Periodic Reporting for period 3 - MolecQuantumMachines (Molecular Quantum Machines)
Reporting period: 2023-02-01 to 2024-07-31
While quantum effects are already demonstrated in electronics and optics with the promise for future quantum electronics and quantum computing revolution, similar advances towards quantum machines and quantum energy converters are still in their infancy. This is due to inherent complications in fabricating, monitoring, and controlling such devices. In 1977 Aviram and Ratner suggested that a single-molecule can act as a diode when it is embedded between two electrodes. Such single-molecule junctions cannot be used as actual electronic components in mass production. However, they have become a versatile testbed for fundamental studies at the frontier of science, allowing a better understanding of nanoscale electronics, spintronics (spin based electronics), and heat dissipation at the nanoscale. In this initiative, we are using single-molecule junctions as quantum machines. Based on our lab experience with fabricating, analyzing, and controlling the structure and functionality of molecular junctions, we aim to reveal the properties of machines and energy conversion at the ultimate limit of miniaturization. We expect that this effort will pave the way for the use of miniaturized machines and open the door for new schemes for economic energy conversion.
In our first project, we have fabricated a single molecule motor based on current induced forces, demonstrated its operation, and currently, we study its properties and potential applications. In a second project, we have identified and study the Chiral Induced Spin Selectivity (CISS) effect in molecular junctions, and in the second phase of this project we intend to use it for magnetic control over thermopower. In a third project, we developed and built a new experimental setup that will allow us to explore electron-vibration interaction and heat pumping in molecular junctions. In a forth project, we study the conversion of mechanical work to heat at the atomic scale and already found such an effect in atomic junctions. During the described work, we unexpectedly reveled several unknown phenomena that include a quantum version of flicker noise (published in Physical Review Letters in 2022), and the ability to efficiently tune the structural properties of atomic wires by magnetic fields (published in Nature Communications in 2022).
In the framework of this initiative we had several unexpected exceptional findings. Here, we briefly highlight two recently found phenomena. We identified a quantum form of electronic flicker noise that contains valuable information on quantum conductors. This noise is experimentally studied in atomic and molecular junctions, and theoretically analyzed considering quantum interference due to fluctuating scatterers. The identified form of flicker noise uniquely depends on the distribution of transmission channels, which are a central characteristic of quantum conductors. This dependence opens the door for the application of flicker noise as an accessible probe for fundamental properties of quantum conductors and many-body quantum effects (Phys. Rev. Lett. 2022). When the dimensions of materials are reduced to the nanoscale, magnetic properties can emerge as a result of structural changes. Recently, we found the inverse effect, where the size and direction of applied magnetic fields affect the structural properties of nanostructures. Specifically, we have found that parameters such as interatomic distance, formation probability, and the stability of metal and metal-oxide atomic wires can be tuned by magnetic fields, paving the way for magnetic control over material properties at the atomic scale (Nature Commun. 2022).
In view of the initial technological developments and scientific progress, we are now ready for the next phase of this initiative. In particular, we will finalize the analysis of our single molecule motor, mapping the parameters that control the operation of such a nanoscale motor. We intend to demonstrate magneto-thermoelectric effect in our chiral molecular junctions in order to achieve magnetic control over thermopower in nanoscale devices. In another project, electron vibration interaction will be used to gain heat pumping in molecular junctions, using a specially-made setup we have built. Finally, mechanical work to heat conversion - a process that is central for any mechanical device - will be characterized at the limit of miniaturization, in atomic scale junctions.
In view of the initial technological developments and scientific progress, we are now ready for the next phase of this initiative. In particular, we will finalize the analysis of our single molecule motor, mapping the parameters that control the operation of such a nanoscale motor. We intend to demonstrate magneto-thermoelectric effect in our chiral molecular junctions in order to achieve magnetic control over thermopower in nanoscale devices. In another project, electron vibration interaction will be used to gain heat pumping in molecular junctions, using a specially-made setup we have built. Finally, mechanical work to heat conversion - a process that is central for any mechanical device - will be characterized at the limit of miniaturization, in atomic scale junctions.