We will talk about Quantum Sensor but (In order to get a detailed understanding of the surface of a material, scientists need to use nanoscale scanning tunneling microscopes. One technique they have discovered is using hydrogen molecules, but as H2O has two hydrogens and two oxygens, it can be difficult for these molecules to stay away from oxygen atoms.
Physicists at the University of California, Irvine, have shown the use of a hydrogen molecule in a laser-equipped scanning tunneling microscope. This sensor can measure the chemical properties of materials and is thus gaining importance within that industry.
Using this technique, researchers can see the inside of materials in a way that was previously impossible. It could also have applications in energy systems, electronics, and quantum computers.
Researchers in UCI’s Department of Physics & Astronomy and Department of Chemistry have found that atoms of hydrogen can be situated between the tip and surface. This is a significant change in our understanding of how these kinds of molecules are oriented. The scientists were able to have a laser pulse stimulate the hydrogen molecule at cryogenic temperatures and in an ultrahigh vacuum environment of the instrument, which makes them able to detect changes to quantum states.
“The results of this project represent an advance in both the measurement technique and scientific question the approach allowed us to explore,” said Wilson Ho, a member of the research team. “Here’s a great article about quantum mechanics and how they are the basis behind what makes these microscopes so special. Newer models of this device, such as those in the article, are more efficient and can act upon certain images more quickly.
Ho said that the hydrogen molecule is an example of a two-level system because its orientation shifts between two positions, up and down, and is slightly horizontally tilted through a laser plate, scientists can demonstrate the superposition of two different states. The system’s state will cyclically be excited to the ground and back resulting in a short-lived superposition. The decay time of these cycles is very short at just a few picoseconds, but the scientists were able to measure it & use this information to learn more about how molecules in a liquid can interact with each other.
The Electron Microscope
“The hydrogen molecule is where the quantum microscope comes into play,” said Ho. ‘It’s more integral to the instrument than just being there as part of its “The electron microscope allows us to view the sample under a resolution of 0.1 angstroms. This is detailed enough to show how the charge distributions change on the sample at this level.”
The space between the sample and the STM tip is incredibly small, about 0.6 nanometers. The newly-assembled STM that Ho has built can detect the presence of hydrogen and elements. The team tested it with success to create spectroscopic readings. This experiment can mark the first time in chemical spectroscopy that a single-molecule sensor has been demonstrated. Previously, these kinds of sensors required multiple antennas or other methods which would have to be repeated for each molecule. Terahertz radiation is able to easily penetrate through a single chemical and measure it more accurately than previous methods.
The development of hydrogen as a gas is difficult for us because, in its liquid state, it will form bubbles without external pressure. It is only when the amount of available surface area becomes very small that hydrogen can move freely and maintain its quantum coherence in low-pressure regions like catalysts. It would be interesting to see what other applications this discovery has.
“Hydrogen can characterize a material by observing its electrostatic field distribution,” said study lead author Likun Wang. “In principle, it is possible for electrodes to carry one or more catalysts that support hydrogen-adsorption reactions.”
Joining Ho and Wang on this project was a UCI graduate student in physics and astronomy, Yunpeng Xia.