How researchers tell different quantum excitations apart in individual molecules
Molecules can be placed in a wide variety of quantum states. How can these states be distinguished in measurements when theoretical models are unreliable? Which excitation process lies behind which measurement signal?
Researchers have discovered a method to distinguish different quantum excitations in individual molecules. Molecules can exist in various quantum states, but measuring and identifying these states can be challenging due to unreliable theoretical models. Arnab Banerjee, a researcher investigating cobaltocene molecules using tunneling spectroscopy, faced this challenge and collaborated with colleagues to develop a new approach.
The team used a scanning tunneling microscope to place cobaltocene molecules on a superconducting lead surface at extremely low temperatures. By manipulating the electrons and measuring the resulting current, the researchers obtained a spectrum revealing a variety of excitations. To differentiate between vibrational, spin, and orbital excitations, the team moved electrons into and out of the molecule and examined the impact of strong magnetic fields.
These methods allowed them to determine the energy at which excitations occur and their spatial distribution with submolecular resolution. Comparing the results to elaborate calculations confirmed the assignment of the measurement signals to the molecular states involved. This discovery could have significant implications for quantum computing, as molecules are quantum systems that need to be controlled at low temperatures.
Dr. Alexander Weismann, a co-author of the study, expressed optimism about the future of quantum research at Kiel University.
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