In recent years, physicists have been dedicated to attaining control over chemical reactions in the quantum degenerate regime. This fascinating area of research focuses on understanding the behavior of particles when their de Broglie wavelength becomes comparable to the spacing between them. Theoretical predictions suggest that in this regime, many-body reactions between bosonic reactants will exhibit quantum coherence and Bose enhancement. However, validating these predictions experimentally has proven to be challenging.
Researchers at the University of Chicago recently conducted a groundbreaking study to observe and analyze many-body chemical reactions in the quantum degenerate regime. Their findings, published in Nature Physics, demonstrate the observation of coherent and collective reactions between Bose-condensed atoms and molecules.
Lead researcher Cheng Chin explains, “The quantum control of molecular reactions is a fast-progressing research area in atomic and molecular physics. People envision applications of cold molecules in precision metrology, quantum information, and quantum control of chemical reactions. Among all goals, quantum super-chemistry is a major science goal. Over 20 years ago, researchers predicted that chemical reactions can be collectively enhanced by quantum mechanics when reactants and products are prepared in a single quantum state.”
For years, scientists have been striving to achieve enhanced chemical reactions through quantum mechanical processes, often referred to as ‘super reactions.’ These super reactions bear similarities to superconductivity and the functioning of lasers, but involve molecules instead of electrons or photons.
The primary objective of Chin and his colleagues’ recent work was to witness these intriguing many-body super reactions in a quantum degenerate gas. To conduct their experiments, they utilized Bose-condensed cesium atoms, a highly electropositive and alkaline element commonly used in atomic clocks and quantum technologies.
Chin elaborates, “Cesium atoms are chemically reactive at low temperatures and can be converted into a molecular Bose condensate with high efficiencies. We monitored the dynamics of molecular formation in the atomic condensate and observed macroscopic quantum coherence between the atoms and molecules.”
The team’s experiments unveiled a range of captivating observations. They noted that super chemical reactions in the condensed cesium atoms led to the rapid formation of molecules, followed by oscillations at different speeds as the system moved towards equilibrium. Notably, samples with a higher density of atoms exhibited faster oscillations, indicating the presence of Bosonic enhancement in the reactions.
Chin remarks, “Our work demonstrates new guiding principles for chemical reactions in the quantum degenerate regime. In particular, we show that all atoms and molecules can react collectively as a whole. Such many-body reactions hold promises for advancing and reversing chemistry without dissipation and for steering reaction pathways towards desired products.”
Chin and his team’s recent work significantly contributes to the present understanding of quantum many-body chemical reactions. Their research outlines a viable approach to controlling these reactions at quantum degeneracy. In their paper, the researchers present a quantum field model that effectively captures the key dynamics of these reactions, guiding future experiments in this field.
Casting light on the team’s future plans, Chin states, “We now plan to identify new fundamental laws that govern chemical reactions in the quantum many-body regime. For instance, the condensed molecules are described by a single wavefunction, and the phase of the wavefunction may hold the key to controlling the direction of the chemical reaction. Additionally, we will investigate many-body effects in the reactions of more complex, polyatomic molecules.”
The quest for achieving control over chemical reactions in the quantum degenerate regime has taken a significant step forward with the recent study conducted by researchers at the University of Chicago. Through their experiments, they observed coherent and collective reactions between Bose-condensed atoms and molecules, shedding light on the potential for enhanced chemical reactions through quantum super-chemistry. This breakthrough paves the way for future investigations into quantum many-body chemical reactions, with the aim of harnessing their unique properties for precision metrology, quantum information, and quantum control of chemical processes.
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