Sketching the Future of Quantum.
Welcome! This is a personal blog of a guy fascinated by quantum many-body sciences and its technological applications to the human society.
Self-portrait.
Who am I and what is this blog about.
Physics
I am currently a researcher in experimental physics in the field of condensed matter physics. I used to study theoretical condensed matter physics but now I work on the cryogenic electronic experiments of it as professional.
Engineering
I prefer to call myself an engineer rather than a scholar. I aim to engineer what I get in the lab to make real technological impact to the society. I am interested in building the bridges from solid state physics to quantum nanoelectronics.
Mathematics
Theories used to be my best friend. I used to enjoy learning fancy mathematics, but now treat them as tools and puzzle games, such as abstract algebraic tools in quantum many-body theory. Interestingly, some of them are very useful to real world experiments.
Computer Sciences
As a CS amateur, I keep writing different codes & algorithms in my work from scratches to scripts to make the theories executable and processes automatic. I enjoy developing software interfaced with experimental hardware.
Philosophy
In the end, the whole structure of my thoughts and actions are built consistently within my philosophical system: a materialistic, constructivistic and socialistic ideology.
Literatures & Others
Reading literatures & humanities & history is my great hobby to escape from the cruel reality in life. Unlike the instrumental rationality, there is never an absolutely rationality of living our own lives.
World views and interests.
During my life, I try to understand and change the universe from my own perspectives.
My world views are deeply rooted in three questions: who am I, what is the nature/society around me, and how can I do to make it a better place.
The first question lies down the philosophical foundation of my values. I am definitely not a pure technologist who only cares about cold rationality or a theorists who only follows him/her personal interests. I am a human-being at the first place, and all questions I/we have go down to a self-question about myself/ourselves, then expand into a willingness to reform the outside world.
The second question guides me to explore and understand the nature and the society as deep and extend as possible. Physics is the way I follow to study the natural world with first principles. Philosophy and sociology provide me with ideologies to understand the social beings surrounding me.
The third question leads me to use what I learnt from myself (my self-knowledge) and what I learnt from the outside (natural sciences and social sciences) to change the world. This requires not only theories, but very pragmatic technical engineering works. This is what I am learning and doing now.
All of the values above, the knowledge they involve and the experience they relate, boil down to my current professional interests:
- Condensed matter and quantum many-body sciences. The discovery of quantum mechanics has ushered the great improvement of the understanding to the microscopic world for human beings. The quantum theory of a single particle or several particles i.e. the theory of atoms, are mostly constructed and developed well in the 20th century by the fathers of quantum mechanics and the following particle physicists. Over the last 100 years, the theory of weakly interacting particles are more or less well understood, which is consolidated into the so-called standard model within the modern quantum field theory. Yet, it turns out that the refined knowledge of a single particle does not lead to a complete knowledge of the organization of many particles and the phases they form in our macroscopic world, in a word, the knowledge of atoms does not naturally imply the knowledge of the materials they form. This is where the reductionism fails, but the emergentism starts showing its power. Following Lev Landau, P. W. Anderson and other great physicists’ footprints, modern materials sciences has now become a great sea of condensed matter physics, featuring profound new physics ranging from the principal of symmetry breaking to the emergence of topological invariants inside a many-electron system. I am fascinated about these interesting quantum many-body sciences, especially those phenomena that cannot be explained by single-particle theory i.e. strongly correlated electrons, such as high-Tc superconductivity, fractional quantum Hall effect, and Kondo physics.
