The most profound question:  What is the universe?

The most embarrassing question: What is not the universe??


Jae-Weon Lee



Assistant Professor



School of Computational Science

KIAS (Korea Institute for Advanced Study)



207-43 Cheongnyangni 2-dong, Dongdaemun-gu,
Seoul 130-722, KOREA














Research Topics


1. Cosmology

My main research subjects in cosmology are DM, DE and inflation.

1) We suggest Dark energy is energy of cosmic Hawking radiation and related to entanglement

Articles about our model  in Newscientist , Sciencenews, and Korean news papers


Expansion of a cosmic horizon with a radius r induces information erasing at the horizon and it consumes energy due to the Landauer's principle. This energy can be dark energy. If  this information is represented by entanglement entropy this model becomes entanglement dark energy model which well fit observations. Inflation can solve easily the cosmic coincidence problem with this model. Finally we concluded   that Hawking radiation from cosmic event horizon could be DE!.


2) We suggest Dark matter is in BEC or coherent scalar field (Boson star, fuzzy, SFDM)!


 In 1992 Prof. Sin suggested galactic dark matter halos are in BEC. In the same year, I generalized this model to the first scalar field dark matter (SFDM)  (boson star) model. These models are free from the cusp problem and satellite galaxies problem threatening the standard LambdaCDM model. Recently it was also shown that the rotation curves of dwarf galaxies fit well with predictions of these models! These two models are now known as fuzzy CDM, repulsive DM  or SFDM.

BEC DM acts as cold dark matter at the super-galactic scale while it gives a finite length scale

suppressing sub-galactic structures    à ideal alternative to standard CDM

This model explains

l  Cusp, Missing satellite, Angular momentum Catastrophe

l  Rotation curves & ripples in them

l  Bullet cluster collision mystery

l  Size evolution of massive galaxy

l  Minimum mass for galaxy

l  Large scale structure formation

l  And morec

More and more observational evidences support this idea!


 3) Black hole and quantum information


 We are studying relation between black hole (BH) and quantum information erasing. We apply the same idea of information dark energy to BH. When matter enter BH horizon its information can be erased and this consumes energy due to the Landauer's principle. This energy can be black hole mass.  We are studying also  the black hole information paradox with this idea.



2. Entanglement and Qauntum Cryptography (QKD) 

 1) Entanglement


My main research subject is entanglement in quantum fields, cosmology and computational complexity. I also interested in relativistic entanglement and foundations of quantum physics. Phys.Rev. A74 (2006) 044304


2) Korean quantum cryptography system by ETRI team



ETRI, KIAS and Korea University  team developed Korean QKD system in 2005 in a project of korean government. I played a role of theoretian in this project and studied privacy amplification and error correction of this system.