Abstract: Recently, there is growing interest in the idea that quantum entanglement is the source of gravity and spacetime itself. This implies the deep connection between quantum information and fundamentals of physics.
I review how dark energy, the Einstein gravity and spacetime emerge from entanglement of quantum fields.

Abstract: When repetitive structures are overlaid against each other, a new superimposed moir? pattern emerges and is observed in various macroscopic phenomena. Likewise, in case the lattice periods do not coincide between atomically thin layers, the moir? interference between the lattices makes a new class of superlattices where the influence of the exceptionally long-period interlayer interaction is crucial to determine its electronic structures1,2.
In this talk, we will first discuss the impact of two-dimensional moir? superlattice formation for graphene systems and for hybrid layered-structures, and show that their electronic and optical properties are significantly altered if compared with those of the pristine graphene1,3. Then, we will show that the moir? superlattice affords a unique opportunity to study the fundamental problem on the motions of electrons under the simultaneous influence of a periodic potential and a magnetic field in the normally inaccessible regime of quantum Hall effect, aka Hofstadter’s butterfly4. The non-monotonic behavior of quantized Hall conductivity5 and the nesting of optical selection rule in the fractal energy spectrum will be discussed6. And we will show that aperiodic multi-walled nanotubes can be classified into one-dimensional moir? crystals with distinct electronic structures. Even the combination of single-walled nanotubes with almost the same physical properties can end up with very different superlattices depending on the interlayer moiré interference.
References
1. P. Moon and M. Koshino, Phys. Rev. B 87, 205404 (2013).
2. M. Koshino, P. Moon, and Y.-W. Son, Phys. Rev. B 91, 035405 (2015).
3. P. Moon and M. Koshino, Phys. Rev. B 90, 155406 (2014).
4. P. Moon and M. Koshino, Phys. Rev. B 85, 195458 (2012).
5. C. R. Dean et al., Nature 497, 598 (2013); B. Hunt et al., Science 340, 1427 (2013).
6. P. Moon and M. Koshino, Phys. Rev. B 88, 241412(R) (2013).

Abstract: Roughly speaking, ergodic Ramsey theory deals with Ramsey type results via ergodic methods. Ramsey theory, a branch of combinatorics, is concerned with the phenomena of the preservation of highly organized structures under finite partitions. Ergodic theory is the study of long term behavior of dynamical systems and one of the important themes in ergodic theory is the phenomena of recurrence. In this talk we will discuss some results to exhibit intrinsic connections between these two distinct areas.

Abstract: The goal of physics is to provide a mathematical model for everything in the universe.
The phenomena of life is the subject of particular interest in these days, and the subdiscipline of physics that studies biological system is called the biophysics.
In this talk, I review my recent research interests in thisdirection.