchemistry, he emphasizes that the recent work is distinct and surpasses previous studies. Ketterle, a recipient of the 2001 Nobel Prize in physics for his contributions to BECs, expressed his enthusiasm for the project’s advancements.
The Chicago team also discovered that individual caesium atoms can be “primed” to produce caesium molecules with identical molecular states, each possessing unique physical and chemical properties. Chin acknowledges that further exploration is required in this area. In classical chemistry, molecular states are randomly determined, but in the realm of quantum superchemistry, it appears that specific states can be selected.
Chin emphasizes the enormous potential of this research, not only in terms of faster reactions but also in the controlled formation of specific molecular states. Future investigations will focus on understanding and manipulating these molecular states, as well as expanding the range of substances to more complex molecules.
While the possibility of quantum superchemistry impacting fields like quantum computing holds promise, Chin cautions that the current experimental setup is far too complex to be practically applied. For now, this remarkable discovery remains at the forefront of fundamental research, paving the way for new insights into the intricate world of quantum chemistry.
What is quantum superchemistry?
Quantum superchemistry refers to a phenomenon where ultracold atoms undergo chemical reactions at an accelerated rate compared to classical conditions. It involves the collective behavior of numerous atoms and requires experiments to be conducted at extremely low temperatures near absolute zero.
What is a Bose-Einstein condensate (BEC)?
A Bose-Einstein condensate is a state of matter that occurs when a group of bosonic particles, such as caesium atoms, cools to a temperature close to absolute zero. In this state, the particles behave collectively as if they occupy a single quantum state.
How does quantum superchemistry differ from classical chemistry?
In classical chemistry, chemical reactions occur as a result of collisions between independent particles. However, in quantum superchemistry, the reaction process is considered a collective phenomenon, with all the particles reacting together as a whole.
What are the potential applications of quantum superchemistry?
While the current experimental setup is too complicated for practical use, quantum superchemistry may have future applications in fields such as quantum computing. Further research is needed to fully understand and harness the potential of this phenomenon.