Final Report Summary - COMANCHE (Coherent manipulation and control of heat in solid-state nanostructures: the era of coherent caloritronics)
The Comanche project can be positioned in that broad realm which is represented by the overlapping of solid-state quantum physics, thermal physics, thermodynamics, nanoscience and nanotechnology, and commonly known as “caloritronics” (from the Latin word “calor”, i.e. heat).
Caloritronics, which is the branch of science dealing with the investigation of measurement, control, transfer, storage and conversion of heat at the nanoscale, can be considered the dual version of electronics, the latter indicating the branch of science and technology dealing with electric circuits.
Recently, the impressive advances reached in nanoscience and nanotechnology have enabled the realization of electronic nanodevices where quantum effects and coherence are exploited. In particular, in this domain electronic nanodevices have demonstrated to be versatile and effective systems to investigate further exotic quantum phenomena under controlled and adjustable conditions. Yet, these systems have shown the possibility to control the flow of charge with unprecedented precision, even at the level of single-electron accuracy. Although coherence typically plays a crucial role in determining the functionalities of these systems still little is known of its role in caloritronics. The present understanding of heat transfer and dynamics is hence much less satisfactory than the knowledge of charge transport.
The COMANCHE project has taken advantage of some new degrees of freedom and control offered by solid-state nanostructures joining superconductors (S), normal metals (N) and semiconductor two-dimensional electron gases (2DEG) at low temperature to tackle fundamental questions on quantum coherence and, more in general, correlation in an engineered solid-state environment in order to set the experimental ground for a new branch of science, i.e. the coherent caloritronics.
In particular, we have focused on heat (or energy) transfer and dynamics, and several related properties.
We aimed to create artificial structures where heat flow can be manipulated, controlled and directed over micron-scale distances through the use of the phase. We have explored original and totally novel approaches for the realization of thermal nanodevices such as heat transistors, heat rectifiers and splitters, refrigerators, and exotic quantum circuits which have taken advantage of the above-mentioned building-block structures in order to implement more specific functionalities, e.g. Josephson transistors or interferometers for sensitive magnetic-field detection with enhanced performance.
At the same time, understanding the physics of the proposed structures has given a unique opportunity to address fundamental heat- or energy-related phenomena such as coherent heat dynamics at the nanoscale, the possibility of heat interference, to investigate and establish the characteristic lengths for energy transport, time-dependent effects, and further issues related to fundamental topics like information and quantum thermodynamics in general. As COMANCHE is also tightly connected to the conceptual basis of decoherence, it is expected to be of high relevance for the understanding of the fundamental limitations existing in quantum information processing.
Experiments in Comanche relied on the use of some key-tools such as superconductors and normal metals to implement sub-micron-size structures operating at low temperature (i.e. typically below 1 K); the Josephson effect to allow phase-tuning of heat transferred by electrons; superconducting proximity layers which enable phase-dependent control of several electric and thermal key-properties, for instance, the electron thermal conductivity as well as the electron-phonon coupling; phase-tuning of the electromagnetic environment to master energy exchange between electrons and photons. There are many elements of novelty and strength in Comanche which lye in the choice of materials, experimental methods, device concepts, and basic scientific questions.
Caloritronics, which is the branch of science dealing with the investigation of measurement, control, transfer, storage and conversion of heat at the nanoscale, can be considered the dual version of electronics, the latter indicating the branch of science and technology dealing with electric circuits.
Recently, the impressive advances reached in nanoscience and nanotechnology have enabled the realization of electronic nanodevices where quantum effects and coherence are exploited. In particular, in this domain electronic nanodevices have demonstrated to be versatile and effective systems to investigate further exotic quantum phenomena under controlled and adjustable conditions. Yet, these systems have shown the possibility to control the flow of charge with unprecedented precision, even at the level of single-electron accuracy. Although coherence typically plays a crucial role in determining the functionalities of these systems still little is known of its role in caloritronics. The present understanding of heat transfer and dynamics is hence much less satisfactory than the knowledge of charge transport.
The COMANCHE project has taken advantage of some new degrees of freedom and control offered by solid-state nanostructures joining superconductors (S), normal metals (N) and semiconductor two-dimensional electron gases (2DEG) at low temperature to tackle fundamental questions on quantum coherence and, more in general, correlation in an engineered solid-state environment in order to set the experimental ground for a new branch of science, i.e. the coherent caloritronics.
In particular, we have focused on heat (or energy) transfer and dynamics, and several related properties.
We aimed to create artificial structures where heat flow can be manipulated, controlled and directed over micron-scale distances through the use of the phase. We have explored original and totally novel approaches for the realization of thermal nanodevices such as heat transistors, heat rectifiers and splitters, refrigerators, and exotic quantum circuits which have taken advantage of the above-mentioned building-block structures in order to implement more specific functionalities, e.g. Josephson transistors or interferometers for sensitive magnetic-field detection with enhanced performance.
At the same time, understanding the physics of the proposed structures has given a unique opportunity to address fundamental heat- or energy-related phenomena such as coherent heat dynamics at the nanoscale, the possibility of heat interference, to investigate and establish the characteristic lengths for energy transport, time-dependent effects, and further issues related to fundamental topics like information and quantum thermodynamics in general. As COMANCHE is also tightly connected to the conceptual basis of decoherence, it is expected to be of high relevance for the understanding of the fundamental limitations existing in quantum information processing.
Experiments in Comanche relied on the use of some key-tools such as superconductors and normal metals to implement sub-micron-size structures operating at low temperature (i.e. typically below 1 K); the Josephson effect to allow phase-tuning of heat transferred by electrons; superconducting proximity layers which enable phase-dependent control of several electric and thermal key-properties, for instance, the electron thermal conductivity as well as the electron-phonon coupling; phase-tuning of the electromagnetic environment to master energy exchange between electrons and photons. There are many elements of novelty and strength in Comanche which lye in the choice of materials, experimental methods, device concepts, and basic scientific questions.