Quantum phononics with 2D materials

Lead Research Organisation: University of Cambridge
Department Name: Physics

Abstract

This PhD will develop a device for coupling light (photons), matter (spins) and motion (phonons) using transition-metal-dichalcogenide (TMD) monolayers. Such a device would provide the basic building block for preparing and controlling arbitrary quantum states of phonons; enabling different quantum systems to be connected via a phonon bus - overcoming a major problem facing the implementation of quantum-based computing and implementing quantum-assisted force sensing. The student will aim to develop freely suspended TMD mechanical oscillators (MOs) with high mechanical quality-factors (a vital pre-requisite for creating phonons with high quantum coherence) and probe their mechanical properties. This would open up the unique and exciting prospect of coupling phonons with optically active quantum emitters (these are essentially "artificial atoms") hosted within TMDs that the group has been recently exploring.

Planned Impact

Our vision is to take graphene from a state of raw potential to a point where it can revolutionise flexible, wearable and transparent (opto)electronics, with a manifold return in innovation and exploitation. Such change in the paradigm of device manufacturing may revolutionise the global industry. The importance of graphene was recognised by the 2011 statement of the Chancellor of the Exchequer launching the initiative that lead to the funding of the Cambridge Graphene Centre, where the proposed Graphene Technology CDT will be based. The aim is take graphene and related materials from "the British laboratory" to the "British factory floor". Not only does our vision align with this mandate, but it also exploits and strengthens several key areas of national importance where the UK has recognised excellence, such as printed electronics, energy and RF & Microwave Communications. Thus, we will strive for both economic impact, by stimulating new UK-manufactured high-value products, and societal benefits, by utilising graphene in potentially many areas including security, energy efficiency and quality of life.
The beneficiaries of our proposal will be of course the cohorts of students that will be trained every year, but will extend more widely. Considering the private sector, we have already indentified tens of companies that will benefit from our work. To achieve the final goal of graphene-technology, and to ease the transition to commercialisation, we have strong alignment with industry needs and engage them as project partners of the CDT: Dyson, Novalia, Plastic Logic, Nokia, Toshiba, BAE Systems, Aixtron, PEL, Nanocyl, IdTechEx, Philips, Dupont, CambridgeIP, Polyfect, Agilent, Nippon Kayaku, Victrex, IMEC. Many more are also partnering with the Cambridge Graphene Centre, and even more are expected to join and benefit directly or indirectly from our work. We consider the civilian sectors of healthcare, telecommunications, energy and homeland security to be those in which applications based on graphene can make significant impact on society at large. There are also applications in defence, especially in secure communications and radars. This will foster competitiveness and enhance quality of life. In particular, the proposed CDT will be of prime interest to industries dealing with the following devices and applications: 1. Mobile communications, wireless sensor networks, including wearable devices. 2. Nano-structured materials for light and microwave energy harvesting. 3. Active and reconfigurable microwave, terahertz and optical materials, including advanced antenna applications for radar and communications.
Policy-makers, within international, national, local government will also benefit. If the vision of graphene as the material of the 21st century is fulfilled, there will be a need for its properties, benefits, applications and advantageousness compared to current technology to be known by the relevant public bodies. For example, any new policy on energy saving, or mobile communications may need to include a reference to the benefits, or limitations, of graphene-based devices.
Economic resilience and innovation require post-doctoral researchers and students trained in new areas. We will contribute to increasing the talent pool for the future graphene industry. The proposed doctoral training centre will provide unique training to students in various aspects of graphene technology: from graphene nanotechnology to energy, RF/microwave and (opto)electronics. This will develop many skilled researchers over the project lifetime, who will stimulate the sustainability of UK graphene engineering research and future commercialisation opportunities across a variety of sectors.

Publications

10 25 50
 
Description I have developed a method for reliably suspending large numbers of WSe2 monolayer resonators on silicon nitride TEM grids with 2.5 and 5 micrometer holes.
I have also developed an interferometer capable of reliably and easily measuring thermal motion at room temperature of monolayer WSe2 resonators without relying on absorption to do so.
Exploitation Route Both of these methods could be used by other groups to expand the types of resonator designs used in monolayer resonator research, as they allow the suspending of and measurement of monolayer resonators on many substrates that could previously not be used. This is useful as it opens the way for using samples with phononic crystals, strain control etc.
Sectors Electronics

 
Title Fabrication method for suspension of monolayer WSe2 on various substrates. 
Description I use a modified exfoliation and transfer method to produce large hundreds of micrometer scale monolayers of WSe2 which I then transfer onto structures with holes in them in order to suspend the WSe2 in a clean and reliable way over the surface. 
Type Of Material Improvements to research infrastructure 
Year Produced 2022 
Provided To Others? No  
Impact This fabrication method has allowed me to fabricate WSe2 monolayer resonators on almost any substrate and with large enough numbers of clean, intact resonators to do statistical analysis over tens of resonators. This massively increases the number of resonator designs we can investigate, while being able to do them quickly and easily. 
 
Title Interferometer method to detect nanomechanical motion of suspended material using pure reflection. 
Description The method I have developed allows us to measure the thermal mechanical motion of WSe2 monolayer resonators using reflected light from the surface and without relying on any cavity effect, driving method or other sample design to take the data. 
Type Of Material Improvements to research infrastructure 
Year Produced 2021 
Provided To Others? No  
Impact This method allows for the analysis of monolayer resonators on a wide range of substrates and resonator designs, as we are not limited by needing a particular cavity interaction and are sensitive enough to not require a driving mechanism. This opens up the potential to study monolayer material strain engineering, damping mechanisms, phononic crystals and more. 
 
Description Monolayer resonators in phononic crystals 
Organisation University of Copenhagen
Country Denmark 
Sector Academic/University 
PI Contribution The collaboration Albert Schliesser is intended to investigate the impact of using phononic crystals to try and reduce mechanical losses in WSe2 monolayer membranes. I ave developed the method for suspending monolayers on the phononic crystals and the detection method for observing their motion.
Collaborator Contribution My partners have designed a phononic crystal for us to use and started the process of fabricating them for us to use.
Impact So far non as the collaboration has only just begun.
Start Year 2022
 
Description NV magnetic 2D materials 
Organisation University of Cambridge
Department Cambridge Neuroscience
Country United Kingdom 
Sector Academic/University 
PI Contribution I fabricated a set of magnetic materials, which have not been studied in the UK before. I did this using my extensive experience in 2D material and heterostructure fabrication. I also made use of my access to the Cambridge Graphene center facilities to make these samples.
Collaborator Contribution My collaborators used an NV center setup to map out the local magnetic field of the samples, as well as carrying out AFM on them to help with characterization.
Impact The outcomes have been the development of methods to fabricate the materials used and the data gathered from individual multi and monolayer samples as well as samples with interfaces between two different magnetic 2D materials.
Start Year 2021