- Quantum transport and microelectronic experiments. There are many interesting quantum many-body theories nowadays that are beyond the weakly interacting Landau paradigm of many-body electrons. There are also many powerful experimental tools to detect the collective quantum many-body behaviors of quantum materials. In some of the cases, they can crosstalk with each other in a rather complicated but still efficient way. Yet in some of the cases, people from each side cannot understand other better due to the growing complexity of the quantum many-body study. Yet, the most direct, clean and powerful experimental method to probe the strongly correlated electronic structure and to be able to communicate with modern condensed matter theories to-date is the quantum transport method. All of the direct evidences of superconductivity, quantum Hall physics or Kondo effect, which, leads to the formation of BCS theory, topological electrons or renormalization group theory, come from the direct quantum transport measurement of the electron resistance inside a solid. Moreover, modern quantum transport experiments do not only confined to simple DC four-probe measurement, but can be coupled to mature microelectronic engineering technologies, such as analog, RF or digital integrated circuits. The latter is another world that involves electrical engineers and the history of the modern microelectronics. In short, profound theories to test and develop, direct experiments to perform, and rich engineering tools to use. Hence, I am fascinated about these electronic-transport-based experimental techniques and the microelectronic engineering as well as modern VLSI circuit design.
- Programmable correlated electrons inside two-dimensional materials. The first two aspects build up my general experimental physical interests and engineering routine to realize the corresponding theories. The platform I am looking into is the atomically thin two-dimensional materials, in particular, a family of two-dimensional transition metal dichalcogenides (TMDs). These novel few-layer semiconductors or superconductors are exotic materials platform hosting naturally formed strongly correlated electrons due to their d/f-orbital nature, high effective mass and large spin-orbital coupling, and with great electronic tunability due to the atomic semiconductor-like properties. More interestingly, once two or more monolayer TMDs are artificially twisted, these homo- or hetero-multilayers can form moire superlattice with flat bands, a breeding ground of strongly correlated electrons due to nearly zero kinetic energy of interacting electrons. Unconventional superconductivity, fractional quantum anomalous Hall effect, and topological Kondo insulators, three of the long-term topics in condensed matter physics community have all been observed through dedicated transport measurement in different kinds of 2D moire TMD systems. Particularly, these 2D TMDs can be fabricated into regular transport nanodevices just like modern Si MOSFETS, with tailored yet novel fabrication techniques involved. This device integration capability greatly enhances and diversifies the electronic tunability of the delicate electronic structures inside these quantum materials. My long-term goal is to fulfill a programmable way to control and manipulate these correlated electronic states inside 2D TMD materials, with a high scalability, fidelity and quantum robustness. There are several sub-goals I am looking into:
- Large wafer-scale growth of monolayer TMD and their FET device architecture. This is the first obstacle one needs to overcome if one wants to make any real-world impact of these materials, that is to overcome the uncertainty and limited scalability of single-device transfer-based method of making 2D TMD devices. The method is to combine large scale, ulra-clean growth of monolayer TMD on silicon wafer, and transfer them automatically into wafer-scale circuit-level devices. Once this is achieved, with low thermal budget, in the applicable sense one is able to integrated the TMD transistors into BEOL segment of the modern silicon industry. Moreover, if a VLSI-level dual gate moire TMD architecture can be achieved, the following goal is not a dream anymore.
- Universal fault-tolerant quantum computation with non-abelian anyons in moire TMDs. It has been discovered that tMoTe2 system host fractional quantum anomalous Hall effect, which further leads to the excitation of anyons as a intrinsically strongly correlated electronic structures that cannot be explained through any single-particle fermionic/bosonic theories. It has also been proposed that the non-abelian species of these anyon excitations can form natural topological qubits for fault-tolerant quantum computation. Among the current quantum computation architectures, I found this routine the most physical, interesting and powerful way to utilize the natural gift of correlated electrons as qubit to programme them into a computer. Quantum computation is the mission of our generation of people to carry on. Therefore, I feel it aligns with not only my physical taste, but also philosophical spirit to achieve this goal.
- 2D high-Tc superconductors and their circuit-level applications. High-Tc superconductivity of electrons in solid states is the central theme of condensed matter research. Starting from earlier 1960s, the family of cuprates are discovered as the first and most important high-Tc superconductors, whose origins remain puzzling today. The main challenges of the study of cuprates is for such a bulk materials, the defects density is high and chemical doping efficiency is low. 2D van der Waals superconductors offer a new tunable platform with high electronic doping efficiency tunability to study those unconventional superconductivity.
